Handbook for Curing the Common cold - George A. Eby




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Handbook for Curing the Common Cold
The Zinc Lozenge Story








George A. Eby









Copyright Page

Published by:
Publications Division
George Eby Research
Austin, Texas U.S.A.

Copyright (c) 1994 by George A. Eby

All rights reserved. With the exception of factual figures presented, no part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise without prior written permission from the author. Absolutely no unauthorized reproduction is allowed under penalty of law.

As long as the source is properly credited, the publisher gives permission to all to reproduce figures within this publication, as most technical figures are equated with unadorned facts and they -- and most other technical figures and support data regardless of source -- are not copyrightable under existing United States case law.

Copyright (c) 1994 by Charles A. Pasternak - Foreword
Copyright (c) 1994 by David A. J. Tyrrell - Foreword
Copyright (c) 1994 by Widad Al-Nakib - Foreword

Copyrights for articles in Appendix:

Copyright (c) 1993 American Society for Microbiology, "Reduction in Duration of Common Colds by Zinc Gluconate Lozenges in a Double-Blind Study." (used with permission)

Copyright (c) 1993 British Society for Antimicrobial Chemotherapy, "Prophylaxis and Treatment of Rhinovirus Colds with Zinc Gluconate Lozenges." (used with permission)

Library of Congress Catalog Card Number: 93-090841

ISBN: 0-9638967-0-9

Printed in Austin, Texas, United States of America.
First edition, first printing: February 14, 1994,

Internet publication: December 3, 2002



















Dedicated to my daugther,

Karen Lynn Eby

and

serendipity
























Table of Contents

  • Chapter 1. Introduction - page 1
  • Magnitude of Health Problem
  • Etiologic Agents
  • Seasonal Variation in Etiologic Agents
  • New Evidence for Rhinoviruses as Principal Cause of Colds
  • Immune Response of the Nose
  • Overview of Common Cold Treatments
  • Introduction of Zinc Gluconate Lozenges
  • Stability Constants
  • Calculating Availability of Zn2+ Ions
  • Consideration of Body Acid-Base Balance
  • Chapter 1. References

  • Chapter 2. In Vitro Effects Of Zn2+ Ions - page 9
  • Antiviral Effects of Zinc Ions
  • Antibacterial and Antifungal Activity
  • Astringency
  • Non-Specific Membrane Protection
  • Cytolysin
  • Complement
  • Mast Cells
  • Histamine or Kinins in Colds?
  • T-cell Lymphocytes
  • Interferon Induction
  • Anti-Inflammatory Action
  • Zinc, Stress, and Common Colds
  • Overview of Effects of Zn2+ Ions in Common Cold Therapy
  • Chapter 2. References

  • Chapter 3. Zinc Lozenge Method of Treating Colds - page 25
  • Nasal Administration and Systemic Absorption
  • Oral Cavity Absorption
  • Mouth-Nose Electric Circuit
  • Fick's First Law
  • Ionic Diffusion
  • Zinc Ion Availability (ZIA) Values
  • Mathematics Of Common Cold Duration
  • Chapter 3. References

  • Chapter 4. Effects of Zinc Lozenges on Duration of Common Colds page - 33

  • Chapter 5. Central Finding of Linear Relation between ZIA and Efficacy - page 63
  • ZIA Factors
  • Comparative ZIA Values
  • Projection of Negative ZIA Values
  • Taste Scale and ZIA
  • Concession to Taste Through Use of a Double Loading Dose
  • Zn2+ Ions and Zinc Compound Molar Concentration with ZIA Values
  • Chapter 5. References

  • Chapter 6. Effects of Flavor-Masking on Efficacy - page 71
  • Strong Chelation of Zinc
  • Various Non-Chelating Flavor Masks
  • Anethole as Flavor Mask
  • Low ZIA Value for 5-Gram Zinc Gluconate Lozenge
  • Search for Efficacy and Pleasant Taste
  • Chapter 6. References

  • Chapter 7. Zinc Acetate Lozenges, Successor to Zinc Gluconate Lozenges - page 77
  • Zinc Acetate as Source of Zn2+Ions
  • Flavor Stability
  • Other Formulations
  • Eliminating Astringency from Zinc Lozenges
  • Chapter 7. References

  • Chapter 8. Zinc Biochemistry - page 88
  • Zinc in Genetics
  • General Zinc Biochemistry
  • Zinc, HIV, and AIDS
  • GRAS Status Assessment
  • Recent Human Safety and Toxicologic Data
  • Lack of Toxicity in Common Cold Studies
  • Possible Adverse Effect in Pregnancy
  • Industrial Safety and Material Safety Data Sheet for Zinc Acetate
  • Concluding Comments on Toxicity
  • Chapter 8. References

  • Chapter 9. Conclusions and Recommendations - page 97
  • Recommended Standard Zinc Acetate Lozenge Formulation
  • Recommended Advanced Design Zinc Acetate Lozenge Formulation
  • Changes in Formulation Allowable
  • Minimum Effective Dose
  • Manufacturing Variables Affecting ZIA
  • Importance of Placebo Matching
  • Differences in Lozenge Taste Perception in Well and Ill Volunteers
  • Placebo Lozenge Formula Considerations
  • Recommended Placebo Lozenge Formula
  • Recommended Clinical Trial Protocols
  • Improving Clinical Result
  • Expected Clinical Results from Advanced Design Lozenges
  • Full Circle
  • Expected Side Effects and Contraindications
  • Use of Zinc Acetate Lozenges to Treat Upper Respiratory Allergy
  • Use of Zinc Acetate Lozenges to Treat Mononucleosis
  • Concluding Remarks
  • Chapter 9. References








  • List of Figures

  • Figure 1. Distribution of zinc ionic species in the Zn2+ and gluconic acid system
  • Figure 2. Effect of different half-lives on percent of patients with symptoms on various days, showing weighted average durations
  • Figure 3. Duration of common colds in ZIA 100 zinc gluconate- and placebo-treated groups
  • Figure 4. Average total severity of colds in ZIA 100 zinc gluconate- and placebo-treated groups
  • Figure 5. Daily clinical score of ZIA 43.9 zinc gluconate- and placebo-treated groups
  • Figure 6. Daily nasal secretion weights in grams for ZIA 44 zinc gluconate- and placebo- treated groups
  • Figure 7. Duration of common colds using bitter ZIA 25 zinc gluconate and placebo
  • Figure 8. Effect of very low dosage ZIA 13.4 zinc gluconate and placebo
  • Figure 9. Effect of ZIA 0 zinc orotate and placebo lozenges and zinc gluconate nasal spray
  • Figure 10. Estimated effect of ZIA 0 zinc aspartate and placebo lozenges
  • Figure 11. Mole fraction Zn2+ species versus pH for solution with Zn2+ and excess citric acid (H3L)
  • Figure 12. Mole fraction for equimolar zinc and citric acid at 10 mMol
  • Figure 13. Estimated effect of ZIA -12.5 zinc gluconate-citrate and placebo lozenges
  • Figure 14. Estimated effect of ZIA -54 zinc acetate- tartarate-carbonate lozenges and placebo
  • Figure 15. Letter from R. J. E. Williams showing procedure and method for producing effervescence in zinc acetate lozenges
  • Figure 16. Estimated effect of zinc gluconate-glycine and placebo on duration of colds
  • Figure 17. Effect of pretreatment cold duration for zinc gluconate-glycine treated sub-groups
  • Figure 18. Concentration of Zn2+, and various zinc glycinate and zinc hydroxide species in the zinc gluconate-glycinate system
  • Figure 19. Relationship of zinc ion availability (ZIA) values and reduction in duration of common colds
  • Figure 20. Concentration of Zn2+ ion in the zinc and acetate system by pH
  • Figure 21. Effect of compressive force upon dissolution times
  • Figure 22. Effect of compressive force upon ZIA values
  • Figure 23. Effect of zinc content on ZIA and Zn2+ mMol concentration
  • Figure 24. Relationship of lozenge zinc content to saliva production.
  • Figure 25. Relationship of lozenge zinc content to lozenge dissolution rate
  • Figure 26. Effect of force applied to lozenge thickness
  • Figure 27. Expected effect of ZIA 100 and ZIA 400 lozenges







    List of Tables

  • Table 1. Characteristics of 80 subjects
  • Table 2. Number of patients reporting common cold symptoms at various times
  • Table 3. Average severity of 10 common cold symptoms at various times
  • Table 4. Side effects and complaints
  • Table 5. 11.5-mg zinc lozenge formulation tested by McNeil Consumer Products Company
  • Table 6. Examples of citric acid - sodium bicarbonate in effervescent formulations from Mohrle
  • Table 7. ZIA factors (zinc, fraction Zn2+, dissolution times, doses per day and saliva generated)
  • Table 8. Study lozenges, ZIA values, electronic charge, and reduction in duration of colds.
  • Table 9. Lozenge taste, salivary pH, near aftertaste and overnight aftertaste
  • Table 10. Zinc2+ ion and zinc compound salivary molar concentration compared with ZIA values
  • Table 11. Characteristics for preliminary 23-mg zinc (zinc acetate) 5-gram lozenges having different directly compressible bases
  • Table 12. Medicinal ingredients for incorporation into common cold lozenge
  • Table 13. Advanced design 15 mg zinc (zinc acetate) lozenge characteristics (3.5 and 5.0 gram)
  • Table 14. Average zinc content, ZIA, Zn2+ ion concentration and saliva production from zinc acetate lozenges
  • Table 15. Source and cost of zinc acetate lozenge ingredients
  • Table 16. Possible daily intake of zinc in milligrams per kilogram of body weight











    Foreward by Charles A. Pasternak, PhD, MD

    Today, zinc supplements are found on the health-food shelves of pharmacies and drug stores, alongside ginseng, yeast extract, and oil of wintergreen. But let us not forget that today's alternative or homeopathic medicine -- complementary is probably a better word -- is tomorrow's orthodox medicine. There are plenty of examples to illustrate this point: from the use of digitalis to prevent heart attack or quinine to prevent malaria, to the technique of vaccination to prevent infectious disease. The latter is a particularly striking example. Three centuries ago the practice of variolation (inhaling the pus from a small-pox victim to protect oneself against the onset of this disfiguring disease) was not so much an old wives' tale as a young mistress's tale: having been used for centuries earlier by the Chinese, it was prescribed for the Circassian maidens who inhabited the sultan's seraglio in the Ottoman Empire to protect their luscious skins. Today, following on from the success story of the small-pox vaccine, billions of dollars are being spent by the most respected research establishments of the world to develop vaccines against malaria, influenza, HIV, and a host of other infectious agents. If we had a vaccine against rhinoviruses, we might not need to fight the common cold with Zn2+ ions from zinc lozenges.

    The trouble with zinc is that, like vitamin C, it is present in most of our diets in quantities sufficient to prevent major deficiency disease (rare enough, anyway, in the case of zinc). Why should we take more? The answer lies in the way in which vitamins and other essential nutrients such as iron, copper, zinc, or iodine work: with the possible exception of iodine, whose function seems to be confined to the thyroid gland, most other vitamins and nutrients play a role in practically every tissue of the body. For example, while the dietary intake of vitamin C or zinc by healthy people of the Western world may be sufficient to prevent scurvy or the skin disease of Acrodermatitis enteropathica, respectively, this does not mean that a little bit extra may not be beneficial in fighting a number of different infectious diseases. For not only do vitamin C and zinc function in many different tissues, but the natures of those functions are manifold. Zinc, for example, is required for dozens of quite different molecular interactions within cells: it is easy to envisage that at a particular dietary intake most of these work normally, but one or two are below par; this would place the individual at risk for the onset of disease. Moreover, the imposition of a particular stress such as a viral infection places additional demands on certain cells within the body, and no one should be surprised that a higher concentration than normal of a critical nutrient such as zinc turns out to be beneficial.

    George Eby is a courageous man. He is neither scientist nor physician, yet he has battled with the medical establishment and pharmaceutical companies for a decade to persuade them to take seriously his proposal regarding throat lozenges releasing Zn2+ ions as an effective treatment for common colds. There is room in all walks of life for astute and intelligent men like George Eby: the challenge from inquiring and critical laymen is often immensely beneficial to scientists and physicians set in their ways. And who in the United States can doubt the contributions made by their most eminent layman -- President Thomas Jefferson? While George Eby's suggestion 15 years ago that his hospitalized leukemic daughter be given additional nutrients that included zinc may have not been as dramatic as the decision 250 years ago of Lady Mary Worley Montague -- wife of the British Envoy in Constantinople -- to administer a small dose of live small pox to her son to protect him against subsequent exposure, George Eby may nevertheless have stumbled onto more than one novel form of therapy using zinc. Read what follows and judge for yourself.


    Charles A. Pasternak, Ph.D., D.Sc., Hon M.D.
    Professor of Biochemistry
    University of London at
    St George's Hospital Medical School
    London (UK)
    and
    Director of the Oxford International
    Biomedical Centre







    Foreword by David AJ Tyrrell, MD, Director

    Some years ago George Eby noted that using zinc gluconate lozenges apparently benefited his daughter's colds, so he organized a clinical trial to test the idea. The results showed that such treatment improved the outcome. Although the trial did have some faults, we conducted a further test of his formulation in volunteers given experimental colds at the Common Cold Unit at Salisbury. The results of the test seemed to show benefit if the lozenges were given before or during the cold, yet similar studies at the excellent unit at the University of Virginia failed to confirm our findings.

    Mr. Eby has taken expert advice and investigated the possibility that it isn't merely the presence of zinc in the lozenge which matters, but the amount and duration of the Zn2+ ions released that determines whether there is an effect or not. He has combined his own studies of the characteristics of the formulations used with the published results of trials in a type of meta-analysis. It is not possible to present the amount of benefit in formally the same terms, but the results do support his case that the differences might be due to the release characteristics of the Zn2+ ions.

    Of course this doesn't settle the problem. It has been suggested that our trials failed to control adequately for the volunteers guessing whether they had active or placebo lozenges, and so produced a spurious positive result. There is also the problem that there is no evidence that Zn2+ ions actually reach the infected mucous membranes in the nose; however, in a sense that does not matter as there are many examples of active treatments being discovered when there was no evidence of how they worked.

    It is therefore worthwhile keeping the debate open in spite of the negative results in some trials and other much less plausible claims for benefits from zinc. This book helps in that debate by bringing together summaries of the biology of zinc, the results of the trials in common colds and the results of the analyses of the formulations used. The texts of original papers are also there to help the careful reader.

    I welcome this book. The best result of its publication would be at least one vigorous trial using zinc lozenges formulated with precisely the characteristics of those used and recommended by Mr. Eby, and with vigorous monitoring of the double-blind precautions and the clinical course of the patients.

    David A. J. Tyrrell, M.D.,
    retired Director Common Cold Unit
    British Medical Research Council,
    Salisbury (UK)

    and currently with the:
    British Medical Research Council
    AIDS Directed Programme Public Health Laboratory Service
    Centre for Applied Microbiology and Research
    Porton Down, Salisbury, UK






    Foreword by Widad Al-Nakib, MD


    In 1994, there continues to be a debate as to the efficacy of zinc in the prevention and/or treatment of the common cold. The initial studies conducted by Eby et al (1984) did suggest some efficacy although the trials were not perhaps as vigorously controlled as they should have been. We conducted double blind placebo-controlled studies at the MRC Common Cold Unit in Salisbury and found some benefit if the lozenges were given just before or after the onset of colds. One of the main criticisms of our trials was that there was not a sufficient number of volunteers in the second phase of the study which was the treatment with zinc lozenges. Studies in the USA and Australia however, failed to confirm these findings. This book attempts to review the role of zinc lozenges in the prevention and treatment of the common cold and summarizes the biology of zinc. I, like David Tyrrell, therefore welcome this book and hope that it would continue to debate the subject further with the hope that it may encourage further controlled trials.



    Widad Al-Nakib, MA FRCPath PhD
    Principal Investigator, Common cold Unit
    British Medical Research Council CCU
    currently at Advanced Pathology Services
    London UK












    Preface

    In an effort to provide a unifying hypothesis, this handbook analyzes all reports of zinc lozenge for common cold research reported since publication of my 1984 article in Antimicrobial Agents and Chemotherapy which documented a way of reducing the average duration of common colds by seven days using zinc gluconate lozenges. Common colds are mostly caused by rhinoviruses, and zinc gluconate is a good source of Zn2+ ions which are antirhinoviral.

    The story has been told around the world of how in 1979 my leukemic 3-year old daughter, Karen, started a revolution. She had refused to swallow her 50-mg zinc supplement because she had a severe common cold. Instead, she allowed the zinc gluconate tablet to dissolve slowly in her mouth during an afternoon nap, resulting in the termination of her cold within several hours -- without further treatment or relapse. After this serendipitous discovery, I found similar results in other family members, friends, and co-workers.

    Swallowed tablets, nasal ointments, nasal sprays, and nose drops were also tested. Nose drops were expected to work better than lozenges; however, no reduction in duration of common colds was observed. The dichotomy was difficult to understand, as colds are an infection of the nose, not the mouth. In retrospect, these findings are consistent with published literature dating from 1901 on zinc treatment of nasal catarrh via the nasal route as a short-lived nasal decongestant.

    Why? A biologically closed electric circuit (BCEC) between the mouth and nose controls local movement of metallic ions. Of the many BCECs described in 1984 by Björn E. W. Nordenström, the mouth-nose BCEC is the most readily observable.

    Over a two-year experimental period from 1979 to 1981, I formalized what I thought to be the best protocol for using zinc gluconate lozenges. William W. Halcomb (a general practice physician and allergist now in Mesa, Arizona), Donald R. Davis (a nutrition scientist who worked for National Academy of Science member Roger J. Williams [deceased] at the Clayton Biochemical Institute Foundation at the University of Texas at Austin), and I conducted the original double-blind study using slow-dissolving zinc gluconate tablets -- as lozenges -- in the fall of 1981 to treat wild common colds.

    The results showed the expected efficacy. Zinc gluconate lozenges reduced the average duration of common colds by seven days, with exceptionally strong statistical significance from the first few hours, again without relapse of colds. Our article caused others to attempt to replicate our findings.

    In 1984, the Medical-Scientific Director of RBS Pharma-Milan (now part of Rôhne-Poulenc Pharma, Italia, S. P. A.), Rinaldo Pellegrini sought my team's advice on how to compound zinc gluconate lozenges. By that time, my team had completed a no-effect zinc orotate (non-ionizable) lozenge for common colds study. On the basis of the conflicting zinc gluconate and zinc orotate results, we recommended avoidance of zinc chelators in lozenges. The pleasant-tasting, fructose-based RBS Pharma lozenges were tested on experimental colds by David A. J. Tyrrell and co-workers at the Great Britain Medical Research Council (MRC) Common Cold Unit. Analysis of the data from the MRC study showed nasal secretions essentially returned to normal in the zinc-treated group by day 4, while colds in the placebo-treated group continued. Analysis of mean clinical scores showed colds were essentially absent in six days with zinc treatment. Compared to the historic average of 10.8 days for untreated colds, a reduction of 4.8 days in common cold duration occurred. For the first time, an internationally recognized common cold research group verified a clinical treatment to shorten common cold symptoms. The positive results were discomfiting to the MRC scientists, because the operative mechanism remained elusive.

    The issue became confounded when other studies came up with different findings from the Texas and MRC studies. Some zinc gluconate lozenges had objectionable taste and long-lasting aftertaste, seriously impairing patient compliance. Zinc gluconate developed a reputation for being bitter, and lozenges needed flavor-masking. Actually, bitterness results only when zinc gluconate is combined with dextrose. Zinc gluconate in fructose -- as in the MRC lozenges -- tastes pleasant when flavored and has a mild aftertaste. The wide disagreement between studies caused researchers to assume the positive findings to be faulty. In 1988, letters to the editor of Antimicrobial Agents and Chemotherapy suggested differences in stability constants as being responsible for failures. The letters produced both insightful, and misleading information.

    In apparent defense of citric acid flavor-masked zinc gluconate lozenge work, one letter asserted zinc gluconate-citrate lozenges produced a salivary pH of 2.3 (stomach acid pH), contending one hundred percent of the zinc was released as Zn2+ ions.

    Realizing the improbability of a salivary 2.3 pH from use of the zinc gluconate-citrate lozenges and the improbability of availability of Zn2+ ions at physiologic pH, Guy Berthon, Director of Research at INSERM Unit 305 in Toulouse, France, entered the fray. One responsibility of INSERM Unit 305 is to determine the bioavailability of drugs at physiological pH 7.4, the only relevant pH for antivirals and many other chemotherapeutic agents. Determination of bioavailability is a complex and difficult effort involving solution chemistry. After a close collaboration between Guy Berthon and myself from 1988 to 1993, a report was produced thoroughly examining bioavailability of Zn2+ ions from the conflicting zinc lozenge articles. The resulting report, -- The "Zinc Lozenge and Common Cold Story" -- is published separately by Marcel Dekker, Inc. in Handbook of Metal-Ligand Interactions in Biological Fluids, edited by Guy Berthon. We all owe Guy Berthon our gratitude. Had he not intervened, the work would have died, and I would have gone on to do something else, disillusioned and disappointed. Worse, an effective cure to the common cold would have been buried and probably never resurrected.

    Presentation of comprehensive solution chemistry data is part of the analysis of the various conflicting reports in this handbook. Guy Berthon's research demonstrated Zn2+ ions were available at physiologic pH from efficacious zinc gluconate lozenges. More importantly, he clearly and convincingly demonstrated Zn2+ ions were not available at physiologic pH from non-efficacious lozenges.

    Quantification of the amount of Zn2+ ions capable of penetrating oral mucous membranes through lozenge use relies upon Zn ion salivary concentration at pH 7.4 and time of contact, following Fick's laws of membrane diffusion. The zinc ion availability (ZIA) method of analysis discussed in Chapter 3 was developed in 1991 as an application of Fick's laws in a mouth-nose BCEC. ZIA values are determined by the availability of Zn2+ ions at pH 7.4 over time of absorption into oral mucosal membranes.

    Electrical charge of zinc species is important as Zn2+ ions are absorbed into oral tissues and follow a readily measurable mouth-nose BCEC. Neutral and negatively charged species are unaffected or repelled, respectively, and have no known biologic activity in treating colds.

    Comparing ZIA values of the zinc lozenges to the resultant changes in duration of colds yields a linear regression having a r (rho) value of 0.96, providing reconciliation of all previously divergent results and a sound statistical basis for a unifying hypothesis. For complete details, see Chapter 5 and examine Figure 19 entitled "Relationship of zinc ion availability (ZIA) values and reduction in duration of common colds." Lozenges having a positive ZIA released Zn2+ ions and were beneficial. Lozenges releasing no Zn2+ ions produced no results, and lozenges having negative ZIA values usually worsened colds.

    The ZIA versus cold duration relationship also demonstrates a method to predict outcome of future studies with assurance of results in clinical trials. Linearity in ZIA -- versus -- cold duration data is the heart of this handbook and forms the foundation for future research.

    Chapter 7 discusses zinc acetate lozenges as the successor to zinc gluconate for use in common cold treatment. Zinc acetate has essentially no taste in dextrose or fructose at efficacious ZIA values, and lozenges are flavor-stable when properly formulated. Zinc acetate lozenges release 100 percent of their zinc as Zn2+ ions at physiologic pH 7.4. Full ionization of zinc acetate is a significant improvement over zinc gluconate, as zinc gluconate releases only 30 percent Zn2+ ions possible at pH 7.4. Chapter 7 details findings relating ZIA-to-lozenge dissolution rates, compressive forces used in tablet manufacture, zinc dosage, lozenge weight, and many other variables. Chapter 7 also shows unexpected non-linearity in ZIA values as zinc acetate content is increased in lozenges.

    Without comprehensive solution chemistry and ZIA analyses, understanding differences between the zinc lozenges for common cold studies is impossible, as was found by Y. J. Potter and L. L. Hart, who surveyed literature describing use of zinc lozenges for common colds in the May 1993, issue of The Annals of Pharmacotherapy. Potter and Hart were given an impossible task, as they only had an idea of the complexity of the chemistry involved and did not have sufficient information (particularly critical unpublished lozenge design materials from manufacturers) to arrive at a correct conclusion.

    I believe governmental and pharmaceutical company officials, as well as the public, want an inexpensive and safe cure for common colds. Unfortunately, present society has been taught to equate common cold cures to the elusive fountains of youth sought centuries ago. Without this handbook, the literature seems to support that belief. I sincerely hope this handbook will stimulate medical researchers without vested interests in other common cold treatments to conduct clinical trials of ZIA 50 to 200 zinc acetate lozenges for common colds. Before the public can benefit, responsible public and private health officials must find the truth for themselves. Once the -- no cure for the common cold -- fable is universally revealed as false, perhaps governmental and pharmaceutical company officials will listen to my zinc lozenge story and the public will eventually benefit.

    Engraved in glistening white marble above the entrance to the University of Texas Main Building in Austin, Texas, which houses comprehensive medical, life science and pharmaceutical libraries, are the encouraging Biblical words: "Ye shall know the truth and the truth shall make you free."

    Perhaps the full truth about zinc lozenges and common colds established and preserved in this handbook will result in new, focused research and submission of a New Drug Application to the United States Food and Drug Administration for zinc acetate lozenges as cure for common colds. I have done all I can. I must place the future of zinc acetate lozenges as cure for common colds in the hands of others. Let's see what will be done. Assuming availability of appropriate finances and cooperation by common cold authorities and regulatory agencies, we can rightfully expect zinc acetate lozenges to win approval of a Food and Drug Administration New Drug Application, resulting in placement of zinc acetate lozenges as the cure for the common cold on the market within the next five years.


    signed George A. Eby






    Acknowledgments

    I am deeply indebted to a large number of scientists, medical researchers, and others to whom I can only say thank you. The following are acknowledged for specific participation:

    William W. Halcomb, now of Mesa, Arizona, conducted our 1984 clinical trial. Donald R. Davis and Mitchell E. Gidseg of Austin, Texas, helped in statistical analyses, writing the original 1984 text, and in many fruitful discussions.

    Bruce D. Korant, of Du Pont Central Research in Wilmington, Delaware, worked with Zn2+ ions and rhinoviruses and provided helpful insight.

    Rinaldo Pellegrini of Milan, Italy, Medical-Scientific Director of RBS Pharma-Milan, took the time to visit with us and listen to our warnings about metallic chelators and made the flavor-masked zinc gluconate lozenges successfully demonstrated by the British Medical Research Council Common Cold Unit in Salisbury, England (MRC).

    David A. J. Tyrrell and co-workers at the MRC Common Cold Unit had the courage to publish the clinical truth, even though they could not determine the operative mechanism, and for his kind foreword remarks.

    Guy Berthon, Director of Research at INSERM Unit 305 in Toulouse, France, went far out of his way to help, and single-handedly saved this line of research.

    Charles A. Pasternak, at St. George's Hospital Medical School, University of London, took the time to visit with me and explain how Zn2+ ions could stabilize cell plasma membranes and perhaps be the means by which zinc lozenges shorten colds. I am also grateful for his kind foreword.

    Bill Bannen of General Nutrition Products in Greenville, South Carolina, disclosed the McNeil formulation.

    Claude. B. Goswick of Texas A&M University, College Station, Texas, revealed the actual dosages used in the McNeil clinical trial.

    Jack M. Gwaltney Jr., of the University of Virginia at Charlottesville, Virginia, provided frank and helpful comments.

    R. Bruce Martin, University of Virginia at Charlottesville, Virginia, provided the formula and zinc-citric acid speciation data applicable to the Bristol Myers lozenges.

    R. J. E. Williams of Faulding LTD, Adelaide, South Australia, disclosed the formulation of the effervescent lozenges used by Robert M. Douglas. Robert M. Douglas, now at the Australian National University, National Centre for Epidemiology and Population Health in Canberra, has shown continued interest.

    M. L. McCutcheon of the University of Minnesota at Duluth, sent me an unpublished account of their failed zinc aspartate study (0 ZIA), which helped show that nothing happens if there are no zinc ions. Ira Hill of Research Directions in Locust, New Jersey, lent support and technical assistance.

    James W. McGinity, Salomon A. Stavchancsky, Roland A. Bodmeier, and others at the Drug Dynamics Institute, College of Pharmacy, University of Texas in Austin, gave much and varied assistance.

    Paul T. Zeltzer, now at the Developmental Biology Group at UCLA in Los Angeles started me on this line of inquiry while he was my daughter's oncologist. Richard M. Holt of Children's Hospital of Austin, Texas provided pediatric services and particpated in many helpful conversations. Michael Castleman, author, of San Francisco, popularized zinc lozenges for colds and has given me endless support.

    Allison E. Rowland of Texas A&M University, College Station, Texas, contributed much-needed editorial services.

    Most of all, I very much appreciate the support provided to me by my family. Thelma Lloyd Eby, my mother (deceased), who financed the beginning of this research; Patsy Ann Eby, my beloved wife who gives and gives and gives without end; Karen Lynn Eby, my beloved daughter, and the child who prompted the insight as well as the need for this line of inquiry at the tender age of three; and Colin Martin Eby, my beloved son, for his support and understanding.

    signed George A. Eby







    The Elephant - Adapted from a Famous Sufi Story

    Once there was a poor Persian village where all were blind. One day a strange new creature called an elephant appeared at the village wall. Since no one in the village had ever heard of an elephant, the three wisest of the blind villagers went out to discover what the new creature was like. They all felt the creature. The first blind sage felt the tail and said, "This creature cannot be an elephant, this is a rope!" The second blind sage felt the leg and said, "No, this is a tree!" The third blind sage felt the side and said, "No, you fools, this is a wall!"

    As the three sages argued amongst themselves, a lesser blind man, not knowing any better, mounted the elephant and rode away.

    Adapted from a Famous Sufi Story






    Chapter 1. Introduction

    Executive summary: Chapter 1 introduces (a) the multibillion dollar annual magnitude of the common cold problem, (b) new evidence showing rhinoviruses as the cause of 60 to 70 percent of colds, (c) the immune system's response to viruses as cause of common cold symptoms, (d) the universal failure of existing commercial treatments to reduce common cold duration, (e) the beneficial effects of zinc gluconate lozenges containing 23 mg zinc used every two hours while awake in reducing symptom severity and the average duration of common colds by seven days, (f) applicable scientific and mathematical concepts, and (g) the solution chemistry determination of a 30 percent hydrated Zn2+ ion release from zinc gluconate at physiologic pH 7.4.

    Handbook for Curing the Common Cold -- The Zinc Lozenge Story is provocatively titled. Some professionals may be inclined to reject this idea without reading past the first line. If so, consider that this handbook is a serious scientific writing on how to shorten the duration of common colds using zinc lozenges. This handbook shows zinc content alone is insufficient to determine efficacy; rather, the zinc compound used, the oral residence time, and other physical and chemical properties of lozenges determine lozenge efficacy.

    Most people do not believe a cure for the common cold will be developed until well into the 21st century. If the reader is discomforted by what he reads, it is because the handbook disputes the "no cure for the common cold" conception. Scientists and physicians sometimes become defensive, and even apoplectic, at the thought of a lowly inorganic created near the beginning of time in a distant supernova having such novel effects. For laymen to learn a simple, readily manufactured common cold cure is available now, and to find major pharmaceutical companies have ignored it can be a source of considerable irritation as well. Perhaps those companies have turned away only because they have not understood the complex issues and solution chemistry involved.

    A medical name for such rejection is the "tomato effect," according to Drs. James and Jean Goodwin writing in the Journal of the American Medical Association.(1) The Goodwins point out that many highly efficacious therapies, particularly very simple and inexpensive ones, are rejected if they are not completely understood. Often what gets lost in selecting a therapy are the only issues that really matter: Does it help? Is it toxic? How much does it cost?

    This handbook opens a bold new world with its comprehensive instruction for further exploration and maximization of understanding of the mechanisms of action, formula- dependent efficacy, safety, and low cost of zinc acetate lozenges. As with many other treatments, we may never be able to pinpoint the precise mechanism of action. With a billion or more colds per year in the United States alone, a cure is desperately needed -- whether it is simple or complex -- so long as it is effective, safe, and inexpensive. A simple solution for many colds is now available. It is not what classically trained scientists wanted, but it is available to those sufficiently secure in their own training to accept radical new concepts. The discovery of zinc lozenge for common colds must not, therefore, become another "tomato effect."

    Magnitude of Health Problem

    Acute respiratory illness accounts for over one-half of all acute disabling conditions annually according to national health survey data.(2) The common cold is the most common of identifiable acute respiratory disorders and accounts for about 20 percent of all conditions and ailments and about 40 percent of all respiratory conditions.(3) This includes 110 million disabling colds per year, causing about 300 million days of restricted activity, about 60 million lost days of school, and about 50 million lost days of work.(4) When considering minor, nondisabling respiratory illnesses, common colds represent a still higher proportion of respiratory diseases. They are estimated to occur at rates of two to five colds per person per year. About 5 percent of the population have a cold at any given time. Common cold symptoms usually last from a few days to two weeks, and one-half are over in a week. Over one billion common colds occur in the United States each year. Financial considerations of the common cold are staggering. About $5.5 billion per year are spent on colds in the United States. About $3 billion are spent on professional consultations with about $1.5 billion on remedies and about $1 billion on analgesics, much of that amount for treating common colds.(5) Many acute respiratory disorders affect human beings, but this handbook considers only the common cold, which is technically considered to be a viral, usually rhinoviral, infection of the superficial columnar cells of the nasal turbinate epithelium and perhaps the nasopharynx.

    Etiologic Agents

    Michael Castleman's book "Cold Cures"(5) accurately condenses much of what is currently known about the etiology of common colds. His book is cited in these sections because of its essential authenticity and readability and because Handbook for Curing the Common Cold is not about common colds per se, but their treatment with zinc lozenges. Individuals interested in the virology, immunology, and physiology of common colds should read the authoritative works of others.

    Common colds are induced by over 200 types of viruses, with over 113 types of human rhinoviruses causing the majority. Colds are also caused by corona viruses, influenza viruses, herpes simplex viruses, respiratory syncytial viruses, coxsackieviruses, parainfluenza viruses, adenoviruses, and echo viruses. Some colds are caused either by unknown agents or viruses causing systemic viraemia. Echo viruses, polio, measles, and some adenoviruses cause systemic viraemia as well as common cold symptoms. Most other viruses do not, and they remain in nasal and nasopharyngeal mucosa where they cause only common cold symptoms. Nasal drainage and nasal congestion are primary symptoms of common colds. Malaise, headache, fever, muscle pain, sore throat, scratchy throat, cough, and hoarseness are frequently occurring secondary symptoms.(5)

    Seasonal Variation in Etiological Agents

    Seasonal variations in cold-causing viruses have been noted with differences in host susceptibility.(5) Rhinoviruses cause colds year-round, and have been implicated in about 50 percent of all common colds occurring in the spring, summer, and fall, at least until recently. The large number of rhinoviruses (over 100 distinct rhinoviruses) and variants affecting children and adults make a vaccine essentially impossible. Frequency of rhinovirus infection falls off with age. Parainfluenza viruses have been implicated in 15 to 25 percent of fall, winter, and spring colds, affecting mostly infants and children. This family of four viruses causes severe colds in infants with significant potential for complications, but only mild colds in adults. Various strains of influenza A and B are implicated in 10 to 20 percent of cold-like illnesses in late fall, winter, and early spring. Influenza causes particularly severe symptoms as well as many more cold-like illnesses during periodic worldwide epidemics. Coronaviruses, a family of 13 viruses having a distinctive crowned appearance under the electron microscope, cause 10 to 20 percent of upper respiratory infections and are most active in winter and spring. Respiratory syncytial viruses (RSV) have been implicated in about 10 percent of colds. These viruses are usually found in fall, winter, and spring colds. They cause mild colds in adults, but are the leading cause of pneumonia in infants. Ribavirin has been shown effective in RSV pneumonia. Three out of more than 40 adenoviruses cause about 5 percent of winter colds. Military recruits are at the greatest risk. Adenoviruses are most active in fall and winter. Strains of echoviruses and coxsackieviruses, part of the enterovirus group, cause 5 to 10 percent of colds. These enteroviruses are active from April through December with peak activity in summer and fall. They affect mostly infants, children, and military recruits with typical cold symptoms and possibly diarrhea. Other viruses cause up to 25 percent of colds year-round. Herpes simplex viruses can cause colds of long duration. Rhinoviruses cause colds year around, but they are most active from April through October, not during the height of the annual cold and flu season.(5)

    New Evidence for Rhinoviruses as Principal Cause of Colds

    British researchers using new techniques have very recently suggested rhinoviruses account for 60 to 70 percent of all common colds, not 30 to 50 percent as previously reported. Sebastian Johnston, of the Department of Microbiology at the University of Southampton in England, recently used polymerase chain reaction techniques to develop ultrasensitive tests to better identify cold viruses in asthmatic children. In 108 children, age 9 to 11 years with asthma, 290 respiratory complaints (common colds and chest infections) were examined with the new research methods. Seventy-eight percent of all complaints were virally related, and of them 60 to 70 percent were caused by rhinoviruses.(6)

    Immune Response of the Nose

    The nose is the body's first line of defense against airborne viruses.(5) The temperature and moisture of the inner nose tend to inhibit growth of some viruses. The nasal turbinates by their flap-like shape and copious blood supply assist in warming and moistening air. The interior of the nose is lined with goblet cells that excrete sticky mucus. The nasal interior also has cilia, tiny projecting hairs, that trap inhaled viruses, pollen, medication, and dust particles. Cilia move them down the throat, preventing contact with underlying cells in the nose and throat. The cells lining the respiratory tract also secrete immunoglobulin A (IgA) helping to prevent infections by combining with the surfaces of viruses and bacteria to change their shape into one not allowing attachment. Recently, intercellular adhesion molecule 1 (ICAM-1) has been identified as the molecule that attaches rhinoviruses to cells.(5)

    During a cold, viruses have managed to penetrate nasal mucus and invade nasal and perhaps nasopharyngeal tissues.(5) Viruses enter cells and within a few hours seize control of cell genetics and force cells to make thousands of copies of invading viruses. As cells become infected, they release chemicals initiating several responses from the body's immune system, including responses from immune cells of the nasal mucosa. Within an hour, prostaglandins are released producing inflammation and attracting infection-fighting white blood cells called neutrophils. These cells attempt to attack invading viruses without damaging infected cells. Neutrophil activity increases inflammation, and the infected area becomes swollen and red. Onset of a common cold is thus signaled with symptoms such as sore throat, itchy eyes, a headache, or a generalized ill feeling. Tissues and capillaries dilate, and plasma, more neutrophils, and other white blood cells flood the area. They cause increased mucus production, a raised temperature, a runny nose, sneezing, and coughing. Release of kinins, perforin, perhaps histamine, and other mast cell vasoactive ingredients increase capillary permeability and cause increased mucus production by goblet cells.(5)

    If raised nasal temperature and neutrophil engulfment are insufficient to stop viral invasion, monocytes and lymphocytes pass though capillary walls and assist.(5) In the presence of inflammation and other signs of infection, monocytes transform themselves into macrophages eating as many as 100 viruses each. These cells release interleukin- 1 causing the body's temperature to rise and activate lymphocytes. Release of interleukin-1 to reset temperature results in chills, which often precede a fever.

    B- and T-cell lymphocytes are the main warriors in defense of the nose. B-cells produce immunoglobulins. These antibodies plug cold-virus receptor sites and prevent viruses from sticking to nasal and nasopharyngeal cells. Some of these cells become memory cells helping to prevent recurrence of infection. T-cell lymphocytes when summoned to the site of infection turn into "killer cells" that release cytolysin (perforin) which opens pores in cells. Killer cells attack and kill virus-infected cells. Other "helper/inducer" T-cells stimulate B-cells to produce additional antibody. Some T-cells become "suppressor" T-cells terminating antibody production and killer-cell activities after viruses have been controlled. T-cells also release several other infection- managing chemicals, including macrophage activation factor, macrophage inhibition factor, interleukin-1 and -2, and interferon. Interferon prevents cell death caused by viruses and prevents viral replication. Complement proteins lyse cells and coat virus particles making it easier for macrophages to recognize and digest them. Complement aids killer cells in identifying infected cells, which must be destroyed. Common cold symptoms are not produced by viruses, but by the immune system's many, perhaps over reactive, responses to viral infection.(5)

    Overview of Common Cold Treatments

    Throughout recorded history, common colds have been refractory to attempts to shorten their duration. Whether treated or not, the half-life of common colds remained about 7 days with an average duration of about 10 to 11 days. Treatment and advice include: Pliny the Younger's first century treatment of "kissing the hairy muzzle of a mouse," avoiding dampness and exposure to cold temperatures, avoiding sneezes of persons with colds, avoiding shaking hands, eating chicken soup, taking various herbs, mentholated lozenges, eucalyptol lozenges, horehound lozenges, antihistamines, nasal decongestants, analgesics, cough syrups, antitussives, inhaling warm moist air, taking megadoses of Vitamin C, using interferon nasal sprays, "killer" tissues soaked in iodine, gargles, anticholinergics, humidifiers, negative air ions, meditation, acupuncture, electronic air filters, various antirhinoviral agents, antibiotics to prevent secondary infection, and, most recently, the use of zinc gluconate throat lozenges.

    Introduction of Zinc Gluconate Lozenges

    In 1984, zinc gluconate lozenges containing 23 mg of zinc used every two hours while awake (a lozenge about 9 times per day) were first reported by Eby and others at the University of Texas at Austin to shorten the duration of common colds by an average of 7 days when compared to placebo. Results of the study were carried by the Associated Press and became headlines in newspapers world-wide. This study showed the half-life of common colds treated with zinc to have been 2.7 days, compared to 7.5 days for placebo-treated patients. Statistical significance was high throughout the study (P = 0.0005 on the seventh day of treatment). Lozenges were unflavored, over-the- counter tablets having no soluble ingredients other than zinc gluconate. As a mildly objectionable chalky taste and aftertaste were reported by about one-half of the patients receiving zinc gluconate lozenges participating in the study, the statistics were also evaluated excluding patients expressing comments about taste or aftertaste. Results were found to remain the same, with high statistical significance.(7)

    This 1984 report stimulated follow-up research both in vitro and in vivo. The new in vivo work involved usage of chemically weaker and different lozenges, and controversy ensued. Orally absorbed hydrated Zn2+ ions transported mechanically and through preferential pathways in biologically closed electric circuits between the oral and nasal cavities are believed to be responsible for reduction in duration. Studies with positive findings demonstrate effects of lozenges releasing adequate Zn2+ ions while negative studies do not.

    The first stability constant of zinc gluconate is log K1=1.70, which means zinc gluconate is highly ionizable and allows ready release of Zn2+ ions into oral tissues for localized absorption. A maximum of 60 percent of zinc from zinc gluconate will be present in saliva as Zn2+ ions, but only a maximum of 30 percent will be present at pH 7.4, the pH of oral tissues, blood, and lymph. A percentage of Zn2+ ions is precipitated by salivary proteins and hydroxide, while active amounts are absorbed into the oral and oropharyngeal tissues. Having numerous pharmacologic properties, absorbed Zn2+ ions provide a nearly perfect common cold treatment.

    Follow-up in vivo studies were marred by efforts to eliminate objectionable taste in the zinc gluconate lozenges. No researcher attempted to replicate research using lozenges identical to lozenges used by the Eby group. Most efforts by pharmaceutical and nutritional supplement companies to prepare flavored, pleasant-tasting zinc gluconate lozenges failed. Those efforts resulted in lozenges that were much weaker in biologic activity. Also, those experimental lozenges usually tasted far more objectionable than the unflavored lozenges used in the original 1984 study. Because no other group attempted to replicate the original study with identical lozenges, it was not clear whether the original study was faulty or the "improved" lozenges were impotent because of Zn2+ ion unavailability or flavor- masking difficulties.

    Before the discovery of flavor-stable, pleasant-tasting zinc acetate lozenges, elimination of objectionable taste was by strong chelation by zinc binders such as citric acid, tartaric acid, sodium bicarbonate, glycine, aspartic acid, orotic acid, by addition of anethole flavor-mask, or by use of low-dosages of zinc.

    A good exception was the 1987 British Medical Research Council Common Cold Unit zinc lozenge for common cold study.(8) Using lozenges chemically identical to the original Eby group lozenges, the MRC Common Cold Unit study showed greater efficacy in shortening colds than any previous study ever conducted by the Common Cold Unit.

    Clinical failures of highly stable zinc complexes with excess chelator (essentially negatively charged zinc species), highly stable zinc complexes (essentially neutrally charged zinc complexes), and those lozenges containing very low zinc dosage have caused loss of credibility for all zinc lozenge compositions as effective common cold treatments, including those highly ionizable zinc compounds releasing large amounts of active Zn2+ ions. Without means to flavor-mask lozenges, it appeared Zn2+ ion might not become a useful tool in the fight against common colds. Creation of flavor-stable, pleasant- tasting zinc acetate lozenges as discussed in Chapter 7 herein, provides a new way to study the effects of Zn2+ ion in shortening common cold duration.

    Stability Constants

    To study zinc and the common cold, one must realize Zn2+ ions in amounts sufficient to shorten common colds are available only from a few highly soluble and highly ionizable zinc compounds. Some zinc compounds are soluble at oral tissue pH but do not release Zn2+ ions as they have been strongly sequestered by the ligand; other solubles release Zn2+ ions as they have been only weakly sequestered. For sequestration of metallic ions to occur, two general conditions must be met: (a) ligand must have proper stearic and electronic configuration in relation to metal ions being complexed, and (b) the surrounding milieu (pH, ionic strength, solubility, etc.) also must be conducive to complex formation. The capability of a ligand to release metal ions under these varying conditions is found using solution chemistry.

    Positively charged, aqueous solution zinc ions (Zn2+ ions) from very weakly complexed zinc compounds are the only form of zinc having anti-common cold properties including antiviral action, cell membrane protection, antihistaminic effect, and interferon-inducing properties. Zn2+ ions and several strongly chelated zinc compounds have T-cell lymphocyte and astringency activity. Anti-common cold zinc complexes and their relative antiviral strengths can be determined from the first stability constant (formation constant, equilibrium constant, or reciprocal of dissociation constant) of complexes of zinc and ligands. The theoretical importance of the availability of Zn2+ ions in treating common colds was demonstrated in 1989 by Merluzzi and co-workers at Boehringer Ingelheim Pharmaceuticals while working on the ICAM-1 project.(9,10) These scientists demonstrated the antirhinoviral effect of zinc to be directly related to the amount of Zn2+ ions available and completely unrelated to the total amount of zinc complex.

    Calculating Availability of Zn2+ Ions

    Stability constants, a measure of sequestering power of ligands (chelators) for metal- ions, are well defined and cataloged for zinc and other metals for many ligands.(11,12) Electrical charges of zinc-ligand complexes in Martell's six-volume Critical Stability Constants can be determined from the charges of metal ions and abbreviated ligand formulas given in tables in well-defined systems.(11) In these systems, the relative efficiency of metal-ion sequestrants can be compared by inspecting stability constants for metals. In general terms, the stability constant of a metal complex can be calculated as follows: K = [ML] / [M][L], where K is the stability constant and is usually expressed as a logarithm; M is the amount of metal ion such as Zn2+ ion, and L is the amount of a ligand such as gluconate or acetate.(11)

    According to a leading solution chemist, Guy Berthon of INSERM U-305 in Toulouse, France, the total concentration of metal CM can be computed with specialized computation programs. The basic equation CM = [M] + [ML] with [ML] = K [M] [L] becomes CM = [M] (1 + K [L]); hence [M] = CM / (1 + K [L]) shows that the concentration of M, Zn2+ ion in this case, depends on the stability constant of the complex and free concentration of the ligand which is dependent upon corresponding pK and pH values.

    For example, the above equation is used to compute the amount of Zn2+ ions positively charged zinc gluconate (ZnGl+), neutrally charged zinc gluconate hydroxide [ZnGl(OH)], and several other zinc hydroxide species using equilibrium-based computer computations. Figure 1 shows the various fractions of zinc species from zinc gluconate occurring at each pH in aqueous solution. About 30 percent is present as Zn2+ ion at the pH of oral tissue (pH 7.4) although 30 percent is a maximum value because some Zn2+ ions bind with salivary proteins and hydroxides forming precipitates in saliva. Zn2+ ions are absorbed into oral and oropharyngeal tissues. Only the orally absorbed Zn2+ ions have utility in shortening the duration of common colds.

    With increased first stability constant values in various other zinc compounds, more zinc is complexed by the ligand, leaving less metal in cation form at each pH.

    The first stability constant for zinc glycinate (log K1 = 4.8)(11,12,13) causes zinc as zinc glycinate to be more tightly bound and much less available at each pH over 3 than would zinc as zinc gluconate (log K1 = 1.70) or zinc chloride (log K1 = 0) or zinc acetate (log K1 = 1.03) because the latter compounds all have very have low stability constants.(11,12,14) Zinc reacts rapidly with ligands and instantly complexes in solution. In the compilation co-authored by Martell(11), the introductory remarks show only the most reliable data were used resulting in the omission of data for mixed ligands. Furia(12) provides a simplified table of first stability constants for metals and food ligands and provides a brief discussion of stability constants.

    Speciation of zinc in the gluconic acid system by pH

    Figure 1. Distribution of zinc ionic species in the Zn2+ and gluconic acid system. Curves were constructed from pK values shown after the reactions: Zn2+ + L_ <=> ZnL+ (1.62) and ZnL+ + OH_ <=> ZnL(OH)0 (8.14) at a concentration of 30 mMol zinc. The pK values are courtesy of Gerritt Bekendam, Akzo Chemicals BV Research Centre, Deventer, The Netherlands, 1989. The Zn2+ fraction over pH 6 is strongly affected by the second pK value. Precipitates of hydroxides of zinc result in supersaturated solutions. Computer- simulated distribution of zinc ionic species is courtesy of Guy Berthon, 1992.

    Stability constant values are valid only under well-defined laboratory conditions but appear to be reasonable starting points for use with zinc lozenges because conditions are similar. Body temperature is either slightly higher or identical, while salivary zinc concentrations are slightly lower than concentrations usually tested in laboratories. Published stability constants are vital for computation of amounts of Zn2+ ions and other zinc complexes at essential pH values.

    The presence in zinc lozenges of non-aqueous additives, such as sugars, sugar alcohols, food acids (strong chelators), bicarbonate (strong chelator), flavor oils, lake colors (strong chelators), tablet lubricants, tablet binders (possibly strong chelators), and other ingredients make analysis of net charge and concentration of Zn2+ ion much more uncertain, particularly where authors fail to list the amount of each ingredient.

    In two important cases (reviewed in Chapter 4 herein), metal-chelating additives reversed net charge, resulting in complete loss of Zn2+ ions at pH 7.4 and adverse clinical results.

    Consideration of Body Acid-Base Balance

    The only relevant pH in common cold therapy with zinc lozenges is the 7.35 to 7.4 range. All acids and other bases are quickly buffered to that pH range in blood, lymph, and tissue.(15,16) Acid-base balance in body tissues and fluids is carefully regulated in a state of good health and is always maintained within normal physiologic limits.

    The 7.4 pH of blood and extracellular fluid is close to the natural 6.8 pH of 20 mMol zinc acetate, suggesting good absorption potential as well as close approximation to laboratory pH conditions. The physiologic pH is about one log unit higher than the natural 6.2 pH of 20 mMol zinc gluconate.

    When using zinc lozenges, salivary proteins complex with and precipitate some Zn2+ ions at salivary pH, while some zinc is swallowed, and some is absorbed into oral and oropharyngeal tissues and is held at pH 7.4. Once absorbed, some Zn2+ ions are chelated by blood, lymph, and tissue while others remain in a hydrated ionic form. Whether or not a given amount of a zinc compound can 1) provide sufficient Zn2+ ions to be antirhinoviral in nasal tissue, 2) induce local interferon production, 3) provide local cell membrane stabilization, and 4) provide Zn2+ ions for the numerous other physiologic interactions at pH 7.4 is determined by the chemical stability of the zinc complex. Only absorbed Zn2+ ions available at pH 7.4 migrating from oral tissues into nasal and nasopharyngeal tissues are useful in shortening common colds. High Zn2+ ion concentrations in common cold lozenges at pH lower than 7.4 are irrelevant, misleading to the consumer, and useless in practice.

    Zinc compounds having very low stability constants such as zinc gluconate, zinc chloride, and zinc acetate release useful amounts of Zn2+ ions at pH 7.4, while zinc compounds with higher stability constants do not.

    For example, at pH 7.4, 100 percent of the zinc from zinc acetate (log K1 = 1.03) remains as hydrated Zn2+ ions,(17) while only 30 percent of the zinc from zinc gluconate remains as zinc ion (log K1 = 1.70).(11,12) Zn2+ ion availability from zinc sulfate, lactate, malate, maleate, tartarate, and succinate (log K1 = 1.8 to 2.8) ranges in effect from less than desirable to useless for treating colds. Essentially no Zn2+ ions occur at pH 7.4 from zinc citrate, oxide, glutamate, carbonate, glycinate, aspartate, orotate, amino acid chelates, EDTA, and other highly chelated zinc compounds (log K1 = 4.5 to 16.5),(11,12) rendering these compounds completely useless in treating colds. Examples of these effects are shown in detail in Chapter 4.

    Chapter 1. References

    1. Goodwin JS, Goodwin JM. The tomato effect: rejection of highly efficacious therapies. Journal of the American Medical Association. 1984;251:2387-2390.

    2. Acute Conditions, Incidence and Associated Disability, United States, July 1977-June 1978. National Health Survey publication (PHS) 79-1560. Washington DC: U.S. Department of Health, Education and Welfare; 1979:3.

    3. Fox JP, Hall CE. Viruses in families. Littleton, Mass: PSG Publishing Co; 1980.

    4. Murphy W. Coping with the Common Cold. Alexandria, Va:Time-Life Books. 1981.

    5. Castleman M. Cold Cures. New York:Fawcett Columbine; 1987.

    6. Johnston SL, Sanderson G, Pattemore PK, et al. Use of polymerase chain reaction for diagnosis of picornavirus infection in subjects with and without respiratory symptoms. Journal of Clinical Microbiology. 1993;31:111-117.

    7. Eby GA, Davis DR, Halcomb WW. Reduction in duration of common colds by zinc gluconate lozenges in a double blind study. Antimicrobial Agents and Chemotherapy. 1984;25: 20-24.

    8. Al-Nakib W, Higgins PG, Barrow I, et al. Prophylaxis and treatment of rhinovirus colds with zinc gluconate lozenges. Journal of Antimicrobial Chemotherapy. 1987;20: 893-901.

    9. Merluzzi VJ, Cipriano D, McNeil D, et al. Evaluation of zinc complexes on the replication of rhinovirus 2 in vitro. Research Communications in Chemical Pathology and Pharmacology. 1989;66: 425-440.

    10. Staunton DE, Merluzzi VJ, Rothlein R, et al. A cell adhesion molecule, ICAM-1, is the major surface receptor for rhinoviruses. Cell. 1989;56:849-853.

    11. Martell AE, Smith RM. Critical Stability Constants. New York:Plenum Press; 1991;1-6.

    12. Furia TE. Sequestrants in food. In Furia T.E. ed., CRC Handbook of Food Additives. 2nd ed. West Palm Beach, Fl:CRC Press; 1972:271-294.

    13. Alemdaroglu T, Berthon G. Trace metal requirements in total parenteral nutrition II. Potentiometric study of the metal-ion equilibria in the zinc-histidine, zinc-glycine,zinc-cysteine-histidine,zinc-glycine- histidine and zinc-glycine-cysteine systems under physiological conditions. Journal of Electroanalytical Chemistry and Interfacial Electrochemistry. 1981;128:49-62.

    14. Cannan RK, Kibrick A. Complex formation between carboxylic acids and divalent metal cations. Journal of the American Chemical Society. 1938; 60:2314-2320.

    15. Adler S, Fraley DS. Acid-base regulation: cellular and whole body. In: AI Arieff, RA DeFronzo, eds., Fluid, Electrolyte, and Acid-Base Disorders. New York:Churchhill Livingstone; 1985;1:221-257.

    16. Guyton AC. Regulation of acid-base balance. In: Textbook of Medical Physiology. New York:W. B. Saunders Company; 1986;37:438-451.

    17. Hacht B, Berthon G. Metal Ion-FTS nonapeptide interactions. A quantitative study of zinc(II)-non-apeptide complexes (thymulin) under physiological conditions and assessment of their biological significance. Inorganic Chimica Acta. 1987;136: 165-171.






    Chapter 2. - In Vitro Effects of Zn2+ ions

    Executive summary Chapter 2 describes in vitro beneficial effects of Zn2+ ions in (a) virology, with special attention to rhinoviruses, (b) bacteriology, (c) astringency, and Zn2+ ion's beneficial effects in stabilizing and protecting secretory cell membranes, (d) prevention of release of histamine, perforin, other common cold biochemicals, mucus, and serous fluids, (e) stimulation of primary T-cell lymphocyte immunity, (f) induction of interferon release from T-cell lymphocytes, and (g) reduction of inflammation in nasal tissues. In each case, the beneficial effects of Zn2+ ions from zinc lozenges are at nontoxic concentrations achievable in human throat and nasal tissues.

    Although the exact mechanism by which zinc shortens common colds may never be determined, the Zn2+ ion has multiple, biochemical effects in vitro, almost certainly acting synergistically in common cold therapy. According to Charles A. Pasternak of the St. George's Hospital Medical School at the University of London, hydrated Zn2+ ion at 6 to more than 60 times normal zinc serum concentration has multiple beneficial effects, increasing as extracellular Zn2+ ion concentration increases.(1)

    As discussed in detail below, the beneficial effects observed in treating colds with lozenges releasing Zn2+ ions are caused by 1) astringent drying action on all cell membranes including mucus-secreting goblet cells; 2) inhibition of rhinovirus replication above 0.05 mMol Zn2+ ion; 3) immediate protection and stabilization of cell membranes from all cytotoxic agents including cytolysin (perforin), with a strength equal to interferon; 4) induction of interferon-gamma within 24 hours; 5) immediate cell and capillary membrane pore closure and prevention of transcapillary serous leakage, a function which promotes long-distance closed-circuit transport of ions; and 6) immediate inhibition of release of histamine and other vasoactive biochemicals from mast cells and catabolism of histamine. Serum zinc concentration is 0.015 mMol.

    Elevated extracellular Zn2+ ion is beneficial and elevated intracellular zinc is cytotoxic, although recently some authors have suggested that slightly elevated extracellular zinc is cytotoxic. In some cells, rounding and refractile changes occur at about 0.1 mMol Zn2+ ion and at much lower concentrations for most lipophilic and strongly chelated zinc complexes. These observations were interpreted as cytotoxicity and suggested a low 1:2 or 1:4 antirhinoviral therapeutic index for zinc.

    Researchers highly familiar with the unique appearance of cell plasma membranes after the astringent action of Zn2+ ions, place the index at 10 to 100 times higher; as extracellular Zn2+ ion is a newly recognized host defense according to Pasternak.(1) Hydrated Zn2+ ions protect cell plasma membranes against damage induced by cytotoxic agents of environmental origin long enough for other defense mechanisms to be brought into play. Up to 1 mMol, Zn2+ ions protect cell plasma membranes in vitro.(1)

    No evidence of toxicity from lozenges releasing Zn2+ ions exists. The only adverse effect -- if it can be called that -- is mild, transitory oral irritation on occasion, even though lozenges used by Eby et al.(2) in 1984 produced initial salivary Zn2+ ion concentrations of 7.4 mMol. The highest recorded initial salivary Zn2+ ion concentration from zinc acetate lozenges is 21 mMol. Rather than being toxic to oral tissues, Zn2+ ions are associated with accelerated patient recovery. Oral irritation and strong taste sensation from strong lozenges are much less apparent in patients with colds than without colds, perhaps because of increased oral membrane permeability in patients with untreated colds.

    Antiviral Effects of Zinc Ions

    Positively charged Zn2+ ions from soluble, highly ionizable zinc compounds with very low stability constants were demonstrated to be highly effective antirhinoviral agents in vitro by Korant and others at Du Pont using HeLa cells (human epithelioid carcinoma of the cervix cells).(3) Many other metals were determined not to be antirhinoviral at nontoxic dosages. Korant and colleagues determined that Zn2+ ions inhibit cleavage of rhinovirus polypeptides. Addition of Zn2+ ions, at concentrations 0.1 mMol and above, at any time during rhinovirus replication immediately inhibited further formation of infective virions.(3) Antirhinoviral concentration is 6.67 times higher than normal zinc serum concentrations. Plaque-forming ability of rhinoviruses was reduced by 90 to 100 percent in eight of nine rhinoviruses tested.(3) Zinc ions rapidly inhibit virus production and lead to accumulation of rhinovirus precursor polypeptides cleaved predominantly to stable virus polypeptides upon removal of Zn2+ ion.(4) Zn2+ ions complex with rhinovirus coat proteins and alters them to prevent their function as substrates for proteases or as reactants in the assembly of virus particles.(4) Zn2+ ions were not shown to de-activate mature rhinoviruses.(3) The Du Pont team conducted an exhaustive five-year study of antiviral effects of Zn2+ ions on rhinoviruses and other picornaviruses.(3 - 10)

    A. S. Prasad, who is regarded as the father of human zinc nutrition research, suggested two ways by which Zn2+ ions block cleavage of rhinovirus proteins. One is by activation of one or more proteases. The other is by binding to and altering substrate so it cannot be cleaved.(11) The latter model is preferred because (a) Zn2+ ion almost immediately blocks virus production, suggesting one of the components of the virion is affected directly by Zn2+ ions; (b) Zn2+ ions interact directly with rhinovirus capsids; (c) sufficient amounts of purified virus will produce crystals, but amorphous precipitates form in the presence of a small amount of Zn2+; and (d) results of cleavage inhibition indicate sensitive proteolytic reactions invariably involve precursors containing capsid protein sequences.(11) No information on changes in intracellular zinc concentration from zinc was presented by the Du Pont team, and none is likely since elevated extracellular Zn2+ ions strongly inhibit cellular Zn2+ absorption.(1) Zn2+ ions render the cell plasma membrane non-permeable so the rhinoviruses cannot enter or exit, thus terminating viral replication.

    In 1989, Merluzzi and others showed antirhinoviral effects of zinc to be directly related to amount of Zn2+ available and unrelated to the total amount of zinc complex available.(12) As zinc was complexed with ligands of increasing binding strength, antirhinoviral activity proportionately fell. Maximum antirhinoviral effectiveness was with zinc chloride (K1 = 0.0). Minor increases in lipophilicity using crypate complexes drastically affected their toxicity to activity ratios, with increases in toxicity associated with increases in lipophilicity, suggesting lipophilic zinc complexes should not be used in throat lozenges to treat common colds.

    Cell rounding and refractile changes occur at about 0.1 mMol Zn2+ and at much lower concentrations for most lipophilic and strongly chelated zinc complexes.(12) These observations were interpreted as cytotoxicity by Merluzzi and co-workers.(12) The effect of 0.05 mMol Zn2+ from zinc chloride (one-half the concentration used by Korant and co-workers) was equal to human interferon-beta at its most effective concentrations of 100 to 1000 IU in its antirhinoviral activity and ability to protect infected cell monolayers.(12) No significant antirhinoviral activity for several zinc compounds was reported by Geist and associates (nor by Korant and others) at 0.03 mMol,(13) a Zn2+ ion concentration that does not produce cellular rounding and refractile changes. Antirhinoviral effects were similarly observed by Geist and co-workers at 0.10 mMol.

    Korant and his co-workers at Du Pont have found refractile changes and cell rounding not to be an indication of zinc cytotoxicity. Korant and co-workers showed the effects noted by Geist and associates, as well as by Merluzzi and associates could be induced by many noncytotoxic agents, including slight changes in carbon dioxide concentration and very minor changes to culture medium.(14)

    Other common cold-causing viruses inhibited by Zn2+ ions include herpes simplex viruses, reviewed by Eby and Halcomb,(15) and coxsackie(7) viruses. Zn2+ ions were shown by Merluzzi and co-workers not to have an antiviral effect on influenza-A.(12) Oxford and Perrin, and Cload and Hutchinson separately found Zn2+ ions to inhibit polymerase activity in influenza A and B,(16,17) although its effect on infectivity was not demonstrated.

    Zn2+ ions, but not zinc complexes, have antiviral properties, and those properties are documented for a number of important viruses unrelated to common colds. Avian myeloblastosis,(18,19) bacteriophages,(20) calicivirus,(21) equine herpes,(22) herpes simplex I and II,(23-30) polio,(31,32) encephalomyocarditis,(33,34) enterovirus,(35) foot-and-mouth disease,(36-38) mengovirus,(39) Rous sarcoma,(40) Semliki Forest,(41) Sindbis,(42) SV40,(43) tobacco mosaic viruses,(44) vaccina,(45,46) viroids and prions,(47) are all reported to have features controlled by Zn2+ ion usually at concentrations between 0.1 and 2.0 mMol without harm to cells.

    DNA is about 5000 times less susceptible to damage by Zn2+ ion than is RNA, suggesting zinc plays a role in predominant evolutionary selection of DNA, rather than RNA, as the bearer of the primary genetic information.(48)

    Inhibitors of viral protein cleavage are considered a possible method to control HIV infection.(49-51) Zn2+ ions, inhibitors of viral protein cleavage, have been found to have effects on Human Immunodeficiency Viruses 1 and 2 (HIV-1 and HIV-2).(49) Its nucleocapsid binds zinc and forms retroviral-type zinc fingers, which may have significance in the development of vaccines.(52) HIV-1 and HIV-2 protease are easily inhibited by Zn2+ ions at nearly normal zinc serum concentration(49) but without inhibition of virus infectivity.(14) Several virologists, including Korant, suggest viral replication or inhibition of various viral functions by Zn2+ ions may occur in many other viruses.

    Antibacterial and Antifungal Activity

    Zinc also has antibacterial activity in the mouth regarding bacteria unrelated to common colds. Zinc and other metal salts temporarily inhibited growth of Streptococci and Actinomyces as well as other dental caries producing bacteria.(53) Zinc chloride solutions of 20 mMol reduced plaque formation in heavy plaque formers(54) and reduced acidogenicity of dental plaque for several hours but were associated with undesirable taste and excessive oral drying.(55,56)

    Other reported therapeutic activity of zinc complements the record. Growth of Chlamydia trachomatis, a frequent cause of sexually transmitted diseases, was inhibited at 0.01 - 0.1 mMol Zn2+ ion in vitro.(57) Antibiotic activity of amniotic fluid is dependent upon zinc.(58) The list of zinc compounds used for topical antiseptic, antifungal, or astringent purposes in human beings or animals in the Merck Index includes zinc bacitracin, zinc acetate, zinc chloride, zinc carbonate, zinc citrate, zinc iodate, zinc oxide, zinc permanganate, zinc peroxide, zinc p-phenolsulfonate, zinc propionate, zinc salicylate, zinc stearate, zinc sulfate and zinc tannate.(59) Calamine lotion is mainly zinc oxide and has been used for many years as a topical protectant and astringent.(60) Zinc pyrithione is an active ingredient found in antibacterial, antifungal, and antiseborrheic shampoos.(61)

    Astringency

    Zn2+ ions are best known for their astringency. The basic effect of Zn2+ ions on many cells, including the immune system cells, seems related to their effects on cell plasma membranes, perhaps in a manner linked to and dependent upon astringency. Hydrated Zn2+ ions from loosely bound zinc complexes such as zinc chloride and zinc acetate (but not most tightly bound or lipophilic zinc complexes) are astringent. Zinc oxide is topically astringent but releases hardly any Zn2+ ions in a nonacidic medium. For Zn2+ ions, but not for other more tightly bound zinc compounds, cell rounding and refractile changes appear to result from its astringent, protective action on cell membranes, not from cytotoxicity. These changes often occur at about 0.1 mMol Zn2+ ions and at much lower concentrations for most lipophilic and strongly chelated zinc complexes.(12) These observations were interpreted as cytotoxicity for zinc and suggested a low 1:2 or 1:4 antirhinoviral therapeutic index for Zn2+ ions.(12,13)

    Other researchers, including those much more familiar with the appearance of the astringent action of Zn2+ ion on cell plasma membranes, place the index 10 or more times higher in vitro. Extracellular Zn2+ is a newly recognized host defense acting to stabilize and protect cell membranes.(1,62-67) All astringents, including Zn2+ ions, are locally applied protein precipitants having such low cell penetrability that action is essentially limited to cell surfaces and interstitial spaces (contraction, rounding, wrinkling and blanching in vitro). Permeability of cell membranes is reduced by astringents including Zn2+, but cells remain viable. Astringents harden the cement substance of capillary epithelium, inhibiting pathologic transcapillary movement of plasma protein and reducing local edema, inflammation, and exudation. Additionally, astringents reduce mucus and other secretions in tissues containing goblet cells and other secretory cells, causing affected areas to become drier and heal faster.(62)

    Many astringents, including Zn2+ ions, are irritants or caustic in high concentrations.(62) Astringents are used therapeutically to arrest hemorrhage by coagulating blood (styptic action) as well as to check diarrhea, reduce inflammation of mucous membranes, promote healing, toughen skin, and decrease sweating.(62) The astringent effects of zinc lozenges on immune system cells and mucosal tissues are harmless, and normal cellular appearance and function returns upon removal of Zn2+ ions. The astringent effects of Zn2+ on immune system cells and particularly its effects on mast cells as well as other immune cells and functions is important in understanding how Zn2+ affects common colds. Recommended concentrations of zinc acetate for use as a topical astringent are 0.2 to 2.0 percent (9 to 90 mMol Zn2+),(62) suggesting concentrations from zinc lozenges to be appropriate.

    From these observations, hydrated Zn2+ ions are observed not to enter or damage cells, and beneficial effects of Zn2+ ions occur exclusively at the cell membrane. By inference, oral absorption of topical Zn2+ ions through the oral mucosal membrane from zinc lozenges relies upon a non-lipophilic mechanism.

    Non-Specific Membrane Protection

    Perhaps the most consistently reported effect of Zn2+ ion on mammalian cells is membrane stabilization.(63) Zinc is present in many mammalian cell membranes, and stabilizing actions of certain steroid hormones on lysosomal membranes may be secondary to the effects of zinc.(63) The exact mechanism by which zinc stabilizes cell membranes is not clear and may be different for different membranes.(63) Hemolytic viruses, bacterial and animal toxins, components of activated complement, cytolysin (perforin), cationic proteins, and detergents have all been shown to induce a sequence of permeability changes at the plasma membrane that are in every case beneficially sensitive to changes in Zn2+ ion concentrations from normal levels up to 100 times normal serum concentration.(64-67) Membrane damage induced by a wide variety of hemolytic agents can be prevented by zinc ions at normal to 100 times the normal concentration of zinc found in human serum without harm to cells.(67) Within a range, as Zn2+ ion concentration is increased, the strength of protection also increases.

    The large dietary requirement for zinc cannot be explained by its known cellular and enzyme requirements, but it can easily be explained by requirement for high plasma membrane Zn2+ ions as protection against damage induced by cytotoxic agents of environmental origin. Zinc, present in human extracellular fluid at approximately 0.015 mMol, is likely to prevent damage only at rather low concentrations of cytolytic agent, and a higher concentration is required for protection against higher amounts of various cytolytic agents. Increasing concentration of extracellular divalent zinc may be useful in augmenting host defenses against a wide variety of cytotoxic agents and is considered by Pasternak to be a newly recognized host defense.(1,67)

    Similarly, calcium ions have been known since 1914 to protect cell membranes in vitro, but calcium ions are not useful in vivo since their concentration is under tight endocrine control. Elevated calcium ion concentration leads to adverse effects in vivo in excitable cells like heart, nerve, and muscle.(1) Concentrations of Zn2+ ions are not under endoctrine control, and their levels can be raised in tissues in a beneficial manner protecting tissues from some viruses and other cytotoxic agents. According to Pasternak, such action may well be the responsible mechanism for ameliorating effects of common colds as shown by Eby and others.(67)

    Cytolysin

    Cytolysin (perforin) is a strong pore-forming agent released by natural killer T-cell lymphocytes in response to virally injured cells.(65) The molecular structure of cytolysin has been described.(68) Cytolysin is released into virally infected tissues where it can cause cell membrane damage or cell death. Some believe cytolysin to be responsible for the increase in serous nasal drainage in common colds. In some respects cytolysin is analogous to the C9 component of complement. Zn2+ ion prevents pore formation by cytolysin between 0.01 and 0.1 mMol Zn 2+ ion, and blocks leakage from cells containing preformed cytolysin. The beneficial response from Zn2+ ions occurs within minutes. Removal of Zn2+ ions by chelation with EDTA in the presence of cytolysin restores some cytolysin pore-forming activity. The concentration of Zn2+ ions required to stop hemolysis of cells containing preformed pores is somewhat higher than the concentration required to prevent pore formation when all agents are introduced at the same time.(65)

    Complement

    The C9 component of complement has cell membrane-damaging properties capable of lysing or damaging cells. In the presence of 0.1 mMol Zn2+ ions, red blood cells do not lyse when complement C9 is added. The inhibitory action of Zn2+ ions appeared to be on the reaction or reactions occurring between the insertion of C9 and the damage-producing step and is completely reversed upon Zn2+ ion chelation.(69)

    Mast Cells

    Mast cells and basophils are commonly known to be mediators of Type I allergy and possibly also several symptoms collectively known as the common cold. Mast cells are discussed because of their historic association with common colds, because of their ubiquitous and mysterious nature, because mast cells are the current subject of extensive zinc research, and because mast cells are theorized by the present author to be potent antiviral and T-cell function-modulating cells. Mast cells have been implicated in allergy and common colds as causing tissue redness, inflammation, nasal congestion, release of mucus from goblet cells, nose and throat pain, tickling and itchiness, and, indirectly, coughing and sneezing.

    Mast cell derived reactions result from release of histamine, heparin, prostaglandins, SRS-A, and various powerful vasoactive amines from granules on the surface of mast cells, possibly including kinins. Mucosal mast cells are widely distributed in nasal, throat, and tracheal tissues and are believed to respond to viral antigens by degranulation. However, research shows histamine does not play a part in common colds.

    One product of mast cell-induced inflammation in response to rhinoviral attack is fever. One chemical mediator generated is endogenous pyrogen which increases concentration of prostaglandins from the hypothalamus, resetting the body's temperature to cause chills and fever.

    Hydrated Zn2+ ions prevent induced histamine release from mast cell granules(70) as well as release of all mast cell granule contents as Zn2+ ions stabilize mast cell plasma membranes.(1,64,67,70 ) Several receptors at plasma membranes might function as gates for transmitting information to intracellular space. In the case of mast cells, histamine-releasing agents appear to work through specific receptors at the cell membrane or by calcium antagonism. Masking receptor sites by membrane- impermeable zinc compounds could explain inhibition of release action,(70) but at least four mechanisms could also be operational. The granules of both basophils and mast cells also contain Zn2+ ions stored combined with histamine and heparin.(71) Concentrations are in the 4 to 20 mMol range for mast cell secretory granules,(72) which is 400 to 2000 times greater than Zn2+ ion concentration in human serum and identical to concentrations of Zn2+ ion in saliva from zinc gluconate or zinc acetate lozenges. Both human and rat tissue mast cells contain high concentrations (2.1 mg/million cells) of granule-associated zinc.(73) Perhaps some zinc binds histamine with heparin,(74) although research has shown this idea does not hold true in mast cells of rats.(75)

    Hydrated zinc ions stabilize cell plasma membranes and prevent induced histamine and vasoactive amine release from tissue mast cells.(1,64,67,72,76-78) Inhibition of histamine release begins at about 0.001 mMol concentration of Zn2+ ions in human beings and is greatest (80 to 100 percent inhibitory) at 0.1 mMol concentration.(76-79) This concentration of zinc is about 6.67 times higher than normally found in human serum. When histamine is released from mast cells, Zn2+ ions are also released in large amounts into surrounding tissues, perhaps acting as a source of local antiviral activity and T-cell immunostimulation. Zn2+ ions from zinc gluconate act to inhibit 100 percent of rat mast cell histamine release at 0.1 to 1.0 mMol concentration in typical or connective tissue mast cells, while much more is required for leukemic basophil cells.(80) Physiologic concentrations of Zn2+ ions inhibit release of histamine from human basophils and lung mast cells presumably by blocking calcium uptake induced by anti-IgE activation.(78) Zn2+ ions are a competitive antagonist of action of calcium ions in histamine secretion induced by anti-IgE. The zinc- histamine stability constant is log K1= 5.0 for both basophil and mast cell histamine,(78) but stability is sensitive to pH and is reported for pH 7.4. Similarly, Martell reports log K1= 5.4 for zinc and histamine.(81)

    Zn2+ ion has been proposed to be involved in catabolism of histamine, as zinc has been proven to interfere with pharmacologic effects of histamine leading to anaphylactic shock.(82-84) Berthon and others showed the complexes of histamine formed with Zn2+ ion and several naturally occurring amino acids in plasma to be neutral and unlike histamine itself. Histamine is inherently polar and exists mainly in a charged form because of protonation under the prevailing physiologic 7.4 pH. These neutral, mixed ligand complexes are thus thought to be capable of passively diffusing through lipid membranes into tissue where histamine can be catabolized.

    Dicarboxylic acid complexes of zinc, malate, malonate, tartarate, and maleate (log K1 = 2.0 to 2.8), were shown to be effective in catabolism of histamine,(83) but zinc aspartate and zinc glutamate (first stability constants log K1= 5.9 and 5.45 respectively) were not.(84) Berthon and Germonneau found zinc aspartate concentration in vitro needed to be raised 1000 times over normal levels to be more efficient than Zn2+ ion alone to favor zinc-mediated histamine diffusion into tissues.(84) Considering the stability constant of zinc and histamine is log K1 = 5.0, zinc complexes with stability constants above 5.0 cannot readily react with histamine to catabolize it. Zinc complexes with stability constants lower than 5.0 may reduce massive surges of histamine suddenly released into plasma in response to antigens, a variety of local stimuli, or general toxins. Mast cell Zn2+ ion complexation of histamine might explain absence of histamine from nasal lavages in colds (see below - Histamine or Kinins in Colds?).

    Hydrated zinc ions (Zn2+ ions) in mast cell granules are chemically or physically protected from strong zinc chelators, thus denying access to Zn 2+ ions by serum proteins and other zinc-complexing agents.(73) Such a unique property allows zinc to be delivered as Zn2+ ions or very lightly complexed zinc and not as strongly bound complexes of serum proteins to local virally infected tissues upon mast cell degranulation for use as a local, natural antiviral agent, an interferon-inducing agent, and a T-cell lymphocyte immunoactivator as well as a preventive of allergic responses, when sufficiently present in mast cell granules.

    Introduced nasally, zinc compounds including zinc chloride, sulfate, sulfocarbolate, oxide, stearate, and borate have been used to treat nasal catarrh for about 100 years.(85-91) Reports show intranasal zinc to be a mild, short-term nasal decongestant. Zinc electrically driven into nasal tissues provides beneficial relief from nasal allergy for up to one year, although treatment is painful (without cocaine pre-treatment) and may cause sloughing of nasal epithelium.(87-89)

    Histamine or Kinins in Colds?

    Histamine appears active in common colds, considering the widespread use of antihistamines to treat common cold symptoms, but such may not be true. The British Medical Research Council Common Cold Unit first reported histamine to be uninvolved in common colds in 1951, and antihistamines were worthless in common cold treatment.(92) Even so, nasal secretions from histamine-stimulated goblet cells in colds and allergy have been poorly studied until fairly recently.

    A wide-ranging amount of histamine (5 to 1,519 ng/ml, with a mean 91 ng/ml for non-allergic patients and 51/ng/ml for allergic patients) is found in nasal secretions, with the histamine amount being four times higher in men than women.(93) During symptomatic rhinovirus infections, analysis of nasal lavages shows kinins to be generated, vascular permeability increased, mast cells not participating, and neutrophils entering nasal secretions.(94)

    To test the hypothesis that viral respiratory infections cause symptoms by activating nasal mucosal mast cells to release mediators active on vasculature and mucosal glands, the presence of histamine in nasal secretions was assessed during natural colds and in laboratory-induced rhinoviral infections. Infection with rhinovirus and with influenza did not change these concentrations significantly. Histamine tended to be lower during viral infections.(95) Increase in kinins, but not histamine, in nasal lavages occurred in symptomatic common colds, suggesting mast cells and basophil activation do not occur during rhinovirus colds.(96) Increases in kinins correlated with increased vascular permeability, as monitored by increased concentrations of albumin in nasal lavages.(96) More information implicating kinins and not histamine in common cold symptomology has been obtained. (97-101) 2001 UPDATE: More on these important findings here.

    Rhinoviral illness of the respiratory tract enhances airway reactivity and predisposes allergic patients to develop late asthmatic reactions, which may be an important factor in virus-induced bronchial hyper responsiveness.(102) In infants with respiratory syncytial virus (RSV) infection, histamine and RSV-specific IgE were far more common in wheezing infants than in non-wheezing infants and adversely affected the outcome of RSV infections.(103)

    T-Cell Lymphocytes

    B- and T-cell lymphocytes are the main warriors in the defense of the nose. B-cells produce immunoglobins, antibodies that plug up cold-virus receptor sites and prevent viruses from attaching to cells of the nose and throat. Some cells become memory cells helping to prevent the recurrence of infection. T-cell lymphocytes, when summoned to the site of infection, turn into "killer cells" (perhaps with help from Zn2+ ions released by mast cells) which release cytolysin (perforin), opening pores in cell membranes and attacking and killing virus-infected cells. Other T-cells ("helper/inducer" cells) stimulate B-cells to produce more antibody. Still other T-cells become "suppressor" cells to shut off antibody production and killer-cell activity after viruses have been defeated. T-cells also release several other substances to help the body conquer infection, including macrophage activation factor, macrophage inhibition factor, interleukin 1 and 2, and interferon. Interferon prevents cell death caused by viruses and prevents viral replication.(92)

    In the common cold, Zn2+ ions have effects on local T-cell function not yet completely elucidated, and which are too complex for full discussion here. Emphasis here is on local mucosal tissue and cutaneous effects, as zinc serum level does not rise with administration of zinc lozenges in common colds. Zinc deficiency has been studied more than zinc excesses. Zinc deficiency is universally accepted as being harmful to the T-cell lymphocyte system and is potentially lethal in humans(63,104-107) because zinc transferrin is the body's only T-cell lymphocyte mitogen.(108) Its necessity in thymic T-cell lymphocyte function is well known.(109) Zinc is also necessary for transferrin synthesis(110) and a deficiency in either transferrin or zinc can cause profound T-cell immunosuppression. Zinc deficiency during prenatal life causes persistence of immunodeficiency for three generations in mice,(111) with predictably dire consequences for human beings. Golden and associates showed zinc-deficient children to have greatly increased susceptibility to severe infection, and restoration of thymic function and regrowth occurs only when large doses of zinc (2 mg zinc/kg body weight) are administered.(112) Whether the condition needing immunostimulation by zinc is malnutrition, HIV infection, AIDs, acute lymphocytic leukemia (ALL) or any other T-cell lymphocyte zinc immunodeficiency, daily dosage should be as described by Golden and associates for thymic stimulation and regrowth in malnutrition. Both the young and the elderly receive T-cell immunologic benefit with supplemental zinc in the 150 mg/day range.(113,114)

    At concentrations of 0.1 to 0.4 mMol zinc, a mitogenic response is induced in normal T-cell lymphocytes but not in leukemic lymphocytes.(115) This difference in response has been used to stimulate normal T-cell function in leukemia.(116) Zinc supplementation has been proposed to rectify T-cell anergy in pediatric Hodgkin's disease.(117) As little as 15 mg zinc from zinc gluconate after three weeks beneficially changes the helper (OKT4) to suppressor (OKT8) ratio by normalizing the suppressor population without increasing the absolute number of helper cells in healthy people, with no effect on leukemic T-cells.(115) One explanation for modulation of T-cell subset ratios is histamine induction of suppressor T-cells,(118) and Zn2+ ion inhibition of release of histamine, and consequently its effect on suppressor proliferation. As activation of T-cell lymphocytes requires 4 to 6 days for full effect (10 - 15 percent activated T-cells),(115) T-cell activity is a delayed response and comes into play late in common colds.

    T-cell activity is impaired after one month when healthy people take 300 mg zinc per day.(119) Large excesses of zinc are known to compete with copper and manganese for intestinal binding sites adversely driving down their absorption, resulting in several blood abnormalities.

    The zinc lozenge technique induces identical results in both normal people and in children immunosuppressed by chemotheraphy for treatment of acute T-cell lymphocytic leukemia (ALL). This similarity in response suggests zinc lozenges may help shorten colds in patients with other lymphocyte diseases including HIV infection and AIDS --- perhaps with prevention of life-threatening sequela. Much of the preliminary (pre-1984 Eby et al trial) research with zinc gluconate lozenges in the treatment of common colds was done in a small child suffering from ALL. The results appeared to be at least as good when treating colds in the ALL patient as when treating non-leukemic volunteers.

    Interferon Induction

    Working with mice in 1987, Reardon and Lucas reported Zn2+ ions to have T-cell mitogenic activities, inducing lectin-dependent cellular cytotoxicity of target cells and having interferon- inducing properties. Medical interests in zinc in immune function have been related to its requirements in the lymphocyte cell cycle, especially noted in zinc immunodeficiency diseases. Zn2+ is chemically the simplest compound known to activate lymphocytes to undergo cellular proliferation, and Zn2+ ions are the only ubiquitous cellular component functioning as lymphocyte mitogens in animals and as T-cell lymphocyte-specific mitogens in humans.(120,121) Splenic and lymph node lymphocytes from mice were activated with Zn2+ ions in vitro, as noted by several-fold increases in 3H-thymidine incorporation after 144 hours of culture. Optimal mitogenic concentration was 0.20 mMol Zn2+ ions. Lymphocyte responses were inhibited at 0.80 mMol concentration of Zn2+ ion.

    To determine whether Zn2+ ion could activate lymphocyte functions other than mitogenesis, interferon production was assessed. Splenic lymphocytes were stimulated by Zn2+ ions to produce interferon after an incubation period of 96 hours, but interferon was not produced at 48 hours. Interferon was interferon-gamma as the interferon was acid labile. Zn2+ ions produced 16 units of interferon, compared with 256 units of interferon when cells were stimulated by Concanavalin A. Optimal concentrations for interferon induction were 0.20 mMol for Zn2+ ion and 20 mcg/ml for Concanavalin A.(120,121)

    In agreement with the murine studies, Salas and Kirchner found Zn2+ ions to induce large amounts of human interferon in vitro in a study at the Institute of Virus Research, German Cancer Research Center.(122) Salas and Kirchner also confirmed Zn2+ ions to have a mitogenic effect on human lymphocytes, and Zn2+ ions from 0.05 to 0.5 mMol concentration (antirhinoviral concentration) to have the ability to induce large amounts of interferon- gamma. Using blood from several healthy human volunteers, maximum interferon induction was 120 and 128 IU/ml at 0.1 to 0.2 mMol Zn2+ ions. By comparison, 5 mcg/ml PHA induced 729 IU/ml interferon and 314 IU/ml respectively.(122) Concentrations considerably higher than 0.5 mMol Zn2+ ion appeared toxic for certain cells (as measured by the trypan blue test), and concentrations of Zn2+ ion significantly below 0.05 mMol did not induce interferon, although mitosis occurred. Kinetic experiments showed production of interferon to occur as early as 24 hours and reach its optimum by 96 hours. Adherent cells were required for the effect. Zn2+ ions were thus suggested to play a role in interferon induction in vivo explaining some human immune disorders characteristic of zinc deficiency, such as a decrease in natural killer cell activity and an increase in susceptibility to infection.(122) In mice, Gainer found impaired interferon action with zinc deficiency.(123)

    Anti-Inflammatory Action

    Although common colds are essentially viral infections of the nose, colds are characterized by tissue inflammation, large amounts of thin, serous nasal drainage, and thick goblet cell-derived nasal mucus. The effect of zinc on mast cells in vitro suggests zinc could impact upon mast cells in common cold therapy. Likewise, the effects of zinc on all mucosal immune system cells suggests zinc has immunomodulating effects which remain only partially understood. Most of the research on zinc and the immune system has focused upon deficiencies of zinc. In the case of treating common colds with zinc lozenges, zinc may be present in nasal and nasopharyngeal tissues in concentrations up to 50 times higher than normally found in serum, which may result in temporary, localized, mucosal immunologic functional changes. Zinc deficiency is often found in dermatologic diseases where inflammation is characteristic; and treatment with zinc (usually as zinc oxide) to control inflammation is common.

    With elevated concentrations of Zn2+ ions, the cement substance of capillary endothelium of all cells is known to become hardened so pathologic transcapillary movement of plasma protein is inhibited and local edema, inflammation, and exudation are thereby reduced. Mucus and other secretions are reduced in tissues containing goblet cells and other secretory cells, and the affected area dries and heals faster with added zinc ions.(62)

    Paradoxically, and beneficially in common colds, the functions of monocytes, neutrophils, and macrophages are inhibited by elevated concentrations of zinc(63,124,125) through cell plasma membrane stabilization, and these cells function maximally in moderate-to-severe zinc deficiency. Their antibacterial function is maximized automatically in vivo by the leukocyte endogeneous mediator (LEM) role of the liver, as bacterial growth typically is increased with normal zinc serum status.(126,127) Severe bacterial infections (and several severe viral infections) cause a rapid decline in body zinc pools by LEM to effectuate action by macrophages and polymorphonuclear cells (PMN), often accompanied by endogenous pyrogen (EP) -induced fever.(126) However, the functions of PMNs are greatly inhibited in cases of extreme malnutrition and these patients respond well to supplemental zinc.(128)

    LEM is not believed to be involved in common colds. Little fever or difference in zinc serum concentrations has been noted between zinc and placebo-treated patients in common cold clinical trials in relatively unstressed patients. Upon stabilization of cellular and lysosomal membranes of white blood cells with Zn2+ ion in common cold treatment, nasal inflammation quickly subsides. To assess LEM action in colds accurately, zinc serum levels of infected persons receiving zinc lozenges should be compared with an uninfected control group treated with zinc throat lozenges.

    Zinc, often as zinc oxide, has long been used to inhibit inflammation of the skin (e. g., diaper rash, other dermatitis) in a safe and effective manner in over-the-counter preparations. Inhibition of nasal inflammation by zinc is not seen as especially different, and zinc oxide ointments applied to the nares are effective in temporarily drying nasal tissues in allergy or common colds without reduction in duration of the illness. Failure of zinc to inhibit release of mucus from nasal goblet cells when zinc is effective in other inflammatory responses would be viewed as an anomaly. Nasal mucus dries up quickly, and goblet cell membranes are also stabilized. Mast cells are known to be stabilized by zinc. Zn2+ ions prevent the release of histamine to trigger goblet cell's release of mucus.

    Zn2+ ion has very potent and rapid-acting human prostaglandin metabolite-inhibiting properties (to 90 percent or more) at 0.01 to 0.1 mMol,(129) that may be responsible for reducing headaches, pain and inflammation in common colds.

    Zinc, Stress, and Common Colds

    Recently the relationship between stress and common colds has been a subject of interest. Patients with varying degrees of stress, from low to high, were administered rhinoviruses, and the results were compared to levels of stress in their daily lives.(130) Persons having more stressful lives were significantly more susceptible to colds. Zinc serum level has long been known to fall in highly stressful situations through LEM action, wherein the liver sequesters zinc from the blood within minutes,(126,127) and it should not come as a surprise that highly stressed persons have lower zinc serum levels and generally more infections.

    Overview of Effects of Zn2+ Ions in Common Cold Therapy

    Zn2+ ions have a number of effects in vitro of interest in common cold therapy. Their potent in vitro antirhinoviral effects are of foremost interest and may be observed in vivo in colds treated with zinc lozenges releasing Zn2+ ions. Zn2+ ions strongly stimulate interferon production within 24 hours and zinc lozenges may prompt interferon release in colds. Zn2+ ions are also necessary for the functioning of the immune system and the growth of immune cells. Zn2+ ions are strongly astringent and may appear harmful to immune cells to observers unfamiliar with its harmless astringent rounding and blanching effects.

    Concentrations up to 100-fold normal serum concentration have been used in cell membrane stabilization studies, almost always without lasting harm. Addition of Zn2+ ions to cells undergoing hemolysis by many agents stops cell membrane leakage by closing membrane pores and has been shown to protect tissues in vivo. Mast cell plasma membranes are readily stabilized by Zn2+ ions, and the outflow of histamine, heparin, and all mast cell vasoactive agents, perhaps including kinins, is immediately halted. Zn2+ ions help metabolize histamine and may explain the relative absence of histamine in common colds. Increased nasal tissue concentrations of Zn2+ ions may occur naturally from mast cells in upper respiratory infection or exogenously by use of lozenges releasing Zn2+ ions in common cold therapy.

    Pores in capillary walls are closed by Zn2+ ions, and Zn2+ ions may reduce or prevent movement of monocytes and lymphocytes into infected tissues. Closure greatly enhances the movement of Zn2+ ions over long distances through biologically closed electric circuits (see Chapter 3).(131) Once cell pores are closed by Zn2+ ions, pores tend to remain closed in vitro, appearing in vivo as a resistance to relapse. Even so, nasal mucus flow and tears caused by crying are neither stopped nor prevented, even with extensive use of zinc gluconate lozenges, suggesting two separate mechanisms of action on goblet cells.

    Elevated concentrations of Zn2+ ions may inhibit activated PMN and macrophage mobility and function, but not their viability. Since fever subsides rapidly, interleukin-1 production may be inhibited by Zn2+ ions. Although lymphocyte movement into infected tissues may be impaired by Zn2+ ion capillary wall pore closure, both local B-cell and T-cell lymphocyte functions are believed to be beneficially affected, and perhaps T-cells are activated.



    Chapter 2 References

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    61. Ibid; 1153.

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    64. Bashford CL, Alder GM, Menestrina G, et al. Membrane damage by hemolytic viruses, toxins, complement, and other cytotoxic agents - a common mechanism blocked by divalent cations. The Journal of Biological Chemistry. 1986;261: 9300-9308.

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    106. Prasad AS. Discovery and importance of zinc in human nutrition. Federation Proceedings. 1984; 43:2829-2834.

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    Chapter 3. Zinc Lozenge Method of Treating Colds

    Executive Summary Chapter 3 discusses the rationale for application of hydrated Zn2+ ions to the oral cavity, rather than the nose. The biologically closed electric circuit (BCEC) between the interior of the mouth and the interior of the nose is described. The mouth-nose BCEC transports Zn2+ ions one-way only; from the mouth into virally infected tissues of the nose, and explains why zinc applied directly to nasal tissues is ineffective. Once within infected nasal tissues, Zn2+ ions produce beneficial effects that shorten common colds. The zinc ion availability (ZIA) concept is introduced. ZIA is crucial to understanding the variations in results reported in the clinical trials described in Chapter 4. Zinc lozenge efficacy depends totally upon lozenge ZIA, which in turn depends upon the concentration of hydrated Zn2+ ions in saliva over the time of lozenge dissolution and treatments per day. The ZIA concept is an application of Fick's laws of permeability as they are extended to include flow of charged particles in bioelectric fields.

    Zn2+ ions are highly antirhinoviral both directly and through stimulation of interferon production. Zn2+ ions protect cell membranes in vitro as effectively as interferon. If a way to introduce and keep Zn2+ ions in the vicinity of superficial columnar cells of the nasal turbinate epithelium (the cells thought to be infected by rhinoviruses in common colds) could be found, then Zn2+ ions could inhibit rhinoviral replication and protect cells from rhinoviral attack in vivo. It may seem less direct or implausible to apply zinc to oral tissues and not nasal tissues, but administration to the nose is known not to reduce the duration of common colds. Zn2+ ions applied to the oral and oropharyngeal mucous membranes appear to be readily absorbed into the oral membranes where Zn2+ ions migrate into nasal tissues by diffusion, osmosis, and electrophoretic force. Saliva is well known to be continually absorbed into oral and oropharyngeal tissues.

    Nasal Administration and Systemic Absorption

    Foreign substances introduced intranasally are rapidly cleared by mucous secretions and require frequent administration (every 10 to 15 minutes)(1) to keep substances in the nose on top of nasal mucus, cilia and mucous membranes, but not within nasal tissues. Nasal mucus is constantly being excreted, flowing outward from tissues and carrying viruses, antigens, dust, and medications into the throat by action of the cilia. Zn2+ ion diffusion into these infected tissues by nasal administration against the flow of mucus and mouth-nose electrical circuit is difficult if not impossible. Zinc nasal spray does not result in clinical reduction in duration of common colds, even when 10 mMol zinc gluconate nasal spray is administered every 15 to 30 minutes, although zinc does provide a temporary decongestant effect.(2) Similarly, zinc sulfate nasal sprays have been shown by Derek Bryce-Smith at the University of Reading in Great Britain to have a mild nasal decongestant effect with no effect on the duration of common colds.(3) Considerable evidence (discussed in Chapter 2) from before 1900 to about 1960 shows that zinc compounds applied to the nostrils were weak nasal decongestants unassociated with reduction in common cold duration.

    Additionally, oral doses of zinc do not produce sufficiently high concentration in the nasal tissues to affect common cold duration, unless the oral doses are extremely large (several grams), and these large doses may be somewhat toxic to blood-forming tissues and other organs.

    Oral Cavity Absorption

    A much more effective method of introducing Zn2+ ions into nasal tissues has been developed using zinc throat lozenges. This use results from a serendipitous observation in 1979 of a near-instantaneous relief from a cold after use of a 50-mg zinc as zinc gluconate lozenge in a leukemic 3-year-old child.(4) The oral cavity -- and oropharyngeal tissues generally -- being part of the digestive system absorb, rather than repel, nutrients and other soluble substances remaining in contact with them. Absorption through these mucous membranes has been likened to absorption by other digestive system tissues and particularly to intestinal tissues, while nasal tissues appear to be more akin to ciliated, involuted skin. General absorption of drugs kept in the mouth consists of a process of dissolution, followed by transport of dissolved drug and other soluble ingredients across mucosal membranes into tissues and usually into general circulation.(5)

    Drugs must traverse several biologic membranes before reaching the site of action. In the oral cavity there are two regions, buccal and sublingual, where the membranes are very thin and have a copious blood supply.(6) Sublingual administration of Zn2+ ion entails the placement of the lozenge under the tongue for its ultimate absorption into the systemic circulation and is not really practical because of the large size of the lozenges. Buccal administration of Zn2+ ion is ordinarily accomplished by placing the lozenge between the cheek and gums. Drugs, including Zn2+ ions given by sublingual and buccal administration enter the circulation directly and are carried to oral, facial, nasal, and body tissues before passage through the liver6 where Zn2+ ions may be sequestered by leukocyte endogeneous mediator (LEM) action.(7,8) Venous drainage from the oral cavity goes directly to the heart.(6) Estimates of in vivo availability of charged species from static in vitro observations, such as 11 percent Zn2+ ions in saliva(9 and 2 to 8 percent Zn2+ ions in serum,(10) may or may not be applicable in vivo because of numerous factors including pH, temperature, and electromotive forces acting on charged particles. In common cold therapy with zinc lozenges, oral-nasal potential difference accelerates absorption of Zn2+ ions from saliva, ionization of Zn2+, and motility of Zn2+ ions.

    With highly soluble substances such as ionizable zinc compounds, the rate of permeation across biologic membranes, not dissolution, is the rate-determining step. The rate of permeation is dependent upon size, relative aqueous and lipid solubilities, and ionic strength.(5,6) Like most biologic membranes, oral mucosal membranes are largely lipoidal in character. Hence, good lipid solubility of a drug is an important factor in assessment of its absorption potential. Many drugs are either weakly acid or weakly alkaline compounds, and in solution, depending on pH value, exist as ionized or un-ionized species. Un-ionized neutral species are more lipid-soluble and hence more readily absorbed in the absence of an electromotive force (EMF). Charged species depend almost totally upon concentration applied, time applied, and charges of membranes and ionized solute and are absorbed through passive transfer aided or repelled by electromotive forces.(5,11,12) Endothelial cells themselves are permeable for lipophilic substances but not for hydrophilic substances.(5,11)

    A published Zn2+ ion oil/water partition coefficient has not been found but is expected to be extremely low or zero. Salivary glycoproteins coating oral mucosa are known to carry negative charges and are an important binding site for cationic substances, such as Zn2+, in the mouth.(5) The latter, including Zn2+ ions, pass through capillary walls through interepithelial spaces, called stomata, pores or leaky junctions and are attracted to electronegative oral mucous membranes.(11) Once Zn2+ ions enter the oral mucous membrane, they appear to follow preferential pathways in biologically closed electric circuits leading to the nose where they exert beneficial effects, and/or Zn2+ ions may be mechanically transported. Therefore, the main factors in determining the amount of Zn2+ ions transferring through oral mucosal membranes are salivary concentration of Zn2+ ions, and the time oral and oropharyngeal mucosal membranes are exposed to Zn2+ ions, as well as electrical effects, which are presumably about the same in all people.

    The fate, route, movement, binding, and concentration of soluble zinc, including Zn2+ ions, once absorbed into oral and nasal tissues using this method have not been determined. With topical treatment by zinc gluconate or acetate lozenges, an increase in Zn2+ ion serum concentration in oral, throat, and nasal tissues appears both possible and probable. Capillary membrane pores are known to be sealed by Zn2+ ions aiding in the transport of Zn2+ ions over long distances.(11) However, Zn2+ ions from zinc gluconate throat lozenges do not appear in nasal mucus after use of one lozenge in amounts different from placebo during the first few hours after administration in well, non-allergic patients as determined through use of furnace analysis atomic absorption spectrophotometry.(13) Such results are not unexpected, as no evidence exists of goblet cells selectively taking up Zn2+ ions to mirror lymph or plasma zinc content so quickly.

    Anecdotal observation of weak local tissue sensations while using zinc gluconate lozenges suggests a way to track movement of zinc into tissues. Some patients say the zinc seems to migrate: upward into the nose, eyes, and ears where drying actions on tissues can be observed; then into facial tissues, and temples where it can be felt; then downward into the throat, pharynx, esophagus, and stomach. A drying effect of Zn2+ ions in the throat and on vocal cords of singers having respiratory allergies who use zinc gluconate lozenges results in improved ability to sing, showing movement of zinc or its drying effects into the larynx and trachea.

    Although the means by which zinc moves into these tissues remains obscure (perhaps diffusion, osmosis, and electrophoresis), lymphatic circulation more than venous circulation of Zn2+ ions out of these tissues is deduced. For example, if zinc lozenges are used throughout the day and at bedtime, then zinc concentration in nasal and nasopharyngeal tissues may become high, and movement of zinc out of these tissues stops when lymph movement stops. Consequently, Zn2+ ions remain in contact with virally infected tissues overnight without lymphatic drainage. Colds are most often observed to disappear during nighttime sleep, which is a time when lymphatic circulation is arrested. Upon arising, the mouth and nose are often unusually dry. Oral drying follows the use of highly ionizable zinc compounds (not tightly bound zinc) and may be explained by antirhinoviral, antihistaminic effects, cell membrane stabilization, anti-cytolysin (perforin) effects, astringency, and other anti-inflammatory properties associated with Zn2+ ions.

    Because the content of zinc in plasma (mostly tightly complexed with albumin, transferrin, and other blood proteins) is about 1 mg/ml and in most tissues it ranges from 11 to 150 mg/g, obviously an active or facilitated uptake exists, but little is known of the nature of the uptake mechanisms of various cells.(14)

    Mouth-Nose Electric circuit

    According to B. E. Nordenström of the Karolinska Institute in Stockholm, ample evidence exists for circulatory circuits with the ability to move electrically charged metallic ions long distances.(11) Using a digital voltmeter, the present author has measured a 80 to 120 millivolt potential difference between the oral cavity and the interior of the nose, with the mouth acting anodic. A mouth-nose current may also be inferred using an ohm-meter. Reversing mouth and nose leads changes readings usually by about 10,000 ohms (10,000 ohms one way and 20,000 ohms the other way). Resistance fluctuates by 100 to 300 ohms with the respiratory rhythm. Similar measurements while dissolving zinc acetate lozenges and at various times up to an hour after dissolution showed the same results. If confirmed by others, these observations may be the most readily observable examples of biologically closed electric circuits (BCEC) in human beings.

    A surplus of negative charge always characterizes the surface of cells as well as most viruses, although some tissues have greater electronegativity than others. The source of electrons in the mouth may be from loss of protons from mucoproteins passed from oral tissues into saliva or the potential-inducing, battery-like, action of the tongue. Nordenström has shown muscles, such as the tongue, and injured or infected tissues to generate potentials of the magnitude noted by Eby in the mouth-nose circuit.(11)

    Positively charged Zn2+ ions appear to migrate along preferential pathways between the mouth and nasal tissues as well as into other non-oral local tissues and venous and lymphatic drainage pathways. Perhaps some fraction of Zn2+ ions migrates the long distance (aided by Zn2+ ion-induced capillary membrane pore closure) from the oral cavity into nasal tissues via preferential pathways in BCEC, and some migrates by mechanical transport. Intranasal Zn2+ ions should provide an antirhinoviral effect, induce interferon production, and dry nasal tissues. These findings suggest passive absorption (mechanical transport, diffusion, filtration, and osmosis) of Zn2+ ions from mouth into the nose to be aided by electrophoresis.

    Along with the strong repelling effects of nasal mucus and cilia on foreign substances introduced to the nose as noted by Aoki1 and many others, the voltage differential repels intranasally introduced Zn2+ ions from mucosal surfaces, further explaining inefficacy from 10 mMol zinc gluconate nasal sprays (see Chapter 4.B.1.).

    Fick's First Law

    Linearity in pharmaceutical dose-responsiveness is usually attributed to passive diffusion of neutrally charged lipophilic substances across biologic membranes according to Fick's first law and to mechanical transport by the arterial, venous, and lymphatic systems. Toxicity from intracellular accumulation of zinc from lipophilic or strongly bound complexes of neutrally charged zinc(15,16) may be quite real, suggesting only non-toxic, astringent, 100 percent hydrated Zn2+ ions should be provided from zinc lozenges.

    Passive diffusion happens when drug molecules exist in high concentration on one side of a membrane and lower concentration on the other side. Diffusion occurs in an effort to equalize drug concentration on both sides of the membrane in those cases where the rate of transport is proportional to the concentration gradient across the membrane. When the volume of fluids is fixed, the movement of drug across a membrane can be described in terms of Fick's laws.

    Fick's first law states the rate of diffusion or transport across a membrane is directly proportional to the surface area of the membrane and to the concentration gradient and is inversely proportional to the thickness of the membrane.(6) The general expression for Fick's first law of diffusion is dm/dt = -DAdc/dx where m is the quantity of drug or solute diffusing in time t, dm/dt is the rate of diffusion, D is the diffusion constant, A is the cross-sectional area of the membrane, dc is the change in concentration, and dx is the thickness of the membrane.(6) A change in any of these variables will alter the rate of transport of drug into the blood over a given time.

    Drugs are rapidly absorbed through thin membranes such as the oral mucosa. In the assessment of absorption potential of drugs, various experiments using biologic membranes have been conducted to demonstrate Fick's first law. Experiments are carried out at different mucosal concentrations of drugs to determine the response to treatment.

    Constancy of amount transferred per unit time per unit concentration over a wide range of mucosal solution concentrations indicates passive transfer of drug and compliance with Fick's first law.(5,6) Passive transfer refers to a free diffusion across a membrane composed of channels of various sizes without biologic activity or electrochemical processes being involved.(5,6)

    As the concentration gradient across the barrier is increased, the flux across the barrier increases in direct proportion.(5,6) By varying the amount of drug given in vivo in a given time drug concentration can be varied. Drug absorption is ascertained by blood and urinary analysis or by response to treatment.(5,6)

    A linear relationship between different amounts of drug given in a given period and the degree of improvement suggests absorption under Fick's first law applies in vivo.

    In common cold therapy with Zn2+ ions, ectrophoretic effects alter Zn2+ ion motility and absorption under Fick's laws, which increases absorption over uncharged substances. Fick's laws include electromotive forces acting on electrically charged particles.(11,12) Hydrated Zn2+ ions move across membranes and through living tissues under Fick's first and second laws.(11) Hydrophilic substances, including Zn2+ ions, pass between cells through interepithelial spaces called stomata, pores or leaky junctions; in the case of metallic ions, they also follow preferential pathways in BCEC.(11)

    Positively charged metallic ions are transported in charged clusters reacting with electronegative cell membranes at short distances or at long distances when capillary cell membranes are closed by high concentrations of Zn2+ ions.(11) Negatively charged complexes are repelled from cell surfaces and viruses which are always electronegative.(11) In contrast, neutrally charged complexes are not aided or repelled by electric fields and their movement depends only upon diffusion and mechanical transport.(11)

    Ionic Diffusion

    Starting with the authoritative works of Lehninger,(17) Bockris and Drazic,(18) Newman,(19) Nobel(20) and others, in the field of energy exchanges in chemical reactions, Nordenström developed the concept of biochemical reactions in BCEC to include ionic diffusion. Ionic diffusion in BCEC occurs according to Fick's first law which can also be written as -Q = D (dc/dx) in which Q, in mole per m2t, is the quantity of ions traversing a unit area of solvent per unit time. The factor D is the diffusion coefficient, which expresses (in 1/ m2t units) the proportional ability of an ion to diffuse a distance dx in a solvent at a concentration difference dc. In a non-steady state this concept can often be expressed as x = constant times the square root of Dt, where D = diffusion constant (in 1/m2t) and t = time (seconds).(11)

    In Nordenström's eloquent words, in the following equation representing a nonstatic condition, the amount of material Q passing a unit area A per second over distance dx leads to QA - (Q + dQ/dx x dx) A = dc/dt x Adx showing the inflow of material Q through the area A, minus the rate of Q though the area A over the distance dx, equals the concentration change per unit time though the distance dx through the same area A. This equation can be simplified to the continuity equation -dQ/dx = dc/dt. Substituting Fick's first law into the continuity equation results in Fick's second law dc/dx = D(d2c / dx2), which in a three-dimensional distribution, gives dc/dt = D(d2c / dx2 + d2c / dy2 + d2c / z2). This equation describes the function of local administration of an ionic drug, such as Zn2+ ions, during application of experimental direct current or within a BCEC in living tissue.(11)

    In common cold treatment with zinc lozenges, ionic motility and total diffusion calculations can be used in theory. However, for practical use in comparing the efficacy of different zinc lozenge formulations against the duration of common colds, Fick's laws can be greatly simplified by assuming constancy between patients for the cross-sectional area of the oral mucosal membrane, its thickness, facial three-dimensional geometry, BCEC configuration, mouth-nose EMF (and direction), as well as many other variables excluding all but the number of doses, the lozenge dissolution time, the electronic charge of the zinc species and the initial zinc concentration. Perhaps the largest error introduced by these assumptions results from the differing characteristics of small children and adults. By introducing time, rates are converted into totals.

    Zinc Ion Availability (ZIA) Values

    The notion of zinc ion availability (ZIA) used here is derived from Fick's first and second laws of diffusion, but ZIA does not measure the amount of Zn2+ ion absorbed across biologic membranes. By calculating ZIA values for the various studies, the finding of linearity in response to treatment (see Figure 19 in Chapter 5) suggests ZIA to be a relative determinant of the amount absorbed in compliance with Fick's laws of membrane diffusion. Therefore, ZIA is defined as the potential for daily absorption of Zn2+ ions into oral and oropharyngeal mucosal membranes at pH 7.4 between lozenges having several different characteristics, or ZIA = KZiT, where K = 0.7697, and Zi = initial concentration of Zn2+ ions, and T = time.

    For calculation of daily ZIA for comparative purposes between lozenge formulations, the daily ZIA value equals the constant 0.7697, times lozenge zinc dosage (mg), times fraction as Zn2+ ion at pH 7.4 (initial fraction before precipitation of Zn2+ ions by salivary proteins and absorption into oral mucosal membranes), times oral dissolution time (minutes) of lozenges, times lozenges used per day, divided by volume (ml) of saliva generated (numerically equal to total saliva generated minus lozenge weight in grams corrected for lozenge specific gravity) during each oral dissolution. Some of the facts can be determined only by studying the intra-oral dissolution/expectorations of zinc-laden saliva, or zinc-laden saliva. Linear, or at least uniform, lozenge dissolution rates occur in all lozenges tested (see Chapter 7).

    To further illustrate, the ZIA value of the original 1984 Eby lozenges is 100. The 660 mg lozenges containing 23 mg zinc gluconate initially released 30 percent Zn2+ ion at pH 7.4 (see Figure 1 in Chapter 1). The constant K is 0.7697. Lozenges dissolved in 30 minutes. Lozenges were used 9 times a day. Lozenges generated 15 ml zinc-laden saliva per application. When multiplied together, they equal +129.92K. To set the ZIA to 100 for the Eby lozenges as a standard; K, therefore, equals 0.7697 ml / minutes x mg x doses/day.

    The ZIA formula and concept are used throughout the remainder of this handbook to compare critical performance criteria of different zinc lozenge formulations. Lozenges with equal ZIA values, within a reasonable range centered on the above example, theoretically will have equal efficacy against colds, although initial Zn2+ ion concentrations should be more than 5 mMol.

    In the event more strong zinc chelator is present than needed to bind all Zn2+ ions and to otherwise produce a ZIA value of zero, the ZIA value is considered to be negative.

    Mathematics of Common Cold Duration

    Review of common cold studies shows results to have been expressed in various terms, with most of them showing the effect of treatment on symptom severity. Techniques include mean clinical scores, symptom clinical scores, total nasal mucus weights, total number of facial tissues used, and other subjective measures of wellness.

    More recently, half-lives of common colds and weighted average durations of common colds were shown to be appropriate means of common cold analysis when the rate of decay is exponential.(4) According to Gwaltney, one-half of untreated rhinovirus colds are over in one week, three-fourths are over in two weeks, while seven-eighths last three weeks or less, and so forth.(21) Therefore, the half-life (H) of untreated colds is 7 days. With each passing week, one-half of remaining colds disappear.

    Figure 2.  Effect of different half lives on colds Figure 2. Effect of different half-lives on percent of patients with symptoms on various days, showing weighted average durations (arrows).

    The effect of a hypothetical zinc and placebo treatment having different half-lives on percentage of patients during first week of treatment and projected values beyond the week of treatment are shown in Figure 2. Consider the situation where 50 percent of patients are well by day 2.2 with zinc treatment and by day 7 with placebo; 75 percent are well by day 4.4 with zinc treatment, and by day 14 with placebo; 86.5 percent are well by day 6.6 with zinc treatment, and by day 21 with placebo. Using half-life theory, the expected number of patients recovered can be projected beyond duration of studies. Estimates after the week of treatment are predicated upon half-life of colds continuing to decay at same rate as during the week of treatment.

    Related to the half-life of common colds is the average duration. Although average duration is not the same as half-life, they are frequently confused with each other. The average duration is equal to the number of days colds persist, where the sum of days is taken over the collection of patients, divided by total number of patients. The average duration is mathematically related to half-life (H) of common colds. For common colds decaying at a set exponential rate, average duration of common colds is provided by the mathematical expression where N is initial number of patients, and H is half-life of colds observed in study group.

    Average duration of colds by half-lifes

    The expression simplifies to H/ln 2, and ln 2 equals 0.6931. Therefore, once the half life (H) is determined and the decay rate is found to be exponential, the average duration can be directly determined. For example, zinc-treated colds having a half life of 2.2 days have an average duration of 3.2 days, and placebo-treated colds with a half-life of 7 days have an average duration of 10 days. Arrows in Figure 2 show weighted average duration. Differences in weighted average duration between treated and untreated colds directly follow. This method is not reliable for colds not decaying at an exponential rate.

    Other methods of determining average duration must be used for non-exponentially decaying colds, which would involve observing the duration of each cold, an arduous task for placebo-treated colds. In the case of nonexponentially decaying colds, half-life analysis and comparison of decay rates (plotted as the number of colds remaining on each day of the study) are probably sufficient.

    The above method of determining half-life and estimating average durations for exponentially decaying common colds should be adopted as the favored means to measure effects of zinc lozenges on shortening the duration of common colds. Half-life and average duration analyses may be used to supplement all other methods of measuring effects of treatments including mean clinical scores, total nasal mucus weights, and number of facial tissues used. Each of the reports in Chapter 4 have been re-analyzed using published facts and factual details from lozenge manufacturers, and half-life and average reductions (or increases) in duration have been calculated using all the available information.

    Chapter 3 References

    1. Aoki FY. Distribution and removal of human serum albumin - Technetium 99m instilled intranasally. British Journal of Clinical Pharmacology. 1976;3:869-878.

    2. Eby GA, Davis DR, Halcomb WW. Effect of zinc orotate lozenges with zinc gluconate nasal spray in common cold treatment - a double blind study. Unpublished data, 1984.

    3. Bryce-Smith D. Spray preparations for respiratory tract infections. European Patent Application 381522, August 8, 1990.

    4. Eby GA, Davis DR, Halcomb WW. Reduction in duration of common cold symptoms by zinc gluconate lozenges in a double blind study. Antimicrobial Agents and Chemotherapy. 1984;25: 20-24.

    5. Wadke DA, Serajuddin ATM, Jacobson H. Preformulation testing. In: Lieberman HA, Lachman L, Schwartz JB, eds. Pharmaceutical Dosage Forms: Tablets Volume 1. New York: Marcel Dekker, Inc.; 1989.

    6. McGinity JW, Stavchansky SA, Martin A. Bioavailability in tablet technology. In: Lieberman HA, Lachman L, Schwartz JB, eds. Pharmaceutical Dosage Forms: Tablets Volume 2. New York: Marcel Dekker, Inc; 1989.

    7. Subcommittee on Zinc, Committee on Medical and Biological Effects of Environmental Pollutants, Division of Medical Sciences, Assembly of Life Sciences, National Research Council. Zinc. Baltimore:University Park Press; 1979;305.

    8. Beisel WR, Pekarek RS, Wannemaker RW Jr. Homeostatic mechanisms affecting plasma zinc levels in acute stress. In: Prasad AS, Oberleas D eds. Trace Elements in Human Health and Disease. New York: Academic Press; 1976;87-102.

    9. Hurford SR, Smith GL, Williams DR, et al. Metal ions and their interactions with biological fluids: speciation of trace metals in saliva. Rev. Post. Quim. 1985;27:423-424.

    10. Prasad AS, Oberleas D. Binding of zinc to amino acids and serum proteins in vitro. Journal of Laboratory and Clinical Medicine. 1970;76:416-425.

    11. Nordenström BE. Biologically Closed Electric Circuits. Clinical, Experimental and Theoretical Evidence for an Additional Circulatory System. Stockholm:Nordic Medical Publications; 1983; 112-172.

    12. Gupta D, Ho PS. Some formal aspects of diffusion. In: Gupta D, Ho PS, eds. Diffusion Phenomena in Thin Films and Microelectronic Materials. Park Ridge, NJ:Noyes Publications. 1988;2.

    13. Gwaltney JM Jr. University of Virginia School of Medicine, Charlottesville, VA. Unpublished data, 1984.

    14. Jackson MJ. Physiology of Zinc: General Aspects. In: Mills CF, ed. Zinc in Human Biology. New York: Springer-Verlag; 1989.

    15. Merluzzi VJ, Cipriano D, McNeil D, et al. Evaluation of zinc complexes on the replication of rhinovirus 2 in vitro. Research Communications in Chemical Pathology and Pharmacology. 1989;66: 425-440.

    16. Geist FC, Bateman, JA, Hayden FG. In vitro activity of zinc salts against human rhinoviruses. Antimicrobial Agents and Chemotherapy. 1987;31: 622-624.

    17. Lehninger AL. Biochemistry. 2nd ed. New York: Worth Publishing, Inc.; 1975.

    18. Bockris O'M, Drazic D. Electro-Chemical Science. London:Taylor & Francis; 1972.

    19. Newman J. Electrochemical Systems. Englewood Cliffs, NJ:Prentice-Hall; 1973.

    20. Nobel PS. Introduction to Biophysical Plant Physiology. San Francisco:W.H. Freeman & Co.; 1974;92.

    21. Gwaltney JM Jr. Rhinovirus. In: Mandell GL, Douglas RG Jr, Bennett JE, eds. Principles and Practices of Infectious Diseases. New York:John Wiley & Sons; 1979; 1124-1134






    Chapter 4. Effects of Zinc Lozenges on Duration of Common Colds

    Executive summary Chapter 4 describes three possible effects of zinc lozenges upon common colds. Lozenges containing very weak complexes of zinc release positively charged zinc (hydrated Zn2+ ions) at pH 7.4, resulting in positive ZIA values. As the concentration of Zn2+ ions and the time over which they are applied are increased, duration of colds and severity of cold symptoms are proportionately reduced. Use of lozenges having a ZIA value of 25 reduced the average duration of colds by 1.6 days. Use of lozenges having a ZIA value of 44 reduced the mean clinical score and average duration and nasal secretion weights of colds by 4.8 days. Use of lozenges having a ZIA value of 100 reduced the duration and severity of common colds by 7 days.

    Lozenges containing strongly complexed zinc release neutrally charged zinc complexes (ZnL0) at pH 7.4, resulting in a ZIA value of zero. Lozenges having zero ZIA values have no effect upon either symptom severity or duration of common colds.

    Lozenges containing strongly complexed zinc with strong ligands in molar excess release negatively charged zinc complexes (ZnLNN-) at pH 7.4, resulting in negative ZIA values. Lozenges having negative ZIA values increase both the severity and duration of common colds.

    Divergence in results between clinical trials of the eight distinctly different proprietary zinc lozenges reviewed is completely reconciled when zinc ion availability (ZIA) values are considered.

    Lack of knowledge of the availability of Zn2+ ions by both the authors of the following studies and the independent manufacturers of lozenges used in the authors' studies has seriously impeded clinical research involving lozenges releasing Zn2+ ions as treatment and cure for the common cold. Some clinical researchers, not knowing the lozenges supplied by manufacturers contributed few or no Zn2+ ions, came to believe "zinc didn't work."

    The purpose of the following reviews of the clinical studies is to bring to light the amount of Zn2+ ions available from study lozenges (ZIA values of treatments) and to compare those values with the reduction in duration in common colds.

    Using this approach, it becomes obvious that total Zn2+ ions -- and not total zinc compounds -- are effective in reducing the duration of common colds. It will also be shown the amount of reduction in duration is directly related to the amount of Zn2+ ions available as calculated using ZIA values, reflecting Fick's laws. Salivary Zn2+ ion concentrations throughout the following reviews are given at pH 7.4, unless otherwise indicated, and should be interpreted as initial concentrations or maximums, as some Zn2+ ions bind with salivary proteins and some are absorbed into tissues.

    Each of the following reports was analyzed using published data, lozenge samples from the studies, manufacturers' formulas for the lozenges used in the studies, and replicated lozenges based upon the manufacturer's descriptions to determine ZIA, half-lives, and changes in duration. All data are supported by the original sources. Confirmation of the lozenge ingredients and manufacturing procedures can be obtained from the original cited sources.

    Every possible effort was made to report the findings of the researchers accurately, to discover exactly how lozenges were made, to discover how lozenges were actually used, and to discover the ingredients and their amounts present in the lozenges.

    Every possible effort was expended to assess accurately the differences in the reported results caused by variation in the procedures and actual chemistry of the lozenges used in clinical trials.

    4.A. Effects of Hydrated Zn2+ Ions on Duration of Common Colds

    Several published reports, which will be fully described later in this chapter, show the beneficial effects of positively charged hydrated Zn2+ ions on common cold severity and duration. Analysis of the reports shows zinc gluconate lozenges containing no other zinc-complexing agents reduce the severity and duration of common colds in a dose-dependent manner. The fraction of zinc initially released from zinc gluconate at 30 mMol as Zn2+ ion is about 30 percent at pH 7.4 in the absence of any other chelator (see Figure 1 in Chapter 1). The first study used unsweetened zinc gluconate tablets as lozenges. Tablets stimulated production of very little saliva and lasted about 30 minutes. Lozenges produced a high ZIA value and reduced colds by 7 days. The second study used fructose-based zinc gluconate lozenges. Sweetness stimulated production of more saliva. Lozenges dissolved more quickly, had a ZIA value slightly less than half the value of the first study lozenges, and proportionately reduced colds by 4.8 days. The third and fourth studies used low-dosage lozenges, had lower ZIA values, and were less effective on common colds.

    Chapter 4. A.1. - Original 1984 Eby Study

    During the fall cold season of 1981, George A. Eby, Donald R. Davis, and William W. Halcomb tested 660-mg zinc gluconate tablets used as throat lozenges containing 23 mg zinc (1.5 RDA) and no other zinc chelators or soluble ingredients. The Eby group found the zinc gluconate lozenges effective in shortening the average duration of natural common colds by 7 days in a double-blind clinical trial.(1) The two experimental groups in the study responded completely differently, and the effects of the lozenges were clear from the beginning. In the zinc-treated group 22 percent were well within 1 day, versus none in the placebo-treated group (P = 0.008, by exact binomial). The half-life (H) of zinc-treated colds was 2.7 days compared to 7.5 days for placebo-treated or untreated natural colds. This is to say, each 2.7 days, the number of patients remaining ill was reduced by one-half with zinc treatment; this result occurred at 7.5 days for placebo treatment. Average duration (H/ln 2) of zinc-treated colds was, therefore, 3.9 days, while placebo-treated colds averaged 10.8 days. On day 7, 86 percent of 37 zinc-treated patients were asymptomatic compared with only 46 percent of 28 placebo-treated patients (P = 0.0005). The entire article is presented here.

    The only ingredients in the 660-mg tablets were 175 mg zinc gluconate (23 mg zinc), dicalcium phosphate, microcrystalline cellulose, sodium starch glycolate, magnesium stearate, and FD & C yellow number 5 and blue number 1 (aluminum lake) coloring. With exception of the lake colors, all ingredients were essentially nonsoluble and nonreactive with zinc gluconate. Stability constant computations revealed about 60 percent of zinc was present as Zn2+ ion at salivary pH 5 to 5.5, and 30 percent of zinc was present as Zn2+ ion at physiologic pH 7.4 (see Figure 1 in Chapter 1). Although lake colors probably chelated some zinc, the amount appears to have been insignificant. The exact quantities of each ingredient except zinc gluconate are unknown, but one could theorize that amounts used were calculated to result in a slow dissolution rate. Tablets required about 30 minutes to dissolve in the mouth.

    Because lozenges were small, bland, hard tablets that dissolved slowly, lozenges stimulated production of very little (15 ml) intra-oral dissolution/expectorations of zinc-laden saliva. Salivary Zn2+ ion concentration was 7.4 mMol or less at pH 7.4. The pH of zinc-laden saliva was 5.5. The pH of similar concentrations of zinc gluconate in de-ionized water was 6.4. Lozenges produced moderately strong astringency in the mouth and considerable amounts of nonpalpable salivary protein precipitate. Lozenges were used every two hours while awake and totaled 9 doses/day. Lozenges had a ZIA value of 100.

    No patient complained of bitterness. Placebo lozenges contained calcium lactate as placebo, but were otherwise identical to zinc gluconate lozenges in respect to ingredients, size, shape, color, odor, and texture. The primary taste in both zinc gluconate and placebo lozenges was of dicalcium phosphate. Both had a dry, chalky, medicinal flavor. Neither zinc gluconate lozenges nor placebo lozenges were perceived by the patients or investigators as having an objectionable, bitter taste typical of zinc gluconate prepared with soluble sweeteners such as sucrose or dextrose.

    Neither the zinc gluconate tablets nor placebo tablets were designed for oral dissolution, and therefore no sweeteners or flavors were present.

    Patients

    All patients were recruited during the fall using local radio and television advertisements. People with early onset common colds were invited to join a clinical study intended to determine if zinc gluconate lozenges could shorten duration of common colds. All patients were both self diagnosed and diagnosed by the physician (William W. Halcomb, a general practice physician and allergist) to have uncomplicated common colds.

    Persons presenting with an allergy were not admitted to this study. Likewise, pregnant women and persons on immunosuppressive drugs were not admitted. Persons with known serious health disorders were also excluded.

    Informed consent was obtained in writing after explanation of the study. Patients filled out a printed health questionnaire and were instructed in the study protocol. Patients chose a randomly coded bottle containing either 75 zinc gluconate or 75 placebo lozenges in a double-blind manner.

    The following treatment instructions are the exact instructions given in the original 1984 clinical trial, and these instructions should be followed in all future clinical trials.

    Treatment Protocol

    At the first office visit, patients were instructed to dissolve tablets slowly as lozenges. Loading dose was two tablets (46 mg zinc), taken one after another. The double-strength loading dose was considered important to rapid recovery from symptoms, and everyone was instructed to be certain the double dose was taken. Emphasis was placed upon slowly dissolving lozenges in a manner intended to maximize the amount of zinc that could be absorbed into mucosal membranes of the mouth and throat.

    Adults and youths over 60 pounds were to dissolve one tablet every two hours while awake after the loading dose. Children under 60 pounds were to dissolve 1/2 tablet every two hours while awake. All were instructed to continue treatment every two hours while awake until 6 hours after the end of the last common cold symptom. All were instructed to avoid stress and include one or two treatments during the first day after cessation of symptoms as insurance against relapse.

    Experience with many common colds using zinc gluconate lozenge treatment during the 4 years immediately preceding the study also showed results could be improved if certain other steps were followed. Patients were told results might be improved if patients (a) slept after the first treatment and after other treatments when possible, (b) used a lozenge at bedtime (especially important as lymph circulation stops during sleep holding Zn2+ ions in tissues overnight), (c) took lozenges after meals and liquids (not before or on an empty stomach to avoid nausea), (d) avoided mouthwashes or alcohol, (e) avoided aspirin, antihistamines, decongestants, or other cold remedies, and (g) avoided smoking.

    Patients were instructed to eat soda crackers if nausea occurred. More recent research confirms these techniques to improve results, perhaps by helping to prevent removal of zinc from oral tissues as well as by preventing immunosuppression or complexation of Zn2+ ions by other drugs.

    Each patient was given a "treatment response form" in which they were to record severity of ten common cold symptoms each day for 7 days at the same time of day as their initial office visit. Symptoms studied were headache, fever, muscle pain, sneezing, nasal drainage, nasal obstruction, sore throat, scratchy throat, cough, hoarseness, and other. Common cold symptoms were scored as being either severe (3 points), moderate (2 points), minor (1 point), or absent (0 points). Space was provided to record side effects and other comments about treatment.

    Chi-square and t-test statistical tests were used except as noted. P values below 0.05 were considered significant.

    Results of 146-Patient Study

    Results of the study for those patients having been ill for only 3 days before enrollment have been published.(1) The paper was criticized on several counts. One criticism was only sixty-five patients out of 146 patients who enrolled were reported. This omission suggested bias, even though the main results for all reportable patients were mentioned in the report as: "After the 7-day experiment, 90 percent of the zinc-treated patients reported no cold symptoms, compared with only 49 percent of the placebo-treated patients (P << 0.0001)."

    Table 1. Characteristics of 80 patients

    ____________________________________________________________________________
    
    				    Zinc-treated	  Placebo-treated
    ___________________________________________________________________________	
    
    Total patients				41			39
    Male/female				20/21			22/17
    Age range				11-63			14-67
    Mean age + s.e.m.			34 + 2.0		37.5 + 2.3
    Smokers					9			9
    History of allergy			15			14
    History of over 4 colds/year		7			8
    Pretreatment use of zinc supplements	4			5
    Pretreatment use of vitamin C 		13			17
    Mean pre-enrollment duration
    	of colds + s.e.m. (days)	2.2 + 0.2		2.6 + 0.3
    Mean initial number of
    	symptoms + s.e.m.		5.4 + 0.3		6.3 + 0.4
    Mean initial total severity
    	score points + s.e.m.		9.5 + 0.7		10.3 + 0.7
    ___________________________________________________________________________
    

    The report was limited out of concern by the authors and journal editors for possible superimposed allergies and bacterial infections in colds of longer duration. Also, a main goal of the research was to study the effects of zinc gluconate lozenges on colds of short pre-treatment duration, not long duration. Short pre-treatment duration better assessed possible impact of Zn2+ ions on rhinoviruses which are believed to replicate immediately before onset of common cold symptoms and during the first day or two of symptoms. To encourage unbiased reporting of pre-treatment duration of common colds, all patients were accepted into the study regardless of how long their colds had lasted before initiation of treatment.

    The second and main criticism was the possibility of unblinding because of oral side effects and taste differences between zinc and placebo. To answer unblinding criticisms, subgroups of zinc-treated patients offering comments or complaints about taste, aftertaste, and oral side effects were compared with those not offering complaints. There were no differences in response to zinc treatment between the two subgroups. Taste problems associated with zinc gluconate in sucrose, dextrose, and sugar-alcohols are absent from zinc gluconate tablets having no other soluble ingredients.

    Of 146 volunteers originally enrolled in the study, colds had lasted 10 days or less in 83 of the zinc-treated patients, and in 63 of the placebo-treated patients. Of these, 108 returned response reports (64 zinc, 44 placebo) of which 80 contained sufficient data for full analysis (41 zinc, 39 placebo). Characteristics of these 80 patients are shown in Table 1 along with information about their colds. Analysis of these characteristics and a number of others indicated randomization procedure to have been successful in producing similar groups. Three measures of degree of illness indicated the placebo group to have had slightly more intense colds than the zinc group. One of these measures approached statistical significance (initial number of symptoms reported, t = 1.8, two-tailed P = 0.08), but this difference does not appear to have affected results.

    Duration of Cold Symptoms

    Table 2 shows numbers of patients who reported various common cold symptoms at different times. Each of the most common symptoms (nasal drainage, nasal obstruction, sore throat, scratchy throat and headache) was initially reported by 60 to 80 percent of patients, while the least common symptom (fever) was initially reported by about 30 percent of the patients. These observations are generally comparable to results of Gwaltney(2) for rhinovirus colds. Table 2 also contains our central findings on patients who reported presence of any one or more of 10 common cold symptoms at various times.

    Table 2. Numbers of patients reporting common cold symptoms at various times.

    ______________________________________________________________________
    
    Symptom      Treatment  Hour Hour Hour Day  Day	Day  Day  Day  Day  Day
    	       Group	 0    6	   12   1    2	 3    4	   5	6    7
    ______________________________________________________________________
    
    Headache     Zinc	 27   17   12    9   5	 4    0	   0    1    1
    Headache     Placebo	 23   19   17   13   7	 6    5	   3	3    5
    
    Fever	     Zinc     	 13   11    8    7   5	 2    0	   0	1    0
    Fever	     Placebo     12   10   10    8   6	 5    5	   4	2    3
    
    Muscle pain  Zinc        20   16   13   10   5	 3    0	   0	0    1
    Muscle pain  Placebo     17   15   14   12   8	 5    5    5	4    4
    
    Sneezing     Zinc        21   14   12    9   7	 6    2	   0	2    1
    Sneezing     Placebo     27   20   19   17  13	 9    8	   7	7    7
    
    Nasal 
      drainage   Zinc        31   26   24   23  20	17    8	   4	4    4
    Nasal 
      drainage   Placebo     32   30   32   32  28	25   23	  20   19   15
    
    Nasal obstr-
      uction     Zinc        24   23   20   18  16	11    6	   3	3    3
    Nasal obstr-
      uction     Placebo     32   30   29   30  27	22   17	  16   15   11
    
    Sore throat  Zinc        27   22   17   15   9	 5    1	   1    0    0
    Sore throat  Placebo     23   21   19   16  13	10    7	   6	5    4
    
    Scratchy 
      throat     Zinc        22   17   12   13   9	 5    1	   2	0    0
    Scratchy
      throat     Placebo     29   27   26   25  18	14   14	  11   11   10
    
    Cough	     Zinc        18   16   l3   12  10	 9    5	   4	4    3
    Cough	     Placebo     24   23   23   22  20	16   16	  11   11   11
    
    Hoarseness   Zinc        19   15   13   15   9	 6    1	   1	1    1
    Hoarseness   Placebo     25   20   18   20  14 	 9   10	   6    5    5
    ______________________________________________________________________
    
    Any symptom   Zinc       41   37   35   31  24	18   10    8	5    4
    Any symptom   Placebo    39   39   39   39  37	32   29	  27   26   20
    ______________________________________________________________________
    

    Duration of common colds was defined as presence of any one or more of these ten symptoms. Presence of any one or more common cold symptom is the main result of the study, and is also shown in Figure 3.

    The two experimental groups clearly responded differently, and the effects of zinc were apparent from the beginning. In the zinc group, sizable numbers of patients became completely asymptomatic rather quickly -- 15 percent within 12 hours and 25 percent by 24 hours -- whereas no placebo-treated patient was symptom-free within 24 hours (P < 0.02 at 12 hours, P < 0.001 at 24 hours, by exact binomial calculations).

    The plot for the zinc group is roughly an exponential decay with a half-life of about 2.2 days; this is to say, half of the remaining symptomatic patients became symptom free about every 2.2 days. In contrast, half of the placebo group required 7 days to become asymptomatic, in agreement with generally accepted durations for common colds. In our zinc-treated population, 90 percent were asymptomatic by day 7 compared with 51 percent of the placebo-treated population (P << 0.0001).

    The experiment was too short to measure fully average duration of cold symptoms, especially in the placebo group. Even if all symptoms remaining on day 7 had ended by day 8 for both groups (extremely unlikely), the effect of zinc lozenges on average duration would have been statistically highly significant (average duration would be 3.0 days in the zinc group and 5.9 days in the placebo group, P<< 0.0001). Improved estimates of average duration of these colds can, in this case, be based on average duration for an exponential decay curve (half-life/ln 2) and on half-lives. This method of extrapolation leads to average durations of 3.2 days and 10 days and to an estimated 7-day reduction in the average duration attributable to zinc gluconate lozenges.

    Examination of the ten individual symptoms reported in Table 2 shows each to have cleared more rapidly in the zinc group than in the placebo group. In some cases these differences are independently statistically significant after just 1 day (P<0.05 by exact binomial calculation for nasal drainage, and cough). Most persistent symptoms (nasal drainage, nasal obstruction, and cough) had half-lives of about 5 to 7 days in the placebo group, but only about 3 days in the zinc group. All other symptoms, including several pain-related symptoms (muscle pain, sore throat,scratchy throat, fever, headache), sneezing, and hoarseness seemed to disappear completely by the fourth day in nearly all zinc-treated patients. In placebo-treated patients, these symptoms did not improve after the third day during the week of the study. Only two patients reported recurrence of any symptoms after becoming symptom free. Both were in the zinc group. In one patient one mild symptom recurred 1 day after stopping treatment, but it disappeared again after 5 more lozenges. This patient confessed he had taken only about half of the recommended dosage throughout the experiment. The other patient was asymptomatic on day 2 but had a full-blown cold with six symptoms on day 3. She resumed treatment and was asymptomatic again by day 4 and thereafter. Although provision for listing other symptoms was made, only one person (in the zinc group) indicated another symptom: acute sinusitis which cleared in 3 days.

    Figure showing rapid decline in number of persons with colds given zinc compared to people given placebo

    Figure 3. Duration of common colds in ZIA 100 zinc gluconate- and placebo-treated groups.

    The possible effect on results of the difference between the two groups in their initial number of symptoms was evaluated. Several methods showed there was no appreciable effect. There was essentially no correlation between initial symptoms and duration of colds in either group (r = 0.1 zinc, -0.1 placebo). Likewise an analysis of covariance showed negligible interaction of these variables. As a final test, the effect of temporarily excluding from analysis 20 percent of placebo patients having the most initial symptoms and 20 percent of the zinc patients with fewest initial symptoms (thereby more than removing initial difference between groups) was calculated. There was still no change in half-lives and statistical trends previously given.

    Rates of recovery in various subgroups of patients were studied. The data suggest zinc may have benefited women more than men, perhaps because of size and weight differences or differences in oral mucosal membrane thicknesses, and non-smokers more than smokers (by 1-2 days average duration, P = 0.05 to 0.2 at several different times). Data similarly suggested in both the zinc- and placebo-treated groups younger patients recovered more quickly than older patients (by 2-3 days average duration), and patients who reported taking vitamin C supplements before the study recovered more quickly than those who did not (by 1 day average duration). These possible relationships are uncertain and require further study. No other characteristic was found to impact recovery in subgroups, including the presence or absence of complaints about taste or side effects.

    Diligent efforts to detect differences in responses to treatment between zinc-treated patients who recorded a complaint about oral side effects and zinc-treated patients who did not were performed. Plots of duration of cold data for both subgroups were identical, strongly suggesting taste was not a factor in responses of zinc-treated patients.

    In preliminary field trials in numerous participants before the formal clinical study, we frequently observed that when zinc treatment was started within 2 hours of onset of cold symptoms, the apparent colds usually would be aborted within 1 to 4 hours.

    The present study could not adequately test this observation because only two zinc-treated patients' colds had lasted 6 hours or less before enrollment. Although one patient became asymptomatic within 6 hours, the other patient's cold lasted 5 days.

    Severity of Cold Symptoms

    Table 3 shows average severity scores at various times for each of the 10 symptoms studied. For all symptoms, severity scores fell considerably faster in the zinc group than in the placebo group. Table 3 also shows average severity scores for all symptoms combined, and these are presented in Figure 4. Most persistent symptoms (nasal drainage, nasal obstruction and cough) were reduced in severity in the zinc group by about 30 to 40 percent during the first day, by about 60 percent by the fourth day, and by about 66 to 83 percent by the seventh day. All other symptoms, including pain-related symptoms (muscle pain, sore throat, scratchy throat, fever, and headache), sneezing, and hoarseness appeared to disappear completely by the fourth day in nearly all zinc-treated patients. In the placebo-treated patients, no symptom improved significantly after the fourth day. Severity of zinc-treated colds was one-half of placebo-treated colds on day 2.5. Severity of colds in the zinc-treated group was less than 12 percent of the severity of common colds in the placebo-treated group on the seventh day.

    Table 3. Average severity of 10 common cold symptoms at various times*

    ____________________________________________________________________________
    
    Symptom  Treated   Hour  Hour Hour  Day   Day   Day   Day   Day   Day   Day
    	Group  N     0     6   12    1     2     3     4     5     6     7    
    ____________________________________________________________________________
    
    Headache    Z  27 1.70  0.93  0.59  0.41  0.26  0.19  0.00  0.00  0.04  0.04
    Headache    P  23 1.48  1.22  1.09  1.00  0.48  0.39  0.35  0.26  0.26  0.39
    
    Fever	    Z  13 1.46  1.23  0.92  0.77  0.46	0.15  0.00  0.00  0.08	0.00
    Fever	    P  12 1.42  1.17  1.17  0.92  0.67	0.58  0.58  0.50  0.33	0.42
    
    Muscle pain Z  20 1.65  1.35  0.90  0.60  0.30	0.20  0.00  0.00  0.00	0.05
    Muscle pain P  17 1.41  1.18  1.18  0.94  0.65	0.47  0.47  0.47  0.41	0.41
    
    Sneezing    Z  21 1.43  0.90  0.67  0.62  0.48	0.43  0.14  0.00  0.14	0.05
    Sneezing    P  27 1.52  1.07  1.00  1.04  0.81	0.59  0.56  0.52  0.56	0.56
    
    Nasal 
      drainage  Z  31 1.87  1.23  1.10  1.10  0.97	0.77  0.45  0.23  0.23	0.16
    Nasal 
      drainage  P  32 1.94  1.56  1.59  1.66  1.47	1.28  1.13  1.00  0.97	0.84
    
    Nasal 
      obstruct  Z  24 1.83  1.50  1.29  1.13  0.92	0.67  0.38  0.25  0.25	0.17
    Nasal 
      obstruct  P  32 1.84  1.53  1.59  1.66  l.44	1.09  0.91  0.91  0.88	0.75
    
    Sore throat Z  27 1.78  1.33  1.11  0.89  0.56	0.30  0.07  0.04  0.00	0.00
    Sore throat P  23 1.70  1.30  1.22  l.22  0.91	0.61  0.43  0.39  0.30	0.26
    
    Scratchy 
      throat    Z  22 1.73  1.27  0.86  0.91  0.68	0.36  0.09  0.14  0.00	0.00
    Scratchy 
      throat    P  29 1.66  1.24  1.28  1.21  0.90	0.69  0.69  0.62  0.59	0.52
    
    Cough       Z  18 2.06  1.39  1.11  0.94  0.83	0.61  0.39  0.28  0.28	0.22
    Cough	    P  24 1.75  1.46  1.54  1.38  1.29	1.08  1.00  0.75  0.75	0.71
    
    Hoarseness  Z  19 1.84  1.16  0.89  0.95  0.58	0.37  0.05  0.05  0.05	0.05
    Hoarseness  P  25 1.40  1.16  1.04  1.04  0.68	0.56  0.52  0.44, 0.44	0.44
    ____________________________________________________________________________________________________________
    
    All symp.   Z 41  9.46  6.63  5.15  4.54  3.34	2.29  0.93  0.56  0.59	0.41
    All symp.   P 39 10.33  8.21  8.10  7.85  6.21	4.90  4.39  3.95  3.69	3.51
    ____________________________________________________________________________________________________________
    

    *Group sums of severity scores in points divided by number of patients N having symptom at start of treatment (severe = 3 points, moderate = 2 points, minor = 1 point, absent = 0 points).

    An initial abrupt decrease in reported severity occurred in both groups at hour 1 (not shown), perhaps partly because of changed circumstances and expectations following enrollment in the study. Then the two groups diverge convincingly at 12 hours and thereafter (P<0.01 to 0.001 through day 7). Whereas the zinc group recorded a 50 percent drop in severity scores in less than 1 day, the placebo group required 3 days for the same reduction. In the zinc group, total severity scores continued to fall rapidly and nearly exponentially from hour 6 through day 7, with a half-life of 1.5 days, compared to a half-life of 5 days in the placebo group after hour 6.

    Severity in zinc-treated colds diverged from severity of placebo-treated colds in the first day of treatment (Figure 4). They dropped to about 60 percent of placebo by day 1, and remained at about 20 percent of the severity of placebo-treated colds from day 4 through day 7. Standard error of mean (s.e.m.) did not exceed one point for placebo-treated colds at any time. The s.e.m. did not exceed one point for zinc-treated colds during the first 3 days and did not exceed one-half point from day 4 through day 7. In vitro, zinc has effects on prostaglandin metabolism.(3) Those effects may attribute to a feeling of well being and reduction in pain-related symptoms (muscle pain, sore throat, scratchy throat, fever, and headache) in common cold treatment.

    Side Effects and Complaints

    Space was provided on the response form to report side effects and other comments. Patients were told nausea, vomiting, and diarrhea were possible side effects. Large doses of zinc (350 mg zinc) have been used as an emetic. Table 4 shows all reported complaints, including reports from patients who dropped out. About 38 percent more of the zinc group than the placebo group reported some objection to treatment, primarily unpalatable taste, irritation of mouth tissues, and distortion of sense of taste. Nausea in a few patients was probably attributable to zinc, but this is not established by the present data (P = 0.3). Most of the complaints were mild and considered an acceptable part of treatment.

    Figure showing rapid decline in severity of colds of persons given zinc compared to people given placebo

    Figure 4. Average total severity of colds in ZIA 100 zinc gluconate and placebo-treated groups.

    On the other hand, most of the dropouts from the zinc group resulted from oral side effects including tablet grittiness. Reaction to zinc gluconate tablets was quite varied. A few patients had strong reactions to their taste while the majority of patients had no comment, accepting the bland, chalky taste as a reasonable and acceptable part of treatment. Some oral side effects are now primarily attributed to the nonsoluble formulation of lozenges. Unpalatable taste was a result of zinc gluconate and dicalcium phosphate. Irritation of mouth, tongue, and throat may also be caused by abrasive non-soluble tablet excipients. Three-fourths of all complaints were from women. Most side effects were accepted as a normal part of therapy by patients, and were considered a trade-off for a quick recovery. A complete listing of side effects and complaints is found in Table 4.






    Table 4. Side effects and complaints

    _________________________________________________________________________
    
    			          Zinc-treated        Placebo-treated
    _________________________________________________________________________
    
    Total number of patients 
    (includes dropouts)		    61 (100%)	         44 (100%)
    
    Number of patients reporting
    side effects and/or complaints	    33 (54%)	          7 (16%)
    
    Frequency of side effects 
    and/or complaints:
    
    Unpalatable taste		    10 (16%)	          2 (5%)
    Irritation of mouth, tongue 
    or throat			     9 (15%)	          1 (2%)
    Nausea or stomach distress	     9 (15%)	          4 (9%)
    Distortion of sense of taste         7 (11%)	          1 (2%)
    Transient mouth sores		     3 (5%)		  1 (2%)
    Vomiting			     2 (3%)		  0 (0%)
    Diarrhea			     1 (2%)		  1 (2%)
    ________________________________________________________________________
    

    Beneficial side effects reported by several patients and later verified with clinical and field experience(4) includes elimination or prevention of dysmenorrhea and bloating, and elimination and prevention of angina pectoris. Cramping and bloating were controlled in over 90 percent of women using 30-mg zinc doses 1 to 3 times per day as needed with meals several days each month. Women often commented they thought they would miss their period. Elimination of symptoms may reflect the strong effect of Zn2+ ions on prostaglandin metabolites in the uterus.(3) Complete control of angina pectoris with 60-mg zinc tablets 3 times a day occurs in one-half of patients in clinical practice,(4) which is in agreement with long-term zinc, lead, and cadmium environmental pollution studies reported in Poland involving thousands of people with angina and ischemia of effort (P < 0.001).(5) Coronary risk factors suggested by Chandra with much larger (300 mg zinc/day) doses(6) appear reversed at these lower doses (see Chapter 8).

    Drop-outs and Their Significance

    Among 64 patients in the zinc-treated group who returned response reports, 20 (31 percent) are considered dropouts because they stopped treatment and/or stopped recording symptoms before cessation of symptoms. Three other reports were rejected because of lack of usable data or because notation by patients that lozenges were swallowed rather than dissolved. Most zinc drop-outs (14 patients) occurred within 24 hours of starting treatment; 13 resulted from objections to treatment, 8 from side effects, and 5 from taste. Three blamed lack of benefit. At the time of dropping out, 13 zinc-treated patients had improved, two were worse, and five were unchanged or change was unknown based on severity scores.

    Drop-outs in the placebo group were rather different. Among 44 reports from placebo-treated patients, 15 (34 percent) dropped out (10 prematurely stopped treatment and five stopped recording symptoms). Seven stopped within 24 hours of starting treatment, and only one noted objection to the treatment as reason. Ten placebo-treated patients blamed lack of benefit. At the time of stopping, three placebo-treated patients' severity scores were improved, six were worse, and six were unchanged. Ten patients who stopped treatment but who recorded adequate symptom data were included in the placebo group analysis, because their stopping placebo "treatment" could not benefit their colds and because their omission might distort sampling of the group.

    The significant number of patients who dropped out makes uncertain how precisely results represent the entire population, but these drop-outs do not affect the fundamental finding. Assuming all drop-outs would have received no benefit (i.e., as placebo patients), there still would have been a significant benefit after 7 days: of zinc-treated patients, 16 of 64 asymptomatic versus placebo-treated patients 23 of 44 asymptomatic (P < 0.005). A similar, additional consideration of those patients who did not return reports still demonstrates a significant benefit of zinc lozenge treatment over placebo (P < 0.02). Only if we assume all zinc-treated drop-outs remained ill through day 7 (a horizontal response line), and placebo drop-outs healed at the same rate as other placebo recipients (half life = 7.5 days) do the differences become significant. In this extremely unrealistic case for an acute, self-limiting illness, 16 of 48 (33.3 percent) zinc recipients would still be ill as compared with 17 of 33 (51.5 percent) placebo recipients. (Chi square = 2.68, P > 0.10.)

    Zinc Ion Availability

    The tablets required about 20 minutes to dissolve in flowing water bath tests and about 30 minutes to dissolve in the mouth. This difference results from the differences in dynamics between the two methods. For example, patients often pigeon-hole lozenges in their cheeks with little dissolution occurring. Because lozenges were small, bland, hard tablets that dissolved slowly, little zinc-laden saliva was generated (15 ml) resulting in a high Zn2+ ion molar concentration (7.4 mMol) which was 74 times antirhinoviral concentration according to Korant and co-workers(7) and 148 times antirhinoviral concentration according to Merluzzi and co-workers(8) and Geist and co-workers.(9)

    Tablets had a ZIA value of 100 and reduced the average duration of all common cold symptoms by 7 days. ZIA 100 lozenges may produce antirhinoviral effects, judging from the very rapid initial response from these lozenges not seen in any study with lower ZIA values.

    Chapter 4.A.2. Great Britain Medical Research Council Common Cold Unit 1987 Study

    The British Medical Research Council (MRC) Common Cold Unit in Salisbury, England, tested zinc gluconate lozenges (23 mg zinc) against placebo in double-blinded human rhinovirus (HRV)-2 prophylaxis and therapeutic efficacy clinical trials.(10) The entire article is presented here.

    In the prophylaxis study, zinc reduced the total mean clinical score from 8.2 in the placebo group to 5.7. This reduction was statistically significant on the second day after virus challenge with HRV-2.

    In the therapeutic study, the mean clinical score for zinc-treated patients was consistently lower than for placebo-treated patients after day 1, reducing mean clinical score over the 6-day study from 41 in the placebo-treated group to 27.2 in the zinc-treated group. On each day of the study after day 1, mean nasal secretion weights from zinc-treated patients were less than half those of placebo-treated patients. On day 4 and afterward, nasal secretion weights in the zinc-treated group were nearly an order of magnitude lower than in the placebo-treated group. Results were statistically significant by several measurements at times during the study.

    The astringent lozenges were used every two hours while awake, totaling 9 doses/day. Lozenges were soluble, pleasant-tasting, 1-gram, wet-granulated fructose-Methocel(r)-based compressed tablets. No distinguishable difference in taste or appearance between zinc and placebo lozenges was observed. The zinc gluconate lozenges produced 22 grams of zinc-laden saliva and dissolved in 19 minutes. Salivary Zn2+ ion concentration was 5 mMol or less at pH 7.4. Salivary pH was 5.4. Reduction in duration was based upon the return to normal of symptoms in all zinc-treated patients on day 6 compared with the 10.8-day historic average duration of colds. Thus, treatment reduced average duration of colds by 4.8 days. Zinc lozenges had a ZIA value of 44.

    The zinc gluconate lozenges tested were made by RBS Pharma of Milan, Italy, (now part of Rôhne-Poulenc Pharma, Italia, S.P.A.). Professor Rinaldo Pellegrini, Medical-Scientific Director for RBS Pharma was the only researcher to visit with the original Texas group and follow advice concerning omitting zinc chelators from the lozenge formulation. RBS Pharma compounded zinc gluconate in fructose (a sugar), the only sweet tablet base that does not become bitter in solid state reactions with zinc gluconate.

    Lozenge Composition

    Lozenges contained 175 mg zinc gluconate (23 mg zinc) or placebo and weighted 1.00 gram each. Lozenges were one-half inch in diameter and 1/4 inch thick at the crown. Standard concave punches were used. Both were made using a binder with properties similar to high molecular weight hydroxypropyl methycellulose (Methocel(r) K4M) as viscosity of saliva was high, leaving the mouth with a moderately slimy feel. Both were tan in color. Saliva viscosity, tablet appearance, and very fine texture suggested the manufacturing process used to make these lozenges to have been wet granulation. Zinc gluconate carbonizes when mixed with carbohydrates at moderate temperature, requiring drying temperatures to be less than 50 C. to prevent most carbonization, consequently the lozenges had a light tan coloration.

    The original 1985 flavor was very sweetly flavored. Although lozenges were made in 1985, their taste in 1992 was still sweet with no evidence of the biting bitterness normally associated with lozenges made with dextrose, sucrose, or sugar-alcohols. Lozenges were moderately astringent and had a mild chalk-like undertaste identical to pure zinc gluconate powder. The first flavor-note was sweet during dissolution tests in 1985 and later in 1992. After flavor oils had evaporated from lozenges in 1992, lozenge flavor was less sweet, slightly chalky and bland without bitterness. After dissolving lozenges for about 15 minutes, a slight chalky taste of zinc gluconate along with increased astringency developed. Both zinc and placebo lozenges were quite astringent and caused an overnight dry mouth.

    The tablets showed no tendency to disintegrate at any time during dissolution from intact tablet to a tiny sliver. Oral dissolution times averaged 19 minutes. Lozenges produced an average of 22 ml of saliva during dissolution. ZIA calculations showed lozenges to have a ZIA value of 44, a modest value, because of increased salivation and more rapid dissolution rate.

    Research Design

    A lozenge tolerance and taste study first showed people were unable to distinguish between zinc and placebo lozenges. Two double-blind placebo controlled trials were then conducted at Harvard Hospital in Salisbury, England, to determine the prophylactic and therapeutic effects of zinc gluconate lozenges on human rhinovirus-2 (HRV-2) challenge.

    In the prophylactic study, a total of 57 volunteers received lozenges of either zinc gluconate (23 mg zinc) in 29 volunteers or matched placebo in 28 volunteers every 2 hours while awake during a period of 5 days. On the second day, volunteers were challenged with 102 tissue culture infecting dose (TCID50) of HRV-2, and were monitored daily for symptoms and signs of colds and laboratory evidence of infection.

    In the therapeutic study, 69 volunteers were inoculated with 102 TCID50 of HRV-2. Twelve developed cold symptoms and were randomly allocated to receive either zinc gluconate lozenges or placebo lozenges, with six receiving zinc lozenges and six receiving placebos every 2 hours while awake for 6 days. Lozenges were given from the time symptoms of a cold developed, and were continued throughout the duration of the trial. Volunteers were kept in quarantine for 48 hours before the start of the study as well as during the study.

    As day zero information for the therapeutic trial is missing from the MRC article, borrowed data from the prophylactic trial (Figure 1.a. of Al-Nakib) for day zero of the study was used to bring out significant details in the therapeutic trial results. According to David A. J. Tyrrell (MRC Common Cold Unit Director and study co-author) in 1993, combination of data from the separate studies is not absolutely legitimate (as one might expect), but combination is acceptable to Tyrrell as combination gives -- in his words, "...a rough idea of the sort of result one might obtain if the patients in the therapeutic study had been observed and the data analyzed as in the prophylactic study."(See original letter from D.A.J. Tyrrell here 11)

    Results of Prophylactic Trial

    Treatment in the prophylactic trial showed the response to zinc treatment to have been statistically significant on the day after viral challenge, with zinc reducing total clinical scores compared to placebo (8.2 vs. 5.7), mean nasal secretion weight, and virus excretion. Even though treatment was stopped on the third day after viral challenge, mean clinical scores for the zinc-treated group on the fourth, fifth, and sixth days remained lower than for the placebo-treated group -- by 30 percent on day 4, 38 percent on day five, and 20 percent on the sixth day even though mean nasal secretion weights had risen on day 5 by 20 percent.

    Results of Therapeutic Trial - Mean Clinical Scores

    Mean clinical score is estimated to be 0.1 for both groups on day zero. On the second day of the prophylactic trial, mean clinical score peaked at 8.5 and 12 points for zinc and placebo treatments respectively (see Figure 5). By day 6, mean clinical score for the zinc-treated group had returned to 0.6 which is six times pre-infection, while the score for the placebo-treated group returned only to 3.3 which is 33 times pre-infection. On day 6 the mean clinical score for zinc-treated patients was 20 percent of placebo-treated patients. Relative to placebo, by the sixth day zinc-treated patients had mean clinical scores essentially identical to pre-infection scores, showing colds were essentially absent in the zinc-treated group. All of the colds continued unabated in the placebo-treated group. Had the clinical trial lasted an additional day, the mean clinical score of zinc-treated patients might have reached zero. Similar benefit in the placebo-treated patients appears quite unlikely.

    Daily clinical scores of zinc and placebo treated groups

    Figure 5. Daily clinical score of ZIA 44 zinc gluconate- and placebo-treated groups. (Composite from Figures 1.a. and 2.a. of Al-Nakib, courtesy of Journal of Antimicrobial Chemotherapy).

    Zinc clearly reduced the mean daily clinical scorecompared with the placebo group score. Reduction in duration in the zinc-treated group compared with placebo treatment was statistically significant with only 6 patients per group on day 4 ( P < 0.01) and day 5 (P < 0.05) of treatment. Total mean clinical score (additive from day zero through day 6) was also reduced from 41 points in the placebo group to 27.2 in the zinc group.

    Results of Therapeutic Trial - Mean Daily Nasal Secretion Weights

    Zinc lozenges also reduced mean daily nasal secretion weight (grams) and total facial tissues used. These reductions were statistically significant from days 2 (P < 0.05) and 6 (P < 0.01) for nasal secretion weights and similarly significant on days 4 through 6 of medication for tissue counts when compared with placebo (Figure 6). Mean total nasal secretion weights were also significantly lower -- 22.0 grams in the zinc-treated group compared with 51.4 grams in the placebo group.

    In addition, zinc also significantly reduced the mean number of facial tissues used by volunteers compared to placebo on day 4 -- 1.42 versus 2.75 (P < 0.05), day 5 -- 0.25 versus 2.17 (P < 0.01) and day 6 -- 0.33 versus 1.67 (P < 0.05). Total mean tissue count for the 6-day period was thus reduced from 21.7 for those who received placebo to 14.3 for those who received zinc (P < 0.01).

    Daily nasal secretion weights of zinc and placebo treated patients

    Figure 6. Daily nasal secretion weights in grams for ZIA 43.9 zinc gluconate- and placebo-treated groups. (Composite from Figures 1.b. and 2.b. of Al-Nakib, courtesy of Journal of Antimicrobial Chemotherapy).

    On day 4, zinc-treated patients in the therapeutic trial had daily nasal secretion weights essentially the same as patients in the prophylaxis trial before viral inoculation, while placebo-treated patients had nasal secretion weights nearly 10 times higher than pre-infection. By day 6, all zinc-treated patients in the therapeutic trial had daily nasal secretion weights identical to nasal secretion weights of the patients in the prophylaxis trial before viral inoculation.

    MRC Conclusions

    The MRC Common Cold Unit concluded 1-gram zinc gluconate lozenges containing 23 mg zinc in a fructose and Methocel base used every 2 hours while awake consistently reduced both mean daily over-all symptoms and signs of disease as reflected in clinical scores and mean nasal secretion weights, the most objective measures of clinical response to treatment. The MRC Common Cold Unit indicated their findings warranted large field trials of zinc gluconate lozenges to extend and confirm zinc gluconate lozenge efficacy against natural common colds in the community.

    Generally, zinc gluconate in fructose-based lozenges was well tolerated despite the relatively large number of lozenges taken. Some volunteers commented that the taste of food was affected by lozenges, but no serious objections to either zinc or placebo lozenges were noted.

    No adverse changes in hematologic and biochemical indices were noted. Zinc-treated patients all showed a marked increase in urinary zinc excretion.

    Although viral excretion was about 20 percent less in the zinc-treated patients than in the placebo-treated patients in the prophylaxis trial during the first 4 days after viral challenge, the difference was not statistically significant, and the MRC indicated the mechanism of action responsible for significant benefit to cold suffers remained unknown.

    Duration of Common Colds and ZIA Calculation

    All placebo-treated patients had considerable symptoms remaining on day six, the end of the study. Given the data available it was not possible to know the absolute length of placebo-treated colds in this study. For zinc-treated patients, nasal drainage at days 4, 5, and 6 was estimated to be essentially the same as pre-infection. At day 6, mean clinical score and nasal secretion weights are essentially the same as pre-infection, judging from the pre-inoculation data from the prophylaxis trial.

    Consequently, duration of the zinc-treated common colds was 6 days, and average duration equals duration in this case. If the average duration of zinc-treated colds is compared with 10.8 days average duration (as has been historically found to be the case), a 4.8 day average reduction in common cold duration can be deduced from this experiment.

    Working backwards from average duration to half-life yields a theoretical half-life of 4.1 days for zinc-treated colds and 7.0 days for placebo-treated colds, which appears reasonably close to data shown in Figure 5.

    Zinc Ion Availability

    Calculation shows the ZIA value is 44. Lozenges dissolved in 19 minutes and produced 22 grams zinc-laden saliva. Salivary molar concentration of Zn2+ ion was 5 mMol, which was 50 times antirhinoviral concentration according to Korant and colleagues(7) and 100 times antirhinoviral concentration according to Merluzzi and colleagues,(8) and Geist and colleagues.(9)

    A ZIA value of about 50 and a Zn2+ ion concentration of about 5.0 appear to be minimal values for strong, but less than antirhinoviral, efficacy as colds did not disappear immediately upon initiation of treatment.

    Chapter 4.A.3. McNeil 11.5-mg Zinc Gluconate Lozenge Study

    In a study conducted by McNeil Consumer Products Company, low-dosage zinc gluconate lozenges reduced the duration of natural colds with effects occurring during the last 2 days of the 7-day double-blind trial.(12) Lozenges contained 11.5 mg zinc as zinc gluconate or sucrose octa-acetate, a bitter substance, in the placebo. The compressed lozenges weighed 1.56 grams and had a 15-minute dissolution time. Zinc gluconate lozenges produced 17.5 grams zinc-laden saliva and were slightly astringent. Zinc gluconate lozenges produced a salivary pH of 6.4. Salivary Zn2+ ion concentration was 3.3 mMol or less at pH 7.4.

    Confounding the analysis of ZIA, was the inclusion of many ingredients including sucrose, fructose, sorbitol, mannitol, mineral and acid stearates, Methocel(R), pineapple powder and three spray-dried flavors in both the zinc and placebo lozenges. Bitterness increases of one to three orders of magnitude over plain zinc gluconate that occurred in many zinc gluconate lozenges after aging is now known to be caused by solid-state reactions between zinc gluconate and all non-fructose carbohydrates. Extreme bitterness prevented nearly all patients from using the planned 20 lozenges per day; hence, the study could only report the effects of 10 or more lozenges per day, which was one-half the original planned dosage. Lozenges had a ZIA value of 25 and a 1.6 day average reduction in duration of zinc-treated colds. Reduction was determined from the half-lives (H) of the two groups by projecting the slopes of symptom duration curves and by dividing by ln 2 to arrive at average duration.

    According to the authors and the study coordinators, no one at McNeil Consumer Products knew the contents of the lozenges, other than the zinc lozenges contained 11.5-mg zinc from zinc gluconate. McNeil representative Eileen C. Helzner identified the manufacturer of the lozenges as General Nutrition Products, Inc., in Greenville, South Carolina. Lozenges were an over-the-counter health food store product that had been discontinued because of lozenge bitterness upon aging. No pre-formulation testing for Zn2+ ion was conducted.

    The McNeil study was conducted at three colleges and one family practice clinic January to May of 1986. All eligible patients had a clinical diagnosis of acute upper respiratory infection. Patients were given bottles of zinc or placebo lozenges to use to treat their colds at home. Zinc gluconate lozenges were half-strength at 11.5 mg zinc per lozenge. Patients were originally instructed to take an initial dose of 4 lozenges followed by 2 lozenges every two hours while awake in an effort to exactly replicate the original Eby protocol. Compliance was assessed through daily estimates by patients and by pill counts by investigators.

    These patients rated their symptoms on a scale of 0 to 3 with zero meaning no symptoms and 3 meaning severe symptoms. Patients were excluded from analysis if they took an insufficient dose (fewer than 10 lozenges per day) or if they did not take the lozenges for an adequate duration. Of 174 eligible patients with a clinical diagnosis of acute upper respiratory infection, 88 were assigned to receive placebo and 86 were assigned to receive zinc gluconate. Thirty-five (39.7 percent) of the placebo group and 29 (33.7 percent) of the zinc-treated group were excluded from analysis for reasons of insufficient dose (fewer than 10 lozenges) or duration of therapy.

    Results of Study

    Early response to zinc gluconate did not differ from placebo, as reflected in proportion of patients who continued to have symptoms (Figure 7). Response to zinc became directionally superior to placebo on days 6 and 7. About 41.4 percent of zinc-treated patients and 54 percent of placebo-treated patients remained ill on the seventh day of the study. Difference (12.6 percent) seen on day seven of the study was almost statistically significant (P = 0.09; 95% confidence level).

    Severity of illness was shown by the sum of individual symptom severity scores on any day as a proportion of baseline score. Patients using zinc gluconate lozenges had lower severity scores than those in the corresponding placebo group on day 4 (12 percent lower) through day 7 (40 percent lower) of treatment. The difference was statistically significant (P = 0.02).

    Late response to ZIA 25 lozenges

    Figure 7. Duration of common colds using bitter ZIA 25 zinc gluconate and placebo lozenges. (courtesy of Smith and Antimicrobial Agents & Chemotherapy).

    Examination of the McNeil data from Figure 7 shows from day 5 through 7, zinc-treated patients recovered at a faster rate than placebo-treated colds. Data and slope of curves show the half-life of zinc-treated colds to have been 6.5 days and the half-life of placebo-treated colds to have been 7.7 days by projection of the curves. Average duration of zinc-treated colds was calculated to be 9.4 days, and average duration of placebo-treated colds was calculated to be 11.1 days. Estimated reduction of half-life by zinc treatment was 1.2 days and estimated reduction in average duration for zinc treatment, 1.6 days.

    Adverse effects of medication included "dreadfully bitter" taste, nausea, altered taste, and dry mouth. Placebo was identical to the active lozenge except it contained sucrose octa-acetate, a bitter substance found to approximate the bitter taste of General Nutrition zinc gluconate lozenges used in the study. C. B. Goswick, a physician at Texas A & M University, and the study coordinator both reported that the study was a "bomb," or a "bust," as both zinc and placebo lozenges were so bitter that most patients refused to take the full dose, causing a high drop-out rate with little compliance in study dosage requirements. To save the study, physicians recommended patients use one lozenge, rather than two, every 2 wakeful hours.

    Cause of Lozenge Bitterness

    Lozenges became bitter as a result of reactions between zinc gluconate and dextrose, a reaction that occurs between zinc gluconate and all carbohydrate sweeteners except fructose. Additionally, stability constants of mannitol and sorbitol are four times higher than dextrose,(13) suggesting these sugar-alcohols not be used in lozenges intended to release Zn2+ ions. Absence of significant astringency and the presence of 12 identified chemicals plus four or more unidentified spray-dry chemicals resulted in a large number of possible reactions between zinc gluconate and other ingredients, all of which contributed to objectionable taste. These reactions rendered uncertain the availability of Zn2+ ions using this formulation. Little salivary protein precipitate was noted in expectorated saliva, suggesting near absence of Zn2+ ions.

    Lozenge Formulation

    The zinc gluconate lozenge formula tested by Smith and co-workers for McNeil Consumer Products Company was provided to the author by Bill Bannen of the Product Development Laboratory at General Nutrition Products, in Greenville, South Carolina, (Table 5). Lozenges were General Nutrition product code 1033, a 1985 over-the-counter heath food formulation, quickly manufactured and placed on the health food market without preformulation testing for Zn2+ ion bioavailability in response to the original article by Eby and co-workers.(14)

    The zinc gluconate and placebo lozenges contained 11.5 mg zinc gluconate or placebo. Lozenges weighed 1.560 grams, were 5/8 inch in diameter, and were 0.235 inch thick. The lozenges had a hardness of 12 KG and were flat faced with beveled edges. Dissolution rate was highly dependent upon tablet hardness.

    At the time of exact re-manufacture by this author in 1992, lozenges had a pleasant fruity taste, with moderate astringency and little taste of zinc gluconate. After aging for several months, the lozenges became increasingly bitter, to the point of extreme bitterness. Coupled with mucus-like texture of saliva from Methocel, the taste became really nasty and was much too bitter to use on an every 2-hour basis.

    Zinc Ion Availability

    Experimentation with exact copies of the McNeil lozenges, including tablet hardness and thickness, showed the zinc gluconate lozenges each produced 17.5 mg viscous zinc-laden saliva and required 15 minutes to dissolve, resulting in a ZIA value of 25.0 when used 10 times per day.

    Table 5. 11.5-mg zinc lozenge formulation-McNeil Consumer Products Company

    ___________________________________________________________________________
    
    Ingredient				               Quantity (mg)
    ___________________________________________________________________________
    
    zinc gluconate			  			 89.636
    compressible sucrose					627.368
    hydroxypropyl methyl cellulose (Methocel K4M)	         78.00
         --- granulate above with water----
    orange oil (2.5 fold) spray dried			  2.00
    lime flavor spray dried					  3.70
    natural cranberry flavor spray dried			 22.50	
    pineapple powder spray dried				 22.50
    fructose						118.554
    sorbitol - granular spray dried				200.00
    mannitol - granular					373.242
    magnesium stearate			    		  7.50
    stearic acid powder					 15.00
    
    Manufacturers of some McNeil lozenge components:
    
    Orange oil 2.5 fold  product 1606M - Borden
    Lime natural flavor  product 3823 (aura) - W. J. Flavors
    Natural Cranberry    product Trusil wonf # 5-9555 - Bush, Boake & Allen
    Pineapple powder     product flavor # 4737 - Borden
    ___________________________________________________________________________
    

    Had lozenges not been so objectionably bitter and had compliance been better, the McNeil zinc gluconate lozenges could have produced a ZIA of 50.0 using 20 doses per day, the recommended dosage. Low ZIA values resulted primarily from low zinc content and low usage rate. However, the bitter flavor stimulated saliva production, helping to lower lozenge ZIA value. Zn2+ ion salivary concentration was 3.3 mMol or less.

    Chapter 4.A.4. - Danish 4.5 mg Zinc Gluconate Lozenge Study

    During the winter of 1987-1988, 463 volunteers were enrolled in a zinc gluconate lozenge study at Bispebjerg Hospital in Copenhagen, Denmark.(15) Very low dose, non-astringent zinc gluconate lozenges were found ineffective compared to placebo in treating natural common colds in this double-blind study. Lozenges contained 4.5 mg zinc in a flavored, hard-boiled maltitol-syrup candy. Extreme bitterness caused the researchers to use the very low dosage. Maltitol is a liquid food ingredient consisting of 75 percent dry substance containing 72-73 percent hydrogenated disaccharides, a maximum of 8 percent D-sorbitol and with approximately 20 percent of the hydrogenated disaccharides having a degree of polymerization higher than 2.(16) Hard-boiled maltitol syrup based lozenges were manufactured by Alfred Benzon Company in Hvidovre.

    Volunteers were to use one lozenge each 1 to 1.5 hours (12 t/d), starting immediately after the first symptom of a common cold appeared. Similar 7.5-mg zinc lozenges produced a salivary average concentration of 1.4 to 4.4 mMol of zinc gluconate.

    Results of Study

    Durations of colds were evaluated by the Mantel-Cox test, with cessation of symptoms considered as the end-point. One hundred-thirty patients completed the study, with 69 patients receiving zinc and 61 receiving placebo. No statistically significant differences were found between the two groups with regard to age, sex, smoking, or severity of symptoms at the start of the study. Durations of common colds were virtually identical in zinc and placebo groups, with only minor fluctuations occurring. During the first four days, no differences in duration occurred. From day 5 through day 8, the placebo-treated group fared slightly better than the zinc-treated group.

    No improvement from ZIA 25 lozenges

    Figure 8. Effect of very low dosage ZIA 13.4 zinc gluconate and placebo lozenges (courtesy of Weismann, and Danish Medical Bulletin).

    No over-all improvement in severity of symptoms occurred. No statistically significant difference occurred in side effects between the groups, although three out of 61 receiving zinc lozenges noted an unpleasant taste. Lozenges were generally well tolerated by all patients. No significant change in serum zinc occurred with the use of 12 lozenges per day.

    Zinc Ion Availability

    ZIA values for these lozenges can only be estimated. All that is known is there was 4.5 mg of zinc as zinc gluconate in maltitol lozenges taken 12 times/day. If lozenges required 15 minutes to dissolve (a figure applicable to several commercial zinc lozenge products), and 17 ml of zinc-laden saliva was generated (also reasonable for lozenges), ZIA calculation results in a value of 13.4. Zn2+ ion salivary concentration was 1.5 mMol or less at 7.4 pH (see Figure 1 in Chapter 1). Zinc gluconate over-all salivary concentration was reported to be 4.4 to 5.0 mMol.

    As ZIA value was estimated to be only 13.4 percent as high as the original 1984 Eby lozenges, one can reasonably conclude low ZIA value was responsible for failure in this study. Flavor was considered acceptable and was probably not a consideration in lozenge failure, primarily because zinc content had been greatly lowered to arrive at a reasonably pleasant taste. For example, raising zinc to 7.5 mg resulted in an unacceptable taste in the maltitol tablet base.

    Chapter 4.B. - Effects of Strong Zinc Complexes on Duration of Common Colds

    Several studies have been conducted using zinc compounds that were either insoluble and released no Zn2+ ions, or were soluble but had a high stability constant and released essentially no ZnZn2+ ions at pH 7.4. No effect upon the duration or severity of common colds was noted using neutrally charged zinc compounds. These lozenges are representative of several health-food store products being marketed ostensibly for nutrition benefit in common colds, without benefit of a New Drug Application or any documentation.

    Chapter 4.B.1 Zinc Orotate Lozenges with Zinc Gluconate Nasal Spray Study

    Non-astringent zinc orotate lozenges manufactured by Makers of Kal, Inc., of Canoga Park, California, used in conjunction with saline "Ocean Nasal Spray" containing zinc gluconate were tested for efficacy against duration of common colds without any benefit being observed.(17) The test was a double-blind study conducted in a manner nearly identical to the author's zinc gluconate study also in 1981. Zinc lozenge dosage was 37 mg zinc per 3.6 gram lozenge. Lozenges were used every 3 hours with a quadruple initial loading dose. Lozenges also contained gum gaur (a powerful zinc sequestrant), cellulose, silica, and vegetable stearine. Zinc orotate lozenges were used as a substitute for zinc gluconate lozenges because zinc orotate did not have an objectionable taste in preliminary taste tests. Nasal spray contained 10 mMol zinc and was used aggressively every 15 to 30 minutes. Zinc gluconate had earlier appeared to have a strong effect as a decongestant when used as a nasal spray.

    Results of Study

    There were 77 volunteers (39 zinc, 38 placebo) in total. Twenty-eight zinc-treated patients and 27 placebo-treated patients returned report forms. Twenty-four of 28 zinc-treated patients and 23 of the placebo-treated patients had colds for 3 days or less before starting treatment. Of these patients, eight zinc-treated patients and six placebo-treated patients dropped out of the study. Two (12 percent) of the zinc-treated patients became asymptomatic on the first day, but no placebo-treated patients became well on the first day. No statistical significance between the differences between groups after one day (P = 0.23, exact binomial) was observed (see Figure 9). After the first day of study, no difference in rate of recovery between the two groups throughout the remainder of the study occurred, and plots for the two groups have essentially the same slope and are parallel. No further evidence of reduction in duration for the zinc group outside of the two patients who became asymptomatic on the first day occurred. By the end of the 7-day study, statistical significance of difference (P = 0.57, by chi square) was even less than at day 1.

    No antihistaminic effects were observed which appears contrary to in vitro findings of Harisch and Kretshmer for zinc orotate,(18) but may not actually be contrary, in as much as zinc orotate is highly insoluble at pH 7.4.

    Zinc Ion Availability

    The failure of zinc orotate lozenges appears to be attributable to the choice of zinc orotate. Zinc orotate is an insoluble compound of zinc at oral pH having a stability constant of log K1 = 6.42 at 25°C.(19) Consequently, zinc orotate releases no Zn2+ ions at oral or tissue pH. Lozenges were also insoluble to a significant extent. Although most dissolved in 40 minutes, complete dissolution took more than 3 hours for some patients. Lozenges were not particularly pleasant to use, because of the absence of a flavored, sweet carrier and the long time required for dissolution. No salivary protein precipitate in expectorated saliva was detected, directly suggesting absence of Zn2+ ions. Saliva generation averaged 18 ml. The average pH of intra-oral dissolution/expectorations was 7.0. Compliance seemed adequate.

    Zinc gluconate nasal spray failed because nasal sprays are quickly removed from locus of infection by mucous secretions as shown by Aoki.(20) Additionally, the out-flow of electrons from the mouth-to-nose BCEC repels Zn2+ ions from the surface of nasal tissues. 2001 ADDENDUM: Another possible explanation for failure of zinc gluconate nasal sprays in this experiment concerns the role of free orotic acid. Metal complexes often have the ligand in excess. In this experiment, orotic acid in the throat could have bound all Zn2+ ions released from the zinc gluconate nasal spray upon passage of the zinc gluconate into the throat.

    No effect from zinc orotate lozenges and zinc gluconate nasal sprays

    Figure 9. Effect of ZIA 0 zinc orotate and placebo lozenges and zinc gluconate nasal spray.

    Stronger nasal sprays could not be used as they caused intense, long lasting nasal pain. Patients reported zinc nasal spray was helpful as a short-lived decongestant. Perhaps this action is similar to decongestant action produced by various zinc nasal sprays used commercially from 1900 to 1966 in Europe, Australia and the United States, and as recently demonstrated by Derek Bryce-Smith with zinc sulfate (see Chapters 2 and 3). Because no Zn2+ ions were released from lozenges at pH 7.4, ZIA was 0.

    Chapter 4.B.2. - Zinc Aspartate Lozenge Study

    In his 1987 book Cold Cures, Michael Castleman popularized "Cold Season Plus" zinc aspartate lozenges by Quantum Research in Eugene, Oregon.(21) Those 1.5-gram zinc aspartate lozenges were tested for efficacy against an identical placebo against duration of common colds without any benefit being observed.(22) The double-blind clinical trial was comprised of University of Minnesota students having had common cold symptoms 3 days or less before enrollment in the study. The trial was conducted for 5 days with a telephone call or clinic visit on day 3 and a physician evaluation on the sixth or seventh day. Zinc lozenges contained 24 mg of zinc from zinc aspartate and were given every 2 hours while awake (9 lozenges/day). Persons believed to have complicated viral upper respiratory infections were excluded. Of 100 initial participants, 49 met criteria of having at least 4 out of 10 symptoms that had potential of improving by two points on a subjective evaluation by the patient.

    Results of Study

    Of the 49, 24 were judged to have improved. Of these 24, 11 (46 percent) received zinc aspartate lozenges and 13 (54 percent) received placebo. Of 25 patients judged as having not improved on at least four criteria, 16 (42 percent) received zinc aspartate and 22 (58 percent) received placebo.

    Using less stringent criteria, based only on investigators' impression of improvement from patient report forms, 25 additional patients were evaluated. Of these 25, 15 (60 percent) judged improved received zinc, and 40 percent did not.

    If these 25 and the 24 judged by stricter criteria are combined, 26 (53 percent) who received zinc lozenges were judged improved, and 23 (47 percent) receiving placebo were judged improved.

    See original study report from the University of Minnesota here.

    Estimate of ZIA 0 zinc orotate lozenges

    Figure 10. Effect of ZIA 0 zinc aspartate and placebo lozenges.

    No statistically significant differences between the groups were observed. Compliance to protocol was good, primarily because taste of the lozenges was pleasant.

    Zinc Ion Availability

    Greatly confounding this analysis, was the inclusion of 150 mg calcium ascorbate, 100 mg bee propolis, 25 mg slippery elm, 1000 IU vitamin A palmitate, 2 sugars, 2 stearates, Duratex, and 3 spray-dried flavor oils to both the zinc aspartate and placebo lozenges.(23) Failure of the study was attributed primarily to the use of zinc aspartate, a pleasant-tasting, non-astringent zinc compound having a first stability constant near log K1 = 5.9 at 37°C.(24) The conditional first stability constant at pH 6.8 is log K1 = 2.9 because of the protonated ammonium group.(25)

    Berthon and Germonneau found in vitro that zinc aspartate concentration needed to be raised 1000 times over its normal levels to be more efficient than Zn2+ ion alone to favor zinc-mediated histamine diffusion into tissues.(24)

    No salivary protein precipitate in expectorated saliva (18 ml saliva) was observed, suggesting the absence of Zn2+ ions. The average pH of zinc-laden saliva was 7.0. Oral dissolution time was 14 minutes. Failure of the study is primarily attributed to the use of zinc aspartate with its high molecular stability.

    Of the many possible detrimental solid-state reactions between zinc aspartate and lozenge additives, reactions with calcium ascorbate is possible. Zinc ascorbate samples we tested were essentially insoluble. Stability constant data show essentially no Zn2+ ions were present. ZIA was essentially zero.

    Chapter 4.C. - Effects of Strong Complexes with Ligand In Excess On Duration of Common Colds

    Three studies reported the effects of zinc complexes with strong ligands present in molar excess relative to zinc. Bristol Myers Products sponsored a study in which extramolar citric acid was used to flavor-mask zinc gluconate, resulting in approximately 1-day increase in common cold duration. An Australian study used several strong zinc chelators to provide an effervescent effect, resulting in severe worsening of symptoms and substantial lengthening of common cold duration. A study using zinc gluconate with glycine produced anomalous positive results.

    Chapter 4.C.1. - Citric Acid Flavor Masked Zinc Gluconate Lozenge Study

    Hard-boiled 4.5 gram sugar and corn syrup lozenges designed by the Bristol-Myers Company containing 175 mg zinc gluconate (23 mg zinc), 90 mg citric acid as flavor-mask, and lemon flavoring(25) were supplied for testing against placebo in two double-blind clinical trials. One trial was conducted by B. M. Farr and co-workers (32 patients) and the other by J. M. Gwaltney and co-workers (23 patients). No efficacy against HRV-13 and 39 colds was observed.(26) Lozenges had a mild pseudo-astringency. Citric acid was present at 1.33 molar ratio to zinc.(25)

    Working in conjunction with the Farr and Gwaltney led studies, Geist and co-workers found little antirhinoviral activity at non-cytotoxic concentrations below 0.03 mMol for either HRV-2 or HRV-39 in vitro -- as determined by cell rounding,(9) in actuality a harmless astringent effect.

    Korant reported cell rounding was not an indication of zinc cytotoxicity, and effects noted by Geist and separately by Merluzzi could be induced by many non-cytotoxic agents including a slight change in carbon dioxide concentration and changes to culture medium.(27)

    Zinc Ion Availability in the Zinc Gluconate and Citric Acid System

    R. Bruce Martin claimed Zn2+ ion concentration to have been 100 percent in saliva -- at pH 2.3, although no evidence to support the salivary pH hypothesis was presented.(25) The hypothesis that pH of saliva produced by an intra-oral dissolution/expectoration of a zinc gluconate with citric acid lozenge would be 2.3 from the acidity of citric acid and lack of buffering by saliva, with consequent 100 percent zinc ion availability(25) can be readily disproved by direct observation. Martin's hypothesis appears to be derived from the observation that the pH of 90 mg citric acid, without zinc or candy lozenge ingredients, in 30 to 35 ml distilled water (roughly equivalent to the amount of saliva generated using such lozenges) is pH 2.3.

    NOTE: Upon the retirement of R. Bruce Martin in 1994, he admitted in a letter dated May 9, 1994, that his report was faulty. He wrote, "I very much regret being forced into this theoretical calculation, and have wished for some time that I had not succumbed."

    In tests by the present author and others, lozenges chemically identical to those used in this report were subjected to analysis. When dissolved in 30 ml distilled water, the lozenges produced a pH of 3.2. Six unrelated individuals dissolved 12 replicated lozenges and expectorated all saliva flow. Average saliva volume was 35 milliliters. Lozenges required 15 minutes to dissolve. Average pH of 12 intra-oral dissolution/expectorations was 4.35 + 0.08,(28) a value at which little free Zn2+ ions exist, as shown in Figures 11 and 12 below.(25,29) No astringency or salivary protein precipitate in expectorated saliva was noted, further suggesting absence of Zn2+ ions.

    Even with five times the amount of citric acid used in the no-effect lozenges in otherwise identical lozenges, a salivary pH of 2.3 was not possible. The augmented formulation produced a pH of 2.9 in saliva but these lozenges caused significant oral pain and were offensively acidic and bitter in taste.

    The first stability constant of zinc citrate is log K1 = 4.7 at 37°C.(25,29,30-32) At the salivary pH of zinc gluconate-citrate and higher, the amount of Zn2+ ion is considerably less than from zinc gluconate. At physiological pH 7.4 there are no Zn2+ ions, and several negatively charged species predominate (see figures 11 and 12 below).(25,29)

    The only physiologically relevant pH is 7.4, as all others are quickly buffered to pH 7.4 in blood, lymph and tissue.(33,34) Negatively charged zinc complexes are repelled from cell surfaces, because cell surfaces are always electronegative,(35) and they have no theoretical or reported antirhinoviral, astringency, interferon-inducing, or cell plasma membrane stabilizing function.

    From each perspective (stability constants, and zinc ion availability), the experimental lozenges tested by Farr and co-workers, and Gwaltney and co-workers(26) released no zinc ions at physiologic pH.

    Mole fraction zinc with 1.3 mole citric acidFigure 11. Mole fraction Zn2+ species versus pH for solution with Zn2+ and excess citric acid (H3L). At any pH, the curves sum to unity. Curves were constructed from the stability-constant logarithms in parentheses after each reaction: Zn2++HL2-<=>ZnLH (3.0), Zn2++L3-<=>ZnL- (4.8), and ZnL-+L3-<=>ZnL-24- (1.7). Except for the ratio of the last two complexes, the general shapes of the curves are independent of the specific concentrations of 18 mMol Zn2+ and 23 mMol citric acid. Successive pKa values for citric acid deprotonations are pK1=3.0, pK2=4.4, and pK3=5.8. Not included in the analysis is a small amount of ZnLH2+ of low stability likely to form near pH 3. Figure courtesy of B.D. Martin and Antimicrobial Agents and Chemotherapy.(24)

    Speciation for zinc citrate Figure 12. Mole fraction for equimolar zinc and citric acid at 10 mMol. 1=Zn2+, 2=ZnL-, 3=ZnLH0, 4=ZnL24-, 5=Zn2L2(OH)2 Figure courtesy of Guy Berthon and JCS-Dalton.(29)

    Results of Study

    Clinical efficacy of lozenges containing 23 mg zinc from zinc gluconate chelated by extramolar citric acid was assessed in experimentally induced rhinovirus infection in two randomized controlled trials in susceptible adult volunteers.(26) In trial 1, lozenges containing either zinc gluconate (23 mg elemental zinc) chelated with citric acid or lozenges containing a placebo were given 36 hours after nasal inoculation of rhinovirus type 39. Lozenges were administered eight times per day for 5 days. All volunteers had early cold symptoms at the time treatment was begun. In trial 2, the same lozenge regimen was used beginning 2 hours after nasal inoculation with rhinovirus type 13 and was continued for 7 days.

    Estimate of effect of ZIA -11 lozenges Figure 13. Estimated effect of ZIA -11 zinc gluconate-citrate and placebo lozenges.

    Therapy with zinc gluconate chelated by extra molar citric acid did not reduce severity or duration of cold symptoms or frequency or duration of viral shedding in either trial and appeared to increase severity of common cold symptoms on day 7 (see Figure 13). A breakdown of symptom scores in both studies showed a statistically significant difference in symptom severity with recipients of citric acid-chelated zinc having more severe symptoms than placebo recipients on day 7. Recipients of citric acid-chelated zinc showed trends to higher mucus weight and a greater number of facial tissues used, but neither trend was statistically significant. During the studies, these patients had a 17 percent higher total symptom score, 15 percent higher mucus weight, and used 58 percent more paper tissues than placebo-treated patients.(26)

    Considering the day 7 data, zinc gluconate with extramolar citric acid appears to have increased the duration of common colds by approximately 1 day. Placebos also contained citric acid, lemon oil, and a bitter substance, denatonium benzoate. Zinc and placebo lozenges did not have identical tastes, or even similar tastes, but patients had statistically similar perceptions of activity of placebo and zinc lozenges.(36)

    Zinc Ion Availability

    The results of the clinical trials of Farr and co-workers, and Gwaltney and co-workers(26) do not represent the effect of Zn2+ ions in treatment of common colds. Negatively charged zinc citrate species (pseudo-astringents) in this study increased duration of common colds by approximately 1 day. The best estimate for the ZIA value of the citric acid-chelated zinc gluconate lozenges is negative 11, using linear ZIA relationships (See Chapter 5, Figure 19 equation) to project the value from an estimated 1-day increase in the duration of common colds.

    Chapter 4.C.2. - Australian 10-mg Zinc Acetate Effervescent Lozenge Study

    Effervescent lozenges containing 10 mg of zinc from zinc acetate used an average of 6 times per day were evaluated as a treatment of natural upper respiratory infections in a double-blind randomized trial in Australia by Douglas and co-workers.(37) Strong effervescence was produced by reacting tartaric acid and sodium bicarbonate, and the lozenge base was mannitol(38) as shown in Figure 15. Exact amounts of effervescence-inducing chemicals were not stated, although the chemicals caused "considerable fizzing in the mouth during their dissolution over a period of 10 minutes."(37) Various formulations for effervescent pharmaceutical preparations are available.(39) Several formulas use food acids and sodium bicarbonate to produce effervescence (see Table 6).

    Replicated lozenges were made using tartaric acid and sodium bicarbonate using the most likely 50:50 molar ratio of agents. The amount of tartaric acid and sodium bicarbonate was incrementally raised in 4-gram mannitol lozenges containing 10 mg zinc from zinc acetate. Lozenges containing 200 mg tartaric acid and 200 mg sodium bicarbonate lasted about 10 minutes, were only slightly effervescent, and produced 44 ml saliva having a pH of 4.6. At the 600 to 800 mg level, pH was 4.0, and the compositions were much too sharply acidic in taste to be acceptable. Most likely amounts were about 300 mg each for proper balance of effervescence and flavor in 4-gram lozenges. These amounts are substantially in molar excess relative to zinc. These pseudo-astringent, acidic tasting lozenges produced a salivary pH of 4.1.

    Table 6. Examples of citric acid-sodium bicarbonate in effervescent formulations from Mohrle.(39)

    _______________________________________________________________________

    Product		Citric Acid (g)  Sodium	  	  Product Weight (g)
    				 Bicarbonate (g)  
    _______________________________________________________________________
    
    antacid		 1.180   	  0.875			3.100
    antacid-
    analgesics	 1.060		  1.700			3.250
    flavored 
    beverage	 1.300		  0.815			2.230
    decongestant	 0.650		  0.550			1.330
    denture cleanser 0.575		  0.800			3.354
    _______________________________________________________________________
    
    average		0.953 (36%)	  0.948 (36%)		2.654 (100%)
    _______________________________________________________________________
    

    Results of Study

    Of 70 treatment courses used by 55 individuals in 34 families, 63 (33 zinc and 30 placebo) could be evaluated, in that they used medication at least four times daily for at least 3 days (average utilization of 6 lozenges daily for 5.4 days). Effervescent lozenges required 10 minutes to dissolve. Placebo blinding was shown adequate by statistical analysis. Whereas 60 percent of the placebo-treated colds lasted 7 days or less, only 42 percent of the zinc-treated colds did so, and 24 percent of the zinc-treated colds versus 13 percent of the placebo-treated colds lasted more than 12 days. One zinc-treated cold lasted 53 days.

    Mean number of days of respiratory nasal and cough symptoms were appreciably higher for effervescent tartarate-bicarbonate chelated zinc lozenge treatment compared to placebo treatment. Mean severity point score was higher for nasal and cough symptoms. The observed duration, as opposed to the calculated duration of colds, in the zinc-treated group averaged 12.1 days versus 7.7 days in placebo-treated group.(37) No salivary protein precipitate in zinc-laden saliva was noted, suggesting Zn2+ ions were absent. The amount of zinc-laden saliva generated was high at 44 ml per lozenge.

    The pH of tartaric acid in distilled water at the above concentration was 2.0. Zinc acetate totally dissociates in solution releasing 100 percent Zn2+ ion.(40) Tartaric acid was present in considerable excess, and it has a first stability constant for zinc of log K1 = 2.2.(41) Negatively charged zinc tartarate complexes are relatively stable, and few solution Zn2+ ions are available at physiologic pH 7.4.

    Estimated effect of ZIA -54 lozenges Figure 14. Estimated effect of ZIA -55 zinc acetate-tartarate- carbonate lozenges and placebo.

    Zinc acetate vigorously reacts with sodium bicarbonate, producing insoluble zinc carbonate precipitate, eliminating all Zn2+ ions, and leaving neutral and negatively charged zinc species.

    Zinc Ion Availability

    The ZIA value for tartarate and carbonate complexed zinc acetate lozenges is estimated to be negative 55 from linear ZIA relationships found in the Figure 19 equation to project the value from the 4.4 day increase in duration, and because negative zinc species are present.

    The finding of sharp increases in duration of colds using zinc complexes with excesses of these ligands is important to common cold research, and perhaps virology in general, and needs careful consideration and explanation.

    Letter from Faulding Corp. to R.M. Douglas showing procedures and methods for producing effervescent zinc lozenges

    Figure 15. Letter from R. J. E. Williams showing procedure and method for producing effervescence in zinc acetate lozenges.

    A suggestion that zinc chelators in lozenges bound endogenous zinc from oral and nasal tissues worsening common colds does not appear to be supported, as a similar lengthening by the placebos did not occur. However, negatively charged zinc species would bind endogenous zinc worsening colds in a linear dose-response manner.




    Chapter 4.C.3. - Zinc Gluconate-Glycine (1:10-mole) Lozenge Study

    In a 1992 double-blind, clinical study involving 87 patients by Godfrey and co-workers at Dartmouth College, zinc gluconate with glycine in 10 molar excess as flavor-mask in 4.5 gram sucrose-corn syrup hard boiled candy lozenges and identically astringent and flavored tannic acid placebos were both reported to have late efficacy against natural common colds.(42)

    However, the reported reductions in "average duration of colds" appear in actuality reductions in half-lives. Therefore, the half-life of zinc gluconate-glycine (ZGG)-treated colds, not the average duration (see Figure 2 and explanation in Chapter 3), was 1.27 days shorter (4.86 days) than placebo-treated colds (6.13 days) (t = 2.01, P < 0.05) in patients having colds for an average of 1.34 days before starting treatment. Ordinarily, the half-life for untreated or placebo-treated colds is considered to be 7 days. After the fourth day of treatment, patients using ZGG became symptom-free somewhat faster than volunteers using placebo. Results were reported to be significantly different by day 6 (P = 0.05).

    The most frequent symptom in both groups after 7 days of treatment was nasal drainage and nasal congestion. About 13 percent of the ZGG-treated group and about 34 percent of the placebo-treated group still had nasal symptoms after 7 days of treatment. From the half-life data above and Figure 1 of Godfrey and co-workers, it is possible to estimate the over-all effect of ZGG versus placebo on common colds in the whole study group (see Figure 16).

    Results seemed better with initiation of treatment of colds starting within 24 hours of the onset of the first symptom (see Figure 17). Severity of symptoms remaining on the seventh day for the sub-group of ZGG-treated patients having been ill for less than 1 day before starting treatment was also less than for the ZGG-treated sub-group having been ill for 2 days prior to starting treatment.

    Estimated effect of zinc gluconate-glycine (10 mole) versus placebo Figure 16. Estimated effect of zinc gluconate-glycine and placebo on duration of colds.

    The conclusion by Godfrey and co-workers that ZGG lozenge treatment shortened the average duration of cold by 43 percent appears erroneous. Their error results from misinterpreting half-lives of colds (usually 7 days), as the "average durations" of colds (usually about 10 to 11 days), which is an entirely different matter. An accurate assessment of the effect of ZGG lozenges on colds must take these major mathematical and conceptual differences into account.

    Effect of pretreatment for cold durationFigure 17. Effect of pretreatment cold duration for zinc gluconate-glycine treated sub-groups. (courtesy of Journal of International Medical Research).

    If the assessment of Godfrey and co-workers that colds first treated on their first day have a "total average duration" (in actuality a half-life) of 5.3 days, the half-life must be compared with the historical 7 day half-life of colds, not the 9.2 day average duration figure used in the Godfrey and co-workers report. Therefore, the reduction in half-live was only 1.7 days. If the half-life is divided by the natural log of 2 to give the average reduction in duration of exponentially decaying colds, the result is 2.5 days. However, this method of analysis is inaccurate for these non-exponential decay curves.

    The most accurate conclusions are one-half of the ZGG-treated colds ended 1.2 to 1.7 days before normal, and ZGG-treated patients fared better with essentially all colds being absent after seven days of treatment with ZGG when treatment was started on the first day of their colds.

    Zinc gluconate-glycine lozenges contained 23.7 mg zinc and 10 molar equivalents of glycine relative to zinc. Average zinc-laden salivary volume was 26.3 ml.(43) Lozenges were used every 2 hours while awake. Total zinc concentration was 14 mMol. Lozenges dissolved in 15 minutes.

    Zinc Speciation in the Zinc Gluconate-Glycine System

    The stability constants for zinc glycinate complexes are relatively high; for example, log K1 = 4.8 at 37°C.(44) With a 10-mole excess of glycine at the published salivary pH of 5.0, available Zn2+ ion concentration is 20 percent, but it falls rapidly to zero at pH 6.4; and only neutrally and negatively charged zinc glycinate and hydroxide species exist at physiological pH 7.4 and above as shown in Figure 18.

    NOTE: Learn about the meaning of "stability constants" here.

    Zinc gluconate-glycine Figure 18. Concentration of Zn2+, positively charged zinc gluconate (ZnL+), and various zinc glycinate and zinc hydroxide species in the zinc gluconate - glycinate system. Zinc and gluconate are present at 30 mMol and glycine is present at 300 mMol concentration. Distribution of zinc ionic species is courtesy of Guy Berthon, INSERM U 305, CNRS, Toulouse, France, 1992.



    Glycine replaces gluconate in solid state reactions during heated premixing of zinc gluconate and glycine powders and at elevated candy-making temperature, as well as in solutions. According to Berthon, only neutrally and negatively charged zinc glycinate species and excess glycine exist in solution at pH 7.4. Yet, Zarembo and co-workers believe zinc was 90 to 93 percent Zn2+ ion at pH 5.08 because of a previously unknown "catalytic action of saliva."(42,43) However, zinc gluconate with only 60 percent Zn2+ ion content (see Figure 1) added to hard-boiled candy stock at candy-making temperature and pH 5 severely caramelizes and quickly becomes offensively malodorous without added glycine or other strong chelator such as citric acid or acacia.

    Effects of Astringency

    Because Zn2+ ions, ZGG, and tannic acid are each astringent in saliva, late-occurring efficacy noticed in the zinc gluconate-glycine report for ZGG lozenges is most likely attributable to astringency. The action appears not from antirhinoviral action of Zn2+ ions at physiologic pH 7.4, as no Zn2+ ions are available according to Berthon (see Figure 18).

    Any possible Zn2+ ion action on rhinoviruses should occur during the first few days of a cold when rhinoviruses are present, yet no reduction in duration of colds was noted in this study during those early days. In fact, the frequencies of nasal symptoms were the least affected by ZGG lozenges. Effects on individual symptoms during the early phase also were likely to have been caused by astringency, and not Zn2+ ions. Late activity in a cold -- when viruses are essentially absent -- suggests the effect on duration is most likely caused by local astringency, a drying action. This action most likely would not include significant prevention of release of histamine from mast cells considering molecular stabilities.

    The suggestion by Godfrey and co-workers that the placebo was active seems implausible, and may not be supported by facts since the half-life of placebo-treated colds was 6.13 days which is essentially the same as the historical half-life of untreated common colds at 7 days, particularly when one adds the pre-treatment day.

    Zinc Ion Availability

    In this anomaly from the ZIA - day reduction trend, ZIA is unquestionably negative from lack of Zn2+ ions, the presence of neutrally (85%) and negatively (15%) charged zinc glycine species, and glycine in excess at pH 7.4. However, no ZIA data-point can be determined as the results do not fall into the quadrant used to estimate ZIA values for other lozenges having negative ZIA values. This anomaly results in a horizontal line to the left of the origin at a positive 1.27 days.




    Chapter 4.D. - Summary and Comments

    If zinc lozenges are to be useful as a method to reduce the duration and severity of colds, sufficient Zn2+ ions must be available to do the job. None of the follow-up studies used the same formulation as the original Eby, Davis, and Halcomb study, and none achieved results nearly as good. To obtain the desired quick results, the lozenge ZIA value should be at least 100. This means that salivary Zn2+ ion concentration should be 7.4 mMol, application of Zn2+ ions from lozenges should occur over a 30-minute period, and lozenges should be taken 9 times per day.

    Increased usage rate or stronger lozenges shorten colds in clinical practice even more than reported in published studies. Early use of ZIA 100 lozenges, perhaps within a few minutes or a few hours of the first observed common cold symptom, most often aborts incipient colds. After a few lozenges, no further treatment is usually required.

    What is most surprising about the published research reviewed here is the near total lack of fidelity by other researchers to the original discovery or to each other. The first tenet of scientific research is exact duplication of experiments by others to determine the validity of the original research.

    Apparently, other than the interview with Pellegrini concerning the development of the lozenges used in the Medical Research Council Common Cold Unit trial led by David A. J. Tyrrell (Al-Nakib et al. report), no attempt appears to have been made to replicate the solution chemistry of the original Eby et al. zinc gluconate lozenges.

    In each case, research appears to have been led or inhibited by commercial, not scientific, interests. Makers of each of the commercial compositions tested were apparently uninterested in the discovery unless they could quickly "make zinc lozenges taste like candy."

    Had researchers known that fructose was the only sweet carbohydrate tablet base suitable for use with zinc gluconate, the disappointment with flavor-masking could have been avoided, and zinc gluconate would not have developed its reputation of being objectionable in taste or inefficacious. Countless experiments by the present author showed fructose to be the only suitable tablet base for zinc gluconate.

    Unfortunately, the Italian company that sponsored the MRC zinc gluconate lozenge research was purchased by a company uninterested in the over-the-counter common cold market. Those Italian lozenges were the first fully flavor-masked zinc gluconate lozenges and they could have provided considerable relief to common cold suffers had they been commercialized.

    Other tightly bound zinc compounds and zinc compounds that release no Zn2+ ions at pH 7.4 cannot shorten colds. However, they do not lengthen colds either. Nearly all over-the-counter zinc lozenges available in the retail trade are of this type. Currently, lozenges advertised to contain zinc gluconate and zinc oxide are about 99.99% zinc oxide to eliminate objectionable taste and aftertaste from zinc gluconate reactions with dextrose tablet base.

    One may question the validity of negative ZIA value estimates, but the fact remains that lozenges releasing negatively charged zinc species (ZnLN-) increased the duration of common colds in a dose-response manner relative to placebo.

    One best explanation for the increase in duration is elimination of endogenous (native) Zn2+ ions from oral and nasal tissues by ZnLN-. Zn2+ ions are highly concentrated (4 to 20 mMol) in mast cell and basophil granules. Considerable Zn2+ ions are released during degranulation of these cells during inflammation. Clearly, ZnLN- released from these lozenges binds endogenous Zn2+ ions present in oral and nasal tissues and fluids as there are few other positively charged biochemicals to bind. If release of Zn2+ ions from mast cells during inflammation has the function of inhibiting viral replication, stimulating T-cells, stabilizing cell membranes, regulating mast cell homeostasis, catabolizing histamine, and stimulating interferon production during common colds as they do in vitro (See Chapter 2), then one could expect that common colds would be lengthened by neutralizing endogenous Zn2+ ions with ZnLN- to render them biologically unavailable at physiologic pH.

    Why the 1992 zinc gluconate-glycine formulation was reported to be effective with its negative ZIA value and glycine excess is uncertain. Perhaps the irritating acid effect was more than offset by astringency of Zn2+ ions at pH 5.0. Negatively charged zinc species were not the predominant species at pH 7.4, as the great majority (85%) was present as neutrally charged zinc glycinate. In the opinion of the present author, important errors found by Berthon and the present author cast doubt upon the validity of the ZGG study.

    Authors of several studies discussed in this chapter may disagree with conclusions expressed by the present author concerning physiologic availability of Zn2+ ions in their studies. The present author would have benefited -- and would have been pleased -- had those other authors been correct in their assertions of full bioavailability of Zn2+ ions and equivalence to the original Eby study.

    Conclusions presented about their claims are opinions of the present author based upon evidence and findings by neutral experts in various fields including solution chemistry, physiology, medicine, drug manufacturing, and pharmacology.

    Chapter 4 References

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    2. Gwaltney JM Jr. Rhinovirus. In: Mandell GL, Douglas RG Jr, Bennett JE, eds. Principles and Practices of Infectious Diseases. New York:John Wiley and Sons; 1979: 1124-1134.

    3. Kelly RW, Abel MH. Copper and zinc inhibit the metabolism of prostaglandin by the human uterus. Biology of Reproduction. 1983;28:883-889.

    4. Halcomb WW. Mesa, Arizona. Personal communication, 1992.

    5. Giec L, Wnuk-Wojnar AM, Trusz-Gluza M, et al. Epide- miologic evaluation of the coronary risk in physical workers on nonferrous metalworks. Part II. Coronary heart disease. Przegl Lek. 1980;37: 507-510. (English translation available)

    6. Chandra RK. Excessive intake of zinc impairs immune responses. Journal of the American Medical Association. 1984;252:1443-1446.

    7. Korant BD, Kaurer JC, Butterworth BE. Zinc ions inhibit replication of rhinoviruses. Nature. 1974; 248:588-590.

    8. Merluzzi VJ, Cipriano D, McNeil D, et al. Evaluation of zinc complexes on the replication of rhinovirus 2 in vitro. Research Communications in Chemical Pathology and Pharmacology. 1989;66: 425-440.

    9. Geist FC, Bateman, JA, Hayden FG. In vitro activity of zinc salts against human rhinoviruses. Antimicrobial Agents and Chemotherapy. 1987;31: 622-624.

    10. Al-Nakib W, Higgins PG, Barrow I. Prophylaxis and treatment of rhinovirus colds with zinc gluconate lozenges. Journal of Antimicrobial Chemotherapy. 1987;20: 893-901.

    11. Tyrrell DAJ. MRC AIDS Directed Programme, Public Health Laboratory Service, Centre for Applied Microbiology and Research, Porton Down, Salisbury, SP4 0JG, England. Personal communication, 1993.

    12. Smith DS, Helzner EC, Nuttall CE Jr, et al. Failure of zinc gluconate in treatment of acute upper respiratory tract infections. Antimicrobial Agents and Chemotherapy. 1989;33:646-648.

    13. Briggs, Finch P, Matulewicz MC, et al. Complexes of copper(II), calcium, and other metal ions with carbohydrates: Thin-layer ligand-exchange chromatography and determination of relative stabilities of complexes. Carbohydrate Research. 1981;97:181-188.

    14. Bannan B. General Nutrition Products, Greenville, SC. Unpublished data, 1989.

    15. Weismann K, Jakobsen JP, Weismann JE, et al. Zinc gluconate for common cold. Danish Medical Bulletin. 1990;37:279-281.

    16. Stör KB. Ahlgens International, Hvidovre, Denmark. Personal communication, 1992.

    17. Eby GA, Davis DR, Halcomb WW. Effect of zinc orotate lozenges with zinc gluconate nasal spray in common cold treatment - a double-blind study. Unpublished, 1984.

    18. Harisch G and Kretschmer M. Some aspects of a non-linear effect of zinc ions on the histamine release from rat peritoneal mast cells. Research Communications in Chemical and Pathological Pharmacology. 1987;55:39-48.

    19. Tucci ER, Ke CH, Li NC. Linear free energy relationships for proton dissociation and metal complexation of pyrimidine acids. Journal of Inorganic Nuclear Chemistry, 1967;29:1657.

    20. Aoki FY. Distribution and removal of human serum albumin-technetium 99m instilled intranasally. British Journal of Clinical Pharmacology. 1976;3:869-878.

    21. Castleman M. Cold Cures. New York:Fawcett Columbine;1987:ch 19.

    22. McCutcheon ML, Anderson JL and Cotton GE. University of Minnesota at Duluth. Unpublished data, 1987.

    23. Schennum B. Quantum Inc., Eugene, Oregon. Unpublished data, 1989.

    24. Berthon G, Germonneau P. Histamine as a ligand in blood plasma. Part 6. Aspartate and glutamate as possible partner ligands for zinc and histamine to favor histamine catabolism. Agents and Actions. 982;12: 619-629.

    25. Martin RB. pH as a variable in free zinc ion concentration from zinc-containing lozenges (letter). Antimicrobial Agents and Chemotherapy. 1988;32: 608-609.

    26. Farr BM, Conner EM, Betts RF. Two randomized controlled trials of zinc gluconate lozenge therapy of experimentally induced rhinovirus colds. Antimicrobial Agents and Chemotherapy. 1987;31:1183-1187.

    27. Korant BD. E. I. du Pont de Nemours Co., Wilmington, DE. Personal communication, 1992.

    28. Hill I, Locust NJ; Eby GA, Austin TX. Unpublished data, 1989.

    29. Berthon G, May PM, Williams DR. Computer simulation of metal-ion equilibria in biofluids. Part 2. Formation constants for zinc(II)-citrate- cysteinate binary and ternary complexes and improved models of low-molecular-weight zinc species in blood plasma. Journal Chemical Society, Dalton. 1978;1433-1438.

    30. Martell AE, Smith RM. Critical Stability Constants. New York: Plenum Press; 1991:vols 1-6.

    31. Sillùn LG, Martell AE. Stability Constants of Metal-Ion Complexes. Special Publication No. 17. London:Burlington House; 1964.

    32. Furia TE. Sequestrants in food. In: Furia TE, ed. CRC Handbook of Food Additives. 2nd ed. West Palm Beach:CRC Press; 1972.

    33. Adler S, Fraley DS. Acid-base regulation, cellular and whole body. In: Arieff AI, DeFronzo RA, eds. Fluid, Electrolyte, and Acid-Base Disorders. New York:Churchhill Livingstone. 1985;1:227.

    34. Guyton AC. Regulation of acid-base balance. In: Textbook of Medical Physiology. New York:W. B. Saunders Co. 1986:439.

    35. Nordenström BE. Biologically Closed Electric Circuits. Clinical, Experimental and Theoretical Evidence for an Additional Circulatory System. Stockholm:Nordic Medical Publications; 1983.

    36. Farr BM, Gwaltney JM. Zinc gluconate for the common cold: An evaluation of placebo matching. Journal of Chronic Diseases. 1987;40: 875-879.

    37. Douglas RM, Miles HB, Moore BW. Failure of effervescent zinc acetate lozenges to alter the course of upper respiratory tract infections in Australian adults. Antimicrobial Agents and Chemotherapy. 1987;31:1263- 1265.

    38. Williams RJE. F. H. Faulding & Company, Adelaide, South Australia, Personal communication, 1987.

    39. Mohrle R. Effervescent tablets. In: Lieberman HA, Lachman L, Schwartz JB. eds. Pharmaceutical Dosage Forms: Tablets. New York:Marcel Dekker, Inc.; 1989:1.

    40. Hacht B, Berthon G. Metal ion-FTS nonapeptide interactions. A quantitative study of zinc(II)-non-apeptide complexes (thymulin) under physiological conditions and assessment of their biological significance. Inorganica Chimica Acta. 1987;136: 165-171.

    41 Berthon G, Varsamidis A, Blaquiere C, et al. Histamine as a ligand in blood plasma. Part 7. Malate, malonate, maleate and tartrate as adjuvants of zinc to flavor histamine tissue diffusion through mixed-ligand coordination. In vitro tests on lymphocyte proliferation. Agents and Actions. 1987;22:231-247.

    42. Godfrey JC, Conant Sloane B, Smith DS. Zinc Gluconate and the Common Cold. The Journal of International Medical Research. 1992;20:234.

    43. Zarembo JE, Godfrey JC, Godfrey NJ. Zinc(II) in Saliva: Determination of concentrations produced by different formulations of zinc gluconate lozenges containing common excipients. Journal of Pharmaceutic Sciences. 1992; 81:128-130.

    44. Alemdaroglu T, Berthon G. Trace metal requirements in total parenteral nutrition II. Potentiometric study of the metal-ion equilibria in the zinc-histidine, zinc-glycine, zinc-cysteine-histinidine, zinc-glycine- histidine and zinc-glycine-cysteine systems under physiological conditions. Journal of Electroanalytical Chemistry and Interfacial Electrochemistry. 1981;128:49-62.






    Chapter 5. Central Finding of Linear Relation between ZIA and Efficacy

    Executive summary Chapter 5 presents the central finding of linear relationship between zinc ion availability (ZIA) values and reductions in the duration of common colds. Linearity is an important discovery made possible only from rigorous analyses of the physical and chemical properties of the eight distinctly different proprietary lozenges studied. Critical ZIA factors, ZIA values, and comparative taste tests of lozenges are presented. Data show a relationship between ZIA and efficacy but no relation between ZIA and other factors.

    Hydrated Zn2+ ions at pH 7.4 have been shown to have a broad range of effects in fighting common colds. In vivo, zinc gluconate lozenges with high daily ZIA values have rapidly reduced cold duration and severity; lozenges with moderate ZIA values show only late efficacy against duration; and, with a minor exception, lozenges with low, zero, and negative daily ZIA values failed in clinical studies.

    Clearly, different results have occurred (as mentioned in Chapter 4), and a method to reconcile differences is needed. By organizing the data using ZIA values and changes in common cold duration, a linear relationship between ZIA and reductions in duration in colds results. A surprising increase in duration usually occurs using lozenges yielding negatively charged zinc species.

    Table 7. ZIA Factors (zinc, fraction Zn2+, dissolution times, doses/day, and saliva generated)

    Study Lozenge	 Amount of  Fraction  Dissolution  Doses Saliva	Lozenge 
    		 zinc (mg)  Zn2+      Time (min)  /day 	(grams) (grams)
    ________________________________________________________________________
    
    Eby zinc gluconate
    in nonsoluble 
    tablet		  23.0	    0.30	30	    9	 15.0	0.66
    
    MRC zinc gluconate
    in fructose 
    tablet		  23.0	    0.30	19	    9	22.0	1.00
    
    McNeil zinc gluconate
    in mixed tablet	  11.5	    0.30	15	   10	17.5	1.56
    
    Danish 4.5 mg zinc 
    gluconate in 
    maltitol lozenge   4.5	    0.30	15    	    12	17.0	3.00
    
    Zinc orotate 
    lozenge		  37.0      0.00	40	     6	18.0	3.00
    
    Zinc aspartate 
    lozenge		  24.0	    0.00	14	     9	18.0	3.00
    
    Zinc gluconate 
    and citric acid	  23.0      0.00	15	     9  35.0	4.50
    
    Zinc acetate 
    with tartaric,acid 
    & sodium bicarb-
    onate in mannitol 10.0	    0.00	10	     9	44.0	3.00
    
    Zinc gluconate-
    glycine	(10 mole) 23.7	    0.00	15	     9  26.3	4.50
    _____________________________________________________________________
    

    ZIA Factors

    Data collected during analysis of lozenge performance and daily ZIA calculations include mg zinc, fraction of zinc as hydrated Zn2+ ions, length of time to dissolve lozenges in minutes, number of doses/day, and saliva volume produced by zinc lozenges (numerically equivalent to weight of saliva minus lozenge weight). Data are summarized in Table 7.

    Data were obtained by lozenge dissolution/expectoration experimentation using lozenges based upon descriptions of the lozenges in the original clinical reports or upon lozenge formulations and data supplied by the original authors or lozenge manufacturers. Every possible effort was made to use the exact lozenges used by the trialists or replications exactly duplicating the chemical and physical properties of the lozenges.

    Comparative ZIA Values

    Comparison of zinc ion availability (ZIA) values for clinical studies shows close relationship to actual clinical results. The finding of reasonable linearity of those relationships represents the central finding of this report. For scientific objectivity, results from experimental zinc lozenge treatments of common colds in the various published studies must be compared in an identical manner through ZIA reduction or increase in common cold duration. ZIA is the concentration of Zn2+ ions applied to the oral mucosa over time, which equals: [0.7697 times mg zinc, times fraction as Zn2+ ion, times time to dissolve (minutes), times number of doses per day], divided by [total mg saliva minus mg lozenge weight as approximation of saliva volume in ml]. The constant 0.7697 sets the Eby and co-worker reference value of 100 for ease in comparison. (See Chapter 3, Zinc Ion Availability Values, for more information on ZIA values and their calculation.)

    Table 8. Study lozenges, ZIA values, electronic charge, and reduction in duration of colds.

    _________________________________________________________________________
    
    Study Lozenges		ZIA values	Charges		Efficacy	  
    _________________________________________________________________________
    
    Eby (23 mg zinc) 
    zinc gluconate in							
    nonsoluble tablets	 100		2+,1+,0		7-day reduction in
    							duration of colds
    MRCC (23 mg zinc)
    zinc gluconate in
    fructose tablets	  44		2+,1+,0		4.8-day reduction in 							duration of colds
    							
    
    McNeil (11.5 mg zinc) 
    zinc gluconate in
    mixed base  		  25 		2+,1+,0		1.6-day	reduction in
    							duration of colds
    									
    Danish 4.5 mg zinc 
    gluconate in maltitol	 13.4		2+,1+,0		none
    							
    Zinc orotate lozenges	  0		0		none
    
    Zinc aspartate lozenge	  0		0		none
    
    Zinc gluconate and 
    1.33 mole citric acid    -11 *		0, N-   	1-day increase in
    							duration of colds
    							& worsened symptoms
    
    Zinc acetate with very 
    large molar excesses	 
    of tartaric acid and 					
    sodium bicarbonate					 
    in mannitol lozenge	-55 *		0, N-		4.4-day increase in
    							duration of colds
    							& worsened symptoms
    Zinc gluconate-glycine 
    in hard candy lozenge
    (10 mole glycine 1992)	Unknown		0, N-	        1.3 day reduction in
    		       (negative)			duration of colds
    ____________________________________________________________________________
    
         *  Negative ZIA values were determined by projection.

    Table 8 data (excluding negative values) were analyzed to determine correlation between zinc ion availability (ZIA) and change in duration of common colds in these studies. Spearman's rank difference correlation method was used. Spearman's is most useful with samples of small size.(1) The statistic was r (rho) = 0.96. The test of the hypothesis that the population correlation is zero is significant beyond 0.02 level in a 2-tailed test. From a statistician's perspective, "one is warranted in rejecting the null hypothesis that there is no relationship between ZIA values and reduction in duration in common colds." Additional data using lozenges above ZIA value 70 would be helpful in confirming and extending these observations.

    By comparing daily ZIA values and reduction in duration of common colds, a linear relationship can be established between these (Figure 19), and linearity is the central finding of this report. Reasonable linearity through the range shows that there is a good relationship between ZIA values and reduction in duration of common colds in these studies. This linearity can be used to predict the efficacy of clinically untested zinc lozenges based upon ZIA values of experimental lozenges having zinc complexed with very weak ligands and no added zinc chelators. Linearity shows that seemingly divergent results of studies by Eby, Douglas, Farr, Smith, and others are reconciled by considering zinc ionization availability (ZIA).

    From the reports analyzed, ZIA and Zn2+ ion, but not zinc compounds, are correlated with the reduction in duration of common colds. Correlation is consistent with the findings of Merluzzi and co-workers for in vitro activity of zinc against rhinoviruses.(2) Reduction in duration is also correlated with Zn2+ ion-laden saliva concentration, but it is not a reliable indicator of future lozenge efficacy, as duration of oral contact by Zn2+ ions must be considered. One can also argue that efficacy is linearly correlated only with the concentration of zinc gluconate, because only zinc gluconate-derived Zn2+ ions have shown efficacy in published studies reported to date. However, unreported experimental evidence with zinc acetate lozenges in many subjects clearly demonstrates the importance of availability of Zn2+ ions in shortening colds.

    Lozenges having a positive ZIA value reduce the duration of common colds in a dose-response manner.  ZIA 25 lozenges reduce duration of colds by about 1-1/2 day, while lozenges having a ZIA value of 44 reduce the duration of colds by 4.8 days, and lozenges having a ZIA value of 100 reduce the duration of colds by 7 days.  Lozenges containing tightly bound zinc complexes have a zero ZIA and do not change the duration of colds.  Lozenges releasing negatively charged zinc species at physiologic pH increase the duration of common colds in a dose-response manner.

    Figure 19. Relationship of zinc ion availability (ZIA) values and reduction in duration of common colds in days (y = 0.077x - 0.16).

    The highly efficacious lozenges tested by Eby and colleagues in 1984 had a ZIA value more than twice as high as the next highest lozenge (MRC), and much higher than the other lozenges. Absence of a significant effect from Zn2+ ions on the rate and amount of viruses excreted by volunteer in the study by Al-Nakib and co-workers at the Medical Research Council Common Cold Unit,(3) does not mean antirhinoviral effect is absent using lozenges with higher, more efficacious ZIA values and higher Zn2+ ion salivary concentrations. A ZIA value of 50 and a 5 mMol salivary Zn2+ ion concentration appear to be thresholds for significant early Zn2+ ion effects on the severity and duration of colds. One might expect antirhinoviral activity, interferon induction, histamine mitigation, and cell membrane stabilization and drying effects to occur at sufficiently high ZIA, perhaps at about ZIA 100 and 7.4 mMol Zn2+ ion concentration, where a much stronger clinical effect was observed.

    Linearity is attributed to diffusion of hydrated Zn2+ ions across biologic membranes and through tissues according to Fick's first and second laws with electrophoretic effects. These observations are the most readily observable examples of biologically closed electric circuits, as first proposed by Nordenström.(4)

    Along with the strong repelling effects of nasal mucus and cilia on foreign substances introduced to the nose, as noted by Aoki(5) and many others, the differential repels intranasally introduced Zn2+ ions from mucosal surfaces, further explaining lack of efficacy from zinc nasal sprays.

    The importance of the amount of zinc available, the fraction as Zn2+ ion, lozenge dissolution times, saliva generation, and dosages per day can all be understood as equally important in this system, as no factor was emphasized over another. Within certain limits, the system demonstrates an important tool needed to design successful common cold lozenges. Dissolution times and saliva production are as important as amount of Zn2+ ions released and appear to be important areas for developmental efforts, while increasing the number of lozenges used per day is a simple method of increasing efficacy.

    Even though the system shows linearity throughout the range studied, the actual curve is probably parabolic with an upward slope from negative ZIA values through about ZIA 500. At some point between about ZIA 500 and perhaps ZIA 1000, the curve may level off. At some point over 1000, the curve may develop a downward slope demonstrating mast cell degranulation and general tissue injury caused by toxic concentration of Zn2+ ions as described by in vitro and toxicity studies.

    Projection of Negative ZIA Values

    Negative ZIA values for 2 of the 3 zinc lozenges having excess strong zinc chelators were estimated by straight-line projection of the non-negative values using the equation found in the legend of Figure 19. The zinc gluconate-glycine data-point, actually a horizontal line at +1.27 days, would be located in the upper-left quadrant of Figure 19, but it was omitted as it would have caused confusion and it was meaningless information. No negative value was used in determining r or the curve. Lengthened colds were associated with several lozenge formulations having negative ZIA values -- that is -- lozenges releasing negatively (and neutrally) charged zinc species at pH 7.4.

    One may question the validity of negative ZIA value estimates, but the fact remains that lozenges releasing negatively charged zinc species (ZnLN-) increased the duration of common colds in a dose-response manner relative to placebo.

    As discussed in Chapter 2, Zn2+ ions are highly concentrated (4 to 20 mMol) in mast cell and basophil granules. Zinc2+ ions are released during degranulation of these cells during inflammation. ZnLN- released from these lozenges binds native Zn2+ ions present in oral and nasal tissues and fluids. If release of Zn2+ ions from these cells during inflammation has the function of inhibiting viral replication, stimulating T-cells, stabilizing cell membranes, regulating mast cell homeostasis, catabolizing histamine, and stimulating interferon production during common colds as they do in vitro, then one must assume that common colds would be lengthened by neutralizing native Zn2+ ions with ZnLN- to render them biologically unavailable at physiologic pH -- thus making colds worse.

    Taste Scale and ZIA

    Lozenge taste is a crucial criterion for commercialization of zinc lozenges. Each of the studies following Eby and co-workers used lozenges selected for pleasant tastes. Zinc gluconate lozenges known not to have a pleasant taste were not considered for testing. Even though the McNeil-sponsored lozenges had a bitter taste at the time of the study, it is safe to assume McNeil and General Nutrition representatives did not know zinc gluconate in combination with dextrose molecule would become dreadfully bitter after aging, or if they did, they had no idea how to correct the flavor-masking problem.

    Had the eight studies been rated on a taste scale, relationships concerning ZIA values and taste could have been better developed. Volunteers have carefully taste-tested each of the lozenges (or nearly exact chemical copies) used in the eight clinical studies and offer the following subjective, relative ranking of zinc lozenge taste acceptability. Although taste preferences are highly subjective, differences noted were obvious. On a scale of 0 to 10 (with 0 being dreadfully bitter, 5 being acceptable but not particularly pleasant, and 10 being as pleasant as candy or no taste sensation other than astringency), the lozenges are rated in Table 9 below.

    Taste acceptability is dependent upon the zinc complex, other lozenge ingredients and their reactions with zinc, but taste acceptability is not dependent upon ZIA.

    The 1984 lozenges tested by Eby and co-workers had not only the taste of zinc gluconate but also the taste of dicalcium phosphate, and both active and placebo lozenges primarily tasted chalky. Lozenges used by the MRC relied upon strong, sweet Italian flavors and fructose to preserve both taste and promote efficacy through absolute compliance. Without other soluble ingredients, taste was stable and reasonably pleasant. The McNeil lozenges were so bitter from complexation of zinc gluconate with dextrose that clinical failure and lack of compliance resulted. The Australian lozenges relied upon greatly reduced dosage and chelation by tartaric acid and sodium bicarbonate to eliminate astringency, also eliminating efficacy of the modified zinc acetate lozenges. The taste associated with their lozenges was of flavored tartaric acid.

    Table 9. Lozenge taste, salivary pH, near aftertaste and overnight aftertaste.

    _____________________________________________________________________
     	
    Study lozenges	   ZIA     Salivary  Lozenge   Near 	   Overnight 
    		   values  pH	     taste     aftertaste* aftertaste  
    ________________________________________________________________________
    
    Eby zinc gluconate 
    (23 mg zinc)
    tablets		      100     5.5	5	  6		8
    
    MRC zinc gluconate 
    (23 mg zinc)
    fructose lozenge       44     5.4	9	  7		8
    
    McNeil zinc gluconate 
    (11.5 mg zinc) 3-g 
    mixed sweeteners 
    lozenge		       25     6.4	0	  3		5
    	
    Danish zinc gluconate 
    (4.5 mg zinc)
    maltitol lozenges     13.4     6.4	7	  8		9
    
    Zinc orotate
    (37 mg zinc) 
    3.6-g lozenges         0.0      7	6	  8 	       10
    
    Zinc aspartate 
    (24 mg zinc) lozenge   0.0      7	8	 10	       10
    
    Bristol-Myers zinc 
    gluconate (23 mg zinc)
    and extramolar citric 
    acid hard candy	
    (sucrose/corn syrup)
    lozenges	       -11      4.3  	 8   	 10 	       10
    
    Australian zinc acetate
    (10 mg zinc) effervescent 
    lozenges with tartaric acid,
    sodium bicarbonate in 
    mannitol 	       -55      4.1  	 7	  8		 9
    
    Godfrey zinc 
    gluconate-glycine    Unknown    5.0 	 9	  9		10
    		    (negative)
    _______________________________________________________________________
    

    * Near aftertaste is aftertaste observed during the first 2 hours after completion of lozenge.

    The Bristol-Myers lozenges relied upon chelation by citric acid and orange flavor oils to eliminate objectionable taste with a resulting loss of efficacy. Insoluble zinc orotate in lozenges was essentially tasteless but lozenges were orally abrasive. Zinc aspartate lozenges were naturally pleasant-tasting, were highly chelated, released no Zn2+ ions, and had no efficacy. Godfrey designed zinc gluconate-glycine (10 mole) lozenges that were pleasant-tasting but yielded no Zn2+ ions at physiologic pH 7.4. Although Godfrey's lozenges were pseudo-astringent, such is the result of some Zn2+ ion being available at salivary pH 5.0 but not at the higher physiologic pH capable of affecting a reduction in common cold duration. All pH tests were conducted with both Nester and Corning pH meters calibrated with fresh Ricca pH 4, 7, and 10 reference buffer solutions. Natural salivary pH varies between pH 6.2 and 7.2, with pH 6.2 to 6.5 being observed in these tests.

    Concession to Taste Through Use of a Double Loading Dose

    Before the Eby 1984 clinical trial, the author determined that the minimum dosage should be about 50 mg zinc from zinc gluconate every 2 hours, not the 23-mg dosage used in the trial. However, lozenge harshness suggested some patients would reject treatment, and the dosage was compromised to 23 mg doses every 2 hours. The full dosage (46 mg zinc) was retained as a loading dose because considerable anecdotal evidence was available to the author that the first dose taken was important to achieve extremely rapid treatment responses when taken sufficiently early in a cold.

    Treatment responses more rapid than documented occur frequently in field use. Faster responses are possible using larger doses or more frequent dosing with zinc gluconate or zinc acetate. Extremely rapid responses occur if treatment is started upon announcement by a throat or nose tickle of an incipient cold.

    No other researchers incorporated a loading dose into their protocols. The ZIA value of the loading dose described by Eby and co-workers was therefore 4.6 times higher than the ZIA value from the first lozenge used in the MRC trial, eight times the McNeil lozenge value, and so forth.

    Zn2+ Ions and Zinc Compound Molar Concentration with ZIA Values

    Although ZIA values are the best indicators of successful lozenges, Zn2+ ion concentrations are noteworthy as concentrations are important components of ZIA values (see Table 10). Clear distinctions can be detected in salivary Zn2+ ion concentration and zinc compound concentration. The most effective lozenges produced the highest ZIA values and salivary Zn2+ ion concentrations, while the largest concentration of zinc in saliva was found with the ineffective zinc orotate lozenges. For comparison, normal zinc serum concentration is 0.015 + 0.006 mMol; and minimum antirhinoviral- and interferon-inducing concentrations of Zn2+ ions are 0.05 mMol according to Merluzzi2 and Geist and colleagues,(6) or 0.10 mMol according to Korant and co-workers.(7) Zinc gluconate releases 30 percent of its zinc as Zn2+ ion at physiologic pH 7.4.

    Table 10. Zn2+ ion and zinc compound salivary molar concentration compared with ZIA values.

    ___________________________________________________________________________
    
    Study Lozenge			ZIA		Zn2+ mMol   	Zinc 
    				Value		at pH 7.4	mMol	
    ___________________________________________________________________________ 
    
    Eby 23 zinc gluconate in 
    nonsoluble tablets		100.0		   7.4		24.7
    	
    MRC 23 zinc gluconate in 
    fructose tablets		  44		   5.0		16.8
    
    McNeil 11.5 mg zinc 
    gluconate lozenges		  25		   3.3		11.1
    
    Danish 4.5 mg zinc gluconate 
    lozenges			  13.4		   1.5		 5.0
    
    Zinc orotate lozenge	           0.0		   0.0		31.0
    
    Zinc aspartate lozenge		   0.0		   0.0		20.0
    	
    Zinc gluconate-citrate lozenges	 -11		   0.0		10.0
    
    Zinc acetate-tartarate
      -carbonate lozenges	   	  -55		   0.0	         3.0
    
    Zinc gluconate-glycine lozenges  Negative	   0.0		13.9
    				(unknown)
    _______________________________________________________________________
    

    In 1989, Vincent J. Merluzzi, and co-workers showed antirhinoviral effects of zinc in HeLa cells were directly related to the amount of Zn2+ ion available and unrelated to the total amount of zinc complex available.(2)

    Similarly, the present author has shown the reduction in duration of common colds to depend upon ZIA, which depends upon Zn2+ ion concentration and time of contact with oral mucosal membranes, -- not the amount of zinc compound.

    Salivary Zn2+ ion concentration is an oversimplified and misleading indicator of efficacy. High salivary Zn2+ ion concentrations may have a low ZIA value if lozenges dissolve too quickly. The time that Zn2+ ion is applied (as time to dissolve lozenges) and number of doses per day are important variables in determining ZIA values of experimental lozenges.

    Good examples of the limited relationship in ZIA values between chemically similar 23-mg zinc as zinc acetate lozenges may be seen in Chapter 7, Table 11.

    Chapter 5. References

    1. Guilford JP, Fruchter B. Fundamental Statistics in Psychology and Education. 6th edition. New York:McGraw-Hill; 1978

    2. Merluzzi VJ, Cipriano D, McNeil D, et al. Evaluation of zinc complexes on the replication of rhinovirus 2 in vitro. Research Communications in Chemical Pathology and Pharmacology. 1989;66: 425-440.

    3. Al-Nakib W, Higgins PG, Barrow I, et al. Prophylaxis and treatment of rhinovirus colds with zinc gluconate lozenges. Journal of Antimicrobial Chemotherapy. 1987;20: 893-901.

    4. Nordenström BE. Biologically Closed Electric Circuits, Clinical, Experimental and Theoretical Evidence for an Additional Circulatory System. Stockholm:Nordic Medical Publications; 1983.

    5. Aoki FY. Distribution and removal of human serum albumin-technetium 99m instilled intranasally. British Journal of Clinical Pharmacology. 1976;3:869-878.

    6. Geist FC, Bateman, JA, Hayden FG. In vitro activity of zinc salts against human rhinoviruses. Antimicrobial Agents and Chemotherapy. 1987; 31:622-624.

    7. Korant BD, Kaurer JC, Butterworth BE. Zinc ions inhibit replication of rhinoviruses. Nature. 1974; 248:588-590.






    Chapter 6. - Effects of Flavor-Masking on Efficacy

    Executive Summary Chapter 6 describes flavor masking techniques for zinc gluconate lozenges. One method, chelation by strong ligands such as 30% extramolar citric acid, or 10-fold extramolar glycine eliminates Zn2+ ions at physiologic pH and destroys efficacy. Addition of strong chelators to zinc gluconate lozenges was erroneously believed to be necessary by others, because dextrose and all carbohydrates based upon dextrose react with zinc gluconate in solid state reactions resulting in bitterness upon lozenge aging. Fructose, the isomer of dextrose, does not adversely react with zinc gluconate and is the only suitable sweetener for use in flavor masked zinc gluconate lozenges. Either flavor masked zinc gluconate lozenges, or zinc gluconate lozenges having positive ZIA values are each possible separately, but not together (unless the tablet base is fructose with no other soluble carbohydrates). Zinc gluconate lozenges having a ZIA value greater than 50 are not possible without undesirable increases in zinc content.

    Two basic methods of flavor-masking zinc lozenges exist. The first method involves strong chelation of zinc in zinc gluconate to another compound of zinc. Strong chelation always results in loss of efficacy in common cold treatment. The second method, the only one to allow efficacy against the duration of common colds, involves no additional chelation. Examples include zinc gluconate with a non-reactive tablet base with or without a flavor-masking agent (strong flavor oil) or substitution of zinc acetate for zinc gluconate as zinc acetate naturally requires no flavor mask.

    When zinc gluconate is tasted in its pure form, or when compressed into tablets containing no other soluble ingredients or when compounded with fructose and Methocel(r), zinc gluconate has a mildly objectionable, bland, chalky taste and aftertaste. The aftertaste can last 24 hours. In solutions of zinc gluconate, the main zinc species found at physiologic pH is zinc gluconate-hydroxide (see Figure 1). Zinc gluconate-hydroxide is a neutral zinc compound that can enter cells causing objectionable taste, aftertaste, and tissue injury. Considerable improvement in lozenge taste -- without an objectionable aftertaste -- is obviously necessary to develop a commercially successful product. Zinc gluconate lozenges can have high ZIA values, or lozenges can be pleasantly flavored, but both characteristics are not possible simultaneously in lozenges containing 23 mg zinc or less for reasons described below.

    For practical purposes, use of zinc acetate solves the taste/ZIA incompatibility problem found in zinc gluconate lozenges. When compounded into 5-gram sugar lozenges, zinc acetate lozenges can have high ZIA values, are flavor-stable, and have pleasant tastes with no added flavor mask.

    Strong Chelation of zinc

    Management of metallic ions in food has received considerable attention by the food industry. Metallic ions of iron, copper, and zinc present in some food products, even in minuscule amounts, can cause adverse effects on food flavor and integrity. If those metallic ions are allowed to remain in food products, even in very low concentrations, metallic ions can greatly reduce shelf life of fats, oils, and other foods subject to spoiling and oxidation.

    From a food manufacturing perspective, however, metallic chelators serve to stabilize or enhance numerous properties identified with wholesome food, including flavor, color, and texture.(1) Addition of most food chelators does not impair absorption of zinc from foods passing through the intestinal tract because stomach acid dissociates zinc from the ligand. Several efforts were made by companies to find a chelating flavor mask for zinc gluconate.

    Citric acid in the Bristol Myers zinc gluconate lozenges (see Chapter 4.C.1) and tartaric acid in the Australian zinc acetate lozenges (see Chapter 4.C.2) are two food acidifiers that have been directly used to chelate zinc lozenges to improve their flavor. Sodium bicarbonate in the Australian lozenges provided a source of carbonic acid in solution to react with zinc gluconate to form nonsoluble, nonionizable zinc carbonate. Chelators, by definition, reduce or eliminate Zn2+ ions in solutions at physiologic pH.

    Highly chelated compounds of zinc, including zinc orotate (see Chapter 4.B.1) and zinc aspartate (see Chapter 4.B.2), have been shown to be without any effect on the duration of common colds. Zinc aspartate, zinc oxide, and zinc amino acid chelate lozenges -- all highly chelated and ineffective against colds -- are the zinc lozenges most likely to be encountered in health food stores.

    Glycine and other sweet amino acids were proposed by Zarembo, Godfrey and co-workers to be effective flavor masks for zinc gluconate and other ionizable zinc compounds (see Chapter 4.C.3). Contrary to claims of 93 percent Zn2+ ions being released into saliva from these lozenges, glycine (10 mole) releases no Zn2+ ions at pH 7.4 according to Berthon. Hard candy zinc gluconate lozenges compounded with glycine slowly change color from a light tan to bright orangish-brown during ambient summer storage conditions, suggesting a Mailard reaction occurs between sugars and glycine.

    Glycine has been rescinded from the FDA list of Generally Regarded As Safe (GRAS) ingredients (21 CFR §170.50) and has been prohibited as an additive to foods including candy lozenges and cough drops since 1971. Glycine is only allowed in prescription drugs under a U.S. Food and Drug Administration New Drug Application.(2) However, glycine is permitted as a food additive to improve the biologic quality of the total protein in a food containing naturally occurring, primarily intact protein but is not to be allowed in excess of 3.5 percent of the total protein.(3) 1998 Addendum: The U.S. Congress passed a law in 1995 decreeing all amino acids safe.

    Zinc gluconate lozenges were described in a technical bulletin published by Akzo Chemie Company of The Netherlands dated January 22, 1986.(4) Ten milligrams of zinc (77 mg zinc gluconate) were incorporated in 3.5 gram candy lozenges. The lozenge filler was sorbitol with 2 percent gum arabic (acacia). Zinc gluconate was added at 121 degrees C. to sorbitol and gum arabic. The mixture was batch cooked to 144 degrees C., and cooled to 77 degrees C. to add peppermint oil. The mixture was deposited in molds, and held overnight at 39 degrees C. The resultant product was crystal clear, had no taste of zinc gluconate, and had no astringency. Gum arabic (acacia) has a high molecular weight (240,000 to 580,000), is extremely soluble in water at twice its weight, and is acidic to litmus.(5) Gum arabic consists of (-)-arabinose, (+)-galactose, (-)-rhamnose, (+)-glycuronic acid, tannins and other chemicals. Gum arabic is incompatible with most metallic salts, including salts of zinc, lead, boron, and iron. Combination results in precipitation or jellification.(5)

    Zinc gluconate heated in sorbitol without gum arabic rapidly carbonizes and develops a foul, burnt odor producing lozenges having no research or commercial utility. The status of sorbitol as a zinc chelator is stated by Briggs and co-workers(6) to be only 4 times higher than dextrose (K1 = 0.04), but sorbitol may be a much stronger zinc chelator according to Zarembo and co-workers.(7) Zinc chelated to tight complexes with gum arabic in these lozenges would have no efficacy against common colds.

    Encapsulation of zinc gluconate powder, with the first layer being hydrophilic and second layer being hydrophobic, reduces bitterness, astringency, dryness, and roughness of zinc gluconate by about one-third when incorporated into lozenges according to a patent assigned to Warner Lambert Company.(8) Hydrocolloid materials including pectins, alginates, cellulose and its derivatives, gelatin, gums, mucilages, and mixtures are used. Some hydrocolloids are zinc chelators, and they react with zinc gluconate to eliminate Zn2+ ions, as well as to reduce and eliminate bitterness and astringency. Incorporation of treated zinc gluconate granules in non-fructose compressed lozenges results in damage to granule membranes with resultant delayed-onset bitterness.

    Although not technically chelation, microencapsulation of zinc gluconate with nonsoluble cellulose membranes was demonstrated by Eurand America, Inc., Vandalia, Ohio, in 1985 with the idea of incorporating zinc gluconate into chewing gum. The product effectively flavor-masked zinc gluconate by preventing release of zinc gluconate into saliva, resulting in essentially all zinc being swallowed and thereby rendering products incapable of producing an effect against common colds.

    South African researchers complexed zinc gluconate with EDTA, a powerful zinc chelator, resulting in no efficacy against duration of common colds when used as a nasal spray. Sprays also caused considerable pain.

    Various Non-Chelating Flavor Masks

    Zinc gluconate in the McNeil Consumer Products lozenges containing sucrose, fructose, mannitol and sorbitol (see Chapter 4.A.3) became very bitter over a month, demonstrating the problem in maintaining a flavor-stable product. Failure of the McNeil lozenges can be directly attributed to poor patient compliance as a result of lozenge bitterness. All sweet carbohydrates except fructose react with zinc gluconate to impart bitterness.

    From 1986 to 1992 the present author conducted experiments to mask zinc gluconate flavor. The main thrust of the research was to develop techniques not chelating zinc, while reducing bitterness. Generally, the antidote to bitterness is sweetness. Numerous attempts were made to find sweeteners that would reduce bitterness. Many zinc compounds were tested in many different bases. After over 1000 failures testing various zinc gluconate lozenge compositions, briefly noted below, the author developed two non-chelating methods of flavor-masking zinc lozenges.

    Lozenge formulations were tested using zinc gluconate and other zinc compounds in either hard boiled candy or directly compressed lozenges. All zinc gluconate lozenges and nearly all other zinc compounds tested (except zinc acetate), regardless of manufacturing technique, made with bases containing dextrose, sucrose, mannitol, sorbitol, xylitol, maltose, maltodextrins, lactose, other sweet tablet bases, and various combinations became very bitter within a few days to a few months.

    The addition of 50 mg sodium, calcium, or acid saccharin to zinc gluconate in lozenges eliminated bitterness and aftertaste from both zinc gluconate and other zinc compounds although saccharin complexes with Zn2+ ions. Lozenges became much too sweet resulting in an overly bitter saccharin taste and aftertaste. Efficacy against common colds may have been impaired by incorporation of saccharin. Lozenges were unpredictable in their flavor. Using identical lozenges, some taste testers complained lozenges were too sweet, while others complained of extreme bitterness. Perception of lozenge taste varied too widely with saccharin as a flavor mask to be of value for commercial development. Saccharin may also be objectionable as a potential carcinogen to patients. Therefore, incorporation of saccharin may preclude the fullest utilization of zinc lozenges. Incorporation of saccharin also caused severe headaches in several taste testers. Headaches did not occur in those taste testers when saccharin was not used in lozenges.

    Complexation of zinc in 1986 with saccharin by Syntheco Inc., Gastonia, North Carolina, for the present author resulted in an extremely sweet composition using less than 30 mg zinc saccharinate in a 5-gram lozenge. If zinc dosage was increased to therapeutic levels, flavor became extremely bitter. No formal tests against common colds were conducted with zinc saccharinate because of extreme bitterness.

    Addition of Magnasweet (mono-ammonium glycyrrhizinate), a flavor enhancer, increased the bitterness and astringency of zinc gluconate lozenges. Again, no tests against common colds were conducted because of extreme bitterness.

    Addition of other super-sweeteners including acesulfame K, aspartame, and various licorice extracts did not produce noticeable benefit to sweetness at chemically insignificant doses; and most are strong zinc chelators. Addition of phenyl acetaldehyde diisobutylacetal, a flavor mask used in extremely small amounts, had no beneficial effect and tended to increase the bitterness of zinc gluconate lozenges.

    Carbowax 8000 (polyethylene glycol molecular weight 8000), or PEG, coating of zinc gluconate granules using fluid bed agglomeration was performed by I. F. P., Inc. of Hayfield, Minnesota, in 1989 and 1990 for the author. Coatings were in weight-ratios of 10 percent, 50 percent, 100 percent, and 200 percent to zinc gluconate. Directly compressed lozenges of agglomerated sucrose (Sugartab(r) by the Edward Mendell Company in Carmel, New York) incorporating PEG-coated zinc gluconate were tested for flavor stability. After a few weeks, lozenges containing 25 percent and 50 percent coatings became bitter. After 1 to 4 months, lozenges containing higher amounts of coating became bitter. Compression ruptures PEG membranes, allowing chemical reactions between zinc gluconate and other lozenge ingredients. A gummy, solid residue in saliva resulted from oral dissolution of lozenges.

    Carbowax treatment of fructose produced lozenges containing zinc gluconate that did not become bitter upon aging, at least for the first 6 months.

    Carbowax 8000 coating of ground crystalline fructose (Krystar 300 by A. E. Staley Manufacturing Company, Decatur, Illinois) was possible only at low temperature and only when PEG was diluted with water. The resultant agglomerated fructose product contained 9 to 12 percent PEG. Five gram, 7/8 inch diameter lozenges were produced with direct compression. Lozenge quality was high with a hardness of over 15 kg and 20 to 30 minute dissolution. Additionally, un ground Krystar 300 crystals were coated with PEG 8000, and ground Krystar 300 crystals were agglomerated with PEG 8000 for use as tablet bases. Lozenges had a break strength of 12 to 25 kg, respectively, when compressed to 9 tons applied pressure. Lozenges dissolved in 20 to 25 minutes and produced 30 ml of saliva.

    Zinc gluconate in PEG-treated fructose was superior in taste to other zinc gluconate products. The mild taste and aftertaste of pure zinc gluconate remained, requiring modest flavor-masking. Several zinc gluconate, fructose, and PEG compositions became tan to light brown in severe aging and thermal tests, suggesting slow degradation of lozenges.

    RBS Pharma zinc gluconate lozenges tested by the Medical Research Council (see Chapter 4.A.2) were outstanding examples of flavor-stable zinc gluconate lozenges. RBS Pharma lozenges had a 44 ZIA value, nearly the highest ZIA value possible for flavor-masked zinc gluconate. The one-gram lozenges were made of fructose, zinc gluconate, and Methocel(r) and were sweetly flavored. Even after storage for five years, no extra bitterness occurred, even though the flavor oil was then absent. However, the generally objectionable bland, chalky zinc gluconate taste and 24-hour aftertaste remained. There is a 1-to-3 order of magnitude reduction in bitterness between zinc gluconate lozenges made with fructose and zinc gluconate lozenges made with any other sweet tablet base after equivalent lozenge aging.

    As only moderate amounts (about 30 percent) of zinc gluconate are available as Zn2+ ions at pH 7.4, a daily ZIA of 100 using 23 mg zinc as zinc gluconate 9 times per day is possible only from lozenges producing little saliva and remaining in the mouth for an extended time (see Chapter 4.A.1).

    The maximum ZIA value for 23-mg zinc flavor-masked zinc gluconate lozenges having a wet granulated fructose and Methocel(r) base is about ZIA 50 when used each 2 hours. Consequently, to obtain a ZIA 100 response with flavor-masked zinc gluconate lozenges, patients would necessarily treat themselves once every hour while awake. Alternately, lozenges with higher zinc gluconate dosages can be developed. Unfortunately, addition of Methocel(r) causes an unpleasant slimy feeling in the mouth because of the high viscosity of the Methocel(r)-saliva mix, resulting in a product of questionable commercial value. Lozenges containing zinc gluconate in a base of crystalline fructose with Methocel(r) binder do not become bitter regardless of time. However, addition of as little as 1 percent sucrose or other sweet carbohydrate is sufficient to cause onset of delayed bitterness.

    Clearly, the only suitable tablet base for zinc gluconate is fructose, which is non-compressible in crystalline form. However, zinc gluconate lozenges could be manufactured using micro-powdered fructose (powdered Krystar(r)). Powdered Krystar(r) contains 2% silica gel as a moisture absorbent and flow enhancer. Powdered Krystar(r) was easily compressed on a hand press to form extremely hard lozenges having a very slow dissolution rate without increased bitterness over time. Lozenges were very hygroscopic. Direct compression of lozenges using powdered fructose is not commercially possible, because of the extreme lightness and fluffiness of the composition, and the extreme amount of dust generated by the process.

    Slugging (precompression of powder, followed with milling to obtain compressible granules) the powdered fructose, re grinding the pellets, and using the ground composition to mix with zinc gluconate and other tablet ingredients appears feasible and perhaps desirable. Addition of nonsoluble wax to fructose may produce a viable tablet base for zinc gluconate lozenges.

    Tableting characteristics of fructose and sorbitol using polyvinylpyrrolidone (PVP) in isopropanol as a binder have been described(9) and might be suitable for this application, but they have not been tested by the author.

    Anethole as Flavor Mask

    When the lozenge base is fructose, zinc gluconate lozenges can be effectively flavor-masked with anethole to eliminate unpalatable taste and aftertaste. Anethole, a highly stable but aromatic flavor oil, is the main constituent of the essential oils of anise, star-anise, and fennel. Anethole is almost totally insoluble in water and cannot chelate Zn2+ ions.

    Anethole is found in beverages, foods, candy, and pharmaceuticals as a flavor- and odor-masking agent. Anethole is also used as a sedative, stimulant, and expectorant in cough mixtures and lozenges. The taste-masking effect of anethole on zinc compounds is strong, long-lasting, and unique. Such parameters allow sustained application of zinc gluconate in the form of a lozenge to the oral and oropharyngeal mucosa with no bitter taste or aftertaste. With the amount of high-quality anethole properly balanced with zinc gluconate in a fructose lozenge, anethole can mask taste and aftertaste of zinc gluconate for over 24 hours. Anethole cannot, however, mask the bitter taste occurring when zinc gluconate is combined with sucrose, dextrose, mannitol, sorbitol, lactose, maltose, xylitol, or various combinations.

    Flavor-masked zinc gluconate lozenges can be prepared by adding 12-16 mg of high purity anethole (Arizole Anethole Extra, by Arizona Chemical Company, Panama City, Florida) plated onto silica gel (Siloid 244FP, by Davidson Chemical, Baltimore, Maryland), with 175 mg zinc gluconate (23 mg zinc) to a 5-gram tablet of pure fructose incorporating PEG 8000 or Methocel(r) as a binder.

    Stability of anethole flavor-mask in fructose was acceptable over a 4-month test period, unless lozenge container remained unsealed. If left unsealed, anethole quickly evaporates, and the lozenge taste eventually becomes bland and chalky but not offensive or bitter in taste. Spray dried flavors or flavor oil incorporated within beta-cyclodextrins were not flavor-stable, as dextrose within those compositions reacted with zinc gluconate causing bitterness.

    The main disadvantages of anethole as a zinc gluconate flavor mask are extreme aromaticity and a distinctive, anesthetic-like taste in the amounts used. Evaporative loss of only 2 or 3 mg anethole is sufficient for loss of flavor mask. Although other flavors can be added, such as eucalyptol and menthol, the primary taste is anethole and is disliked by many taste-testers.

    In the final analysis, anethole flavor-masking of zinc gluconate in fructose lozenges does not produce a product acceptable in taste to everyone, even though technically sound, modestly efficacious lozenges are possible.

    Low ZIA Value for 5-Gram Zinc Gluconate Lozenge

    The most alarming finding about anethole flavor-masked zinc gluconate lozenges is their low ZIA value. Five-gram fructose and PEG lozenges containing 23 mg zinc from zinc gluconate compressed to 9 tons, dissolve in the mouth in 21 minutes, and produce 30 ml saliva, resulting in a daily ZIA 34 value when a lozenge is used every 2 hours while awake (9 t/d). A pleasant taste could be obtained with anethole flavor-masked, 5-gram fructose-based lozenges, or efficacy could be obtained with a slow-dissolving, unflavored, nonsoluble tablet (see chapter 4.A.1). A zinc gluconate lozenge with both high efficacy and flavor appears impossible using direct compression techniques.

    The wet granulation technique used by RBS Pharma to produce the slow-dissolving zinc gluconate lozenges tested by the MRC Common Cold Unit may be the best technique for producing both efficacy and flavor. The RBS Pharma lozenges produced a ZIA value of 44 primarily because lozenges stimulated only two-thirds the saliva produced by 5-gram fructose-based lozenges.

    Search for Efficacy and Pleasant Taste

    Many other zinc compounds were examined for utility in zinc lozenges. Modest amounts of zinc sulfate, zinc oxide, zinc picolinate, zinc ascorbate, and zinc amino acid chelates showed little or no utility against the duration or severity of common colds.

    Several interesting lipophilic compounds were found to be highly cytotoxic by Merluzzi and colleagues,(10) and were not tested by the author. Chelated zinc compounds releasing neutral zinc complexes, including zinc gluconate (releases mainly zinc gluconate-hydroxide at physiologic pH 7.4; see Figure 1), may produce mild cytotoxicity. The objectionable 24-hour aftertaste of zinc gluconate may be evidence of mild cytotoxicity through intra cellular absorption of zinc gluconate-hydroxide.

    Only zinc compounds releasing 100 percent of their zinc as Zn2+ ions at salivary pH through physiologic pH 7.4 are currently viewed as having adequate safety potential for use in zinc lozenges. Of generally regarded as safe (GRAS) compounds, only zinc chloride and zinc acetate have such properties.

    Evaluation of many zinc compounds having a first stability constant of less than or equal to log K1 = 2.0, and particularly zinc compounds having a first stability constant less than or equal to log K1 = 1.0 (zinc chloride, propionate, butyrate, benzoate, formate, acetate and others),(1) were considered, and numerous other experiments were conducted over several years.

    Perhaps the zinc compound most likely viewed by zinc researchers to be beneficial in zinc lozenges is zinc chloride. Zinc chloride has a very low first stability constant (log K1 = 0),(1) but zinc chloride immediately complexes with carbohydrates such as dextrose and sucrose in situ to form brown discolorations on white lozenges. Zinc chloride and all lozenges made with it are extremely hygroscopic. Zinc chloride also has an objectionable, caustic taste, rendering it less than desirable for incorporation in zinc lozenges.

    Although many formulations using these highly unstable zinc compounds appeared useful to shorten common colds, the search ultimately led to zinc acetate, an extremely pungent, sharply flavored, stable, non-hygroscopic zinc compound which in concentrated solutions tastes like vinegar. Patently surprising and unique, when zinc acetate is compounded into sweet, carbohydrate-based lozenges of almost any composition, lozenges have pleasant tastes to the normal palate and are flavor-stable for years.

    Chapter 6 References

    1. Furia TE. Sequestrants in food. In Furia TE ed., CRC Handbook of Food Additives. 2nd ed. West Palm Beach, Fl:CRC Press; 1972:271-294.

    2. Paragraph 170.50 Glycine (aminoacetic acid) in food for human consumption. Code of Federal Regulations Title 21: Food and Drug Administration, Department of Health and Human Services, Parts 170-199, revised April 1, 1990, Office of the Federal Register National Archives and Records Administration:Washington DC.

    3. Ibid.; § 172.320 Amino acids.

    4. Bekendam G. Technical Bulletin: Zinc gluconate lozenges. Akzo Chemie, Deventer, The Netherlands. January 22, 1985.

    5. Acacia. Windholz M, Budavari S, Blumetti RF, et al, eds. The Merck Index. Rahway NJ:Merck & Company. 1983.

    6. Briggs J, Finch P, Matulewicz MC, et al. Complexes of copper(II), calcium, and other metal ions with carbohydrates: Thin-layer igand- exchange chromatography and determination of relative stabilities of complexes. Carbohydrate Research. 1981;97:181-188.

    7. Zarembo JE, Godfrey JC, Godfrey NJ. Zinc(II) in saliva: determination of concentrations produced by different formulations of zinc gluconate lozenges containing common excipients. Journal of Pharmaceutical Sciences. 1992;81:128-130.

    8. U.S. Patent 5,059,419, dated October 22, 1991.

    9. Osberger T. Tableting characteristics of pure crystalline fructose. Pharmaceutical Technology. June 1979.

    10. Merluzzi VJ, Cipriano D, McNeil D, et al. Evaluation of zinc complexes on the replication of rhinovirus 2 in vitro. Research Communications in Chemical Pathology and Pharmacology. 1989;66: 425-440.





    Chapter 7. Zinc Acetate Lozenges as Successor to Zinc Gluconate lozenges

    Executive Summary Chapter 7 describes zinc acetate lozenges as the successor to zinc gluconate lozenges. Zinc acetate is an outstanding source of hydrated Zn2+ ions, as 100 percent of zinc in zinc acetate solutions is available as Zn2+ ion at physiologic pH 7.4. Zinc acetate lozenges are pleasant tasting, and flavor stable for years. The tablet base can be any carbohydrate sweetener such as fructose, sucrose, dextrose, or other directly compressible, sweet carbohydrate pharmaceutical carriers. None complexes with zinc acetate to cause bitterness in compressed tablets.

    Zinc acetate lozenges having ZIA values of up to 280 using 25 mg of zinc can be readily manufactured. Zinc acetate lozenges having a ZIA value of 100 when used 9 times per day can shorten the duration of rhinovirus common colds by an average of 7 days. Lozenges can have any flavor, although preference is given to peppermint. Pharmaceutical characteristics of standard and advanced design lozenges, including Zn2+ ion salivary concentrations, ZIA values by dosage strength, ZIA values and dissolution rates by compressive forces applied, and lozenge taste test results are shown.

    Zinc acetate lozenge compositions are unique, as these lozenges have great potential for efficacy without toxicity or objectionable taste or aftertaste to the normal palate. As zinc acetate lozenges release only Zn2+ ions and no neutrally charged zinc species capable of entering cells, lozenges are completely non-toxic. Zinc acetate lozenges do not have unpleasant tastes or aftertastes typical of zinc gluconate or other highly ionizable zinc compounds. Pleasant-tasting, flavor-stable 5- to 25-mg zinc (zinc acetate) lozenges can be prepared using sucrose, fructose, or dextrose tablet bases without bitterness. When stored in sealed containers, they are flavor-stable for many years. Standard design and advanced design lozenges, their ZIA values, and other characteristics are presented in this chapter.

    Zinc Acetate as Source of Zn2+ Ions

    Although zinc gluconate is the best known source of Zn2+ ions in lozenges for treating common colds, zinc acetate merits special attention. Zinc acetate has chemical properties preferable over zinc gluconate for use in zinc lozenges. For example, zinc acetate dihydrate is 29.7 percent zinc and anhydrous zinc acetate is 35.5 percent zinc, compared with 13.14 percent zinc in zinc gluconate. Only 77.23 mg zinc acetate is needed to provide 23 mg zinc, compared with 175 mg of zinc gluconate. Over 400 grams of zinc acetate will dissolve in a liter of water compared with 100 grams/liter for zinc gluconate. Zinc acetate has a considerably lower stability constant than zinc gluconate (log K1= 1.03 vs. 1.70) under identical laboratory conditions.(1) Zinc acetate releases 100 percent Zn2+ ions as no reasonable complexation occurs between zinc and acetate in solutions up to 20 mMol, at any pH between 2.8 and 7 and, a fortiori, far above (Figure 20).(2) Zinc acetate is 3.33 times as ionizable as zinc gluconate at tissue pH 7.4. Zinc acetate was used in vitro by Korant and co-workers at Du Pont to inhibit replication of rhinoviruses.(3) Zn2+ ion, from zinc acetate, is as antirhinoviral and as protective of mono-layer cells in vitro as interferon.

    Zn2+ from zinc acetate is present at 100%Figure 20. Concentration of Zn2+ ion in the zinc and acetate system by pH. Zinc and acetate are present at 10 mMol. Acetate protonation curves in the presence and absence of zinc were found to be exactly super-imposable. Regardless of pH, Zn2+ ion concentration (log K1=1.0) is essentially 100%, with some zinc acetate+ of a low stability constant (log K1=1.7) possibly forming at higher pH. From data by Hacht and Berthon.(2) and personal communication August 2, 1999.

    It is fully capable of stabilizing cell membranes and closing pores in cells induced by cytolytic agents. The increased availability of Zn2+ ions at pH 7.4 allows Zn2+ ion concentration to be sufficiently high to produce high ZIA values even when used in sugar lozenges producing large amounts of saliva. Therapeutic doses may be astringent but need not be orally irritating. When 5 to 23 mg of zinc from zinc acetate is compounded into 5-gram sugar-based lozenges, lozenges have ZIA values from about 30 to 200 and are flavor-stable and have pleasant tastes.


    Flavor Stability

    Along with a much larger amount of available Zn2+ ion, flavor stability is another extremely important property of zinc acetate as demonstrated over multi-year high temperature, summer storage conditions. For example, zinc acetate directly compressed lozenges, in a base of crystalline fructose and agglomerated sucrose (Mendell's Sugartab(r)) and also containing 14 mg sodium saccharin and peppermint oil retained a pleasant sweet taste and had no objectionable aftertaste after a 3-year storage period in ambient conditions cycling from 120 degrees F. in summer to 30 degrees F. in winter. Similar findings were produced using a tablet base of pure fructose agglomerated with polyethylene glycol 8000, although a color change occurred. In numerous other experiments, zinc acetate compressed lozenges with various carbohydrate bases did not become bitter upon aging or thermal cycling over a 3-year period.

    When a pharmaceutically acceptable carrier is sweet, lozenge taste is good. Zinc acetate lozenges do not become bitter upon aging in the presence of fructose, sucrose, or dextrose. Flavor stability is independent of moisture content: whether lozenges are moist to the touch or dry, flavor is not affected regardless of time. Flavor-stability is an outstanding property of zinc acetate lozenges. Moreover, no discoloration of packaged lozenges has been noted during storage, suggesting high chemical stability.

    Acceptability of zinc acetate in zinc lozenges was completely unexpected, because undiluted zinc acetate has a dreadfully vile taste completely offensive by any standard and much worse than the taste of undiluted zinc gluconate. The acetic acid complex of zinc might be expected to smell and taste like vinegar. Crystals do smell like vinegar, but lozenge compositions are completely devoid of any vinegar smell or taste. Zinc acetate compositions never have the long-lasting and offensive aftertastes typical of zinc gluconate compositions.

    Also completely unexpected was the opposite effect of anethol in zinc acetate lozenges.

    Chapter 7.A. General Lozenge Considerations

    Various carbohydrate tablet bases, flavors, undesirable ingredients, and preliminary flavor-testing experiments are discussed as background for selection of "standard design" and "advanced design" zinc acetate lozenges. Significant differences in flavor, ZIA values, and salivary concentrations of Zn2+ ion resulting from changing only the tablet base are discussed as basis for selecting two basic designs.

    Fructose, Sucrose, and Dextrose as Pharmaceutical Carriers

    Fructose is the sweetest of the natural sugars and is 1.73 times sweeter than sucrose. Fructose is a component of sucrose, a disaccharide, and is an isomer of dextrose, the other component of sucrose. Dextrose is 0.74 times as sweet as sucrose. The stability constant of dextrose for zinc is log K1 = 0.01.(1) Similar exceedingly low values are found for other carbohydrates and zinc, and similar low stability is also expected for sucrose and fructose. Most nutrients seem to decrease absorption of zinc, but sucrose may increase absorption according to animal studies.(4)

    Surprisingly and unexpectedly, fructose does not visibly react, change color, or form bitter compounds with zinc acetate at higher ambient temperatures, as this monosaccharide is a polyhydroxy ketone and is usually considered highly reactive. Fructose is hygroscopic, and relative humidity should be less than 55 percent during production to avoid moisture accumulation.

    By contrast, dextrose, a polyhydroxy aldhyde is normally considered to be an inert monosaccharide. Dextrose reacts with zinc gluconate and other zinc compounds over time to form very bitter complexes, but dextrose does not react with zinc acetate to cause bitterness. Because both acetic acid and gluconic acid are closely related monocarboxylic acids, it is strange they react so differently.

    Commercial Directly Compressible Tablet Bases

    Use of pharmaceutical tablet bases and other pharmaceutical tableting materials suitable to make zinc acetate lozenges are well described in Pharmaceutical Dosages Forms, Volumes 1, 2 and 3.(5) Tablet formulation(6) is well covered as are chewable tablets.(7) Each has application to formulating zinc lozenges. The chapter on directly compressed tablets also has special significance, as properties of tableting ingredients are discussed in detail.(8)

    Mendell's Sugartab(r) is a white, free-flowing storage-stable, inert tablet base of agglomerated sugar containing 90 to 93 percent agglomerated sucrose with the balance being invert sugar. Sugartab(r) has a sweetness value of 1, identical to sucrose. When blended with the active ingredient plus a suitable lubricant and compressed, Sugartab(r) produces moderately hard, nonfriable tablets. Sugartab(r) has good flow characteristics, good compressibility, flavor-masking, low hygroscopicity, chemical stability, noncloying sweetness, a wide range of compatibilities, smooth disintegration, and pleasant aftertaste. Sugartab(r) is a white granular powder having an average particle size of 296 microns.(9) Even though Sugartab(r) is sweeter than Emdex(r) and equivalent in sweetness to Sweetrex(r), zinc acetate lozenges made with Sugartab(r) have a sharp flavor and aftertaste.

    Mendell's Sweetrex(r) is a directly compressible chewable tablet base with a sweetness value of 1, equivalent in sweetness to Sugartab(r) and sucrose. Sweetrex(r) does not contain sucrose. Sweetrex(r) is a blend of 70 percent Emdex(r) and 30 percent Krystar(r) 300 crystalline fructose (A. E. Staley, Decatur, IL). Sweetrex(r) has a demonstrated binding capacity of up to 50 percent active ingredients with no significant loss of compressibility. Sweetrex is claimed by the manufacturer to be ideally suited for the direct compression of chewable tablets since it possesses qualities of cool mouth-feel and is naturally sweet without the incorporation of artificial sweetening agents. Sweetrex(r) is a white granular powder, having an average particle size of 210 microns.(9) Because Sweetrex(r) contains fructose, it is hygroscopic and must be stored at less than 55 percent humidity.

    Mendell's Emdex(r) is known as a dextrate, and complies with the official monograph in National Formulary XVI as the hydrated form. Its sweetness value is 0.74 of sucrose. Emdex(r) is a highly refined product composed almost entirely of free-flowing spray-crystallized porous spheres. Emdex(r) has outstanding fluidity and compressibility recommending it for direct compression techniques to produce lozenges. With Emdex(r) as a lozenge base, glidants are unnecessary, induced die feeding is eliminated, and presses may be operated at maximum speed. Because Emdex(r) is soluble in water, it is commonly used in chewable tablets and lozenges. Emdex(r) has outstanding flow, compressibility, lubricity, non-hygroscopicity, controlled particle size, cool mouth-feel, negative heat of solution, stability to heat and moisture, and other pharmaceutical properties. Microscopic observation reveals remarkably uniform tiny "snowballs" with a high degree of crystallinity. Scanning electron micrographs indicate each spherical granule consists of randomly arranged flat microcrystals bound together by minute amounts of higher saccharides and interspersed with various shaped and sized void spaces. The Drug Master File number is 1195.(9) Emdex(r) is stable and compatible with zinc acetate but not with zinc gluconate.

    Flavors

    Peppermint oil (flavor #113.042, Bell Flavors, Northbrook, Illinois) is recommended as it is sweet, highly acceptable to essentially all patients, and has a menthol effect in the nose without menthol bitterness. Peppermint oil is considered a food product and not a drug. Bell peppermint oil also has proven multi-year stability in directly compressed zinc acetate lozenges.

    Peppermint oil can be directly absorbed into Emdex(r) with high pressure micro fine mists of peppermint oil, and thorough mixing. Peppermint oil can also be dried with silica gel (Siloid(r) 244FP - Davison Chemical, Baltimore, Maryland). Peppermint oil will become dry at a 1:1 ratio with silica gel, but flavor losses occur. Perhaps losses result from retention of peppermint oil by silica gel. For example, lozenges containing 5 mg of peppermint oil sprayed directly into Emdex(r) have a flavor equivalent to lozenges containing 17 mg of peppermint oil platted onto 17 mg of silica gel.

    According to the Code of Federal Regulations, use of amorphous silica gel cannot exceed 2 percent of the finished weight and currently can only be used to encapsulate lemon, distilled lime, orange, peppermint, and spearmint oils.(10,11) Other drying agents are not used because of their bulk and potential for chelating Zn2+ ion either in solid state reactions or solutions.

    Most flavorings can be used in zinc acetate lozenges given a suitable carrier. Eucalyptol, wintergreen, clove, cinnamon, spearmint, cherry, lemon, orange, lime, menthol and various combinations are all possible flavorings. However, some flavor oils are not stable in long-term storage in zinc acetate lozenges and may require costly protection from contact with zinc acetate, evaporation, degradation, and oxidization generally.

    In zinc acetate lozenges, flavors might be stabilized by spray drying with National Starch's N-Lok(r) or other similar modified starches, or flavors might be included within cyclodextrins and/or coated with PEG 8000. Spray-dried flavors must not include acacia (gum arabic) and other zinc-chelating vegetable gums. All spray dry agents, including N-Lok(r), must be tested for Zn2+ ion-chelating ability and stability before use or clinical testing, as none have been tested.

    Plated onto silica gel or sprayed into Emdex(r), menthol and eucalyptol appear stable for at least three years in directly compressed zinc acetate lozenges in sealed bottles.

    Strangely, anethole reacts over time with zinc acetate, but not with zinc gluconate, to produce bitterness, whether it is plated on silica gel or incorporated within cyclodextrins, and anethole should not be used with zinc acetate.

    Undesirable Ingredients

    Zinc acetate compositions for treating common colds must exclude Zn2+ ion-depleting ingredients and other incompatibles. Acacia (gum arabic), alkalis and their carbonates, oxalates, phosphates, sulfides, caustic lime and vegetable decoctions are considered incompatible with zinc acetate.(12)

    Other vegetable gums, anethole, mannitol, sorbitol, super sweeteners, ascorbic acid (vitamin C) citric acid, tartaric acid, other food acids, and lake colors may cause compositions to become flavor unstable, cause a loss of efficacy against common colds, or both and must not be added to zinc acetate lozenges.

    Overemphasizing the necessity to avoid inadvertent chelation of Zn2+ ions by addition of chelating ingredients is not possible.

    A good policy is to add no water-soluble ingredients other than simple sugars to lozenges. A better policy is to use only the ingredients described for standard design lozenges, while the best policy is to use only the ingredients described for advanced design lozenges. (See sections B and C later in this chapter.)

    Preliminary Examples of Flavor-Stable, Pleasant-Tasting Zinc Acetate Lozenges

    Extensive multi-year flavor-testing research led to the development of numerous basic formulations and variants. Several preliminary formulations are discussed next as being representative of the general theme of incorporating zinc acetate in sucrose, fructose, and dextrose lozenges. Even though these lozenge formulations appear similar, their performances are significantly different. Differences in ZIA values are dependent upon tablet bases, zinc content, sweetness, compressive forces used in lozenge manufacture and physiologic characteristics of the user. Consequently, it is imperative that changes not be made to zinc acetate lozenge design once comprehensive tests with a given formulation -- including compressive forces -- are completed: clinical results are dependent upon too many factors to change any variable, even by a small amount.

    To make 5-gram Sweetrex(r)-based lozenges containing 23 mg zinc, mix 77.2 mg zinc acetate dihydrate USP, 0.5 to 5.0 mg peppermint oil (sprayed onto Sweetrex(r)), 125 mg glyceryl monostearate, and sufficient Sweetrex(r) to make a 5-gram lozenge and compress tablets.

    To make 5-gram Sugartab(r) and fructose-based lozenges containing 23 mg zinc, mix 77.2 mg zinc acetate dihydrate USP, 0.5 to 5.0 mg peppermint oil (sprayed onto Sugartab(r)), 125 mg glyceryl monostearate, about 2450 mg Sugartab(r), and sufficient crystalline fructose to make a 5-gram lozenge and compress tablets.

    To make a 5-gram Emdex(r)-based directly compressible tablet containing 23 mg zinc, mix 77.2 mg zinc acetate dihydrate USP, 0.5 to 5.0 mg peppermint oil (sprayed onto Emdex(r)), 1 to 10 mg sodium saccharin, 125 mg glyceryl monostearate, and sufficient Emdex(r) to make a 5-gram lozenge and compress tablets.

    Compositions are thermally, chemically, and flavor-stable, having a pleasant taste and aftertaste. Glyceryl monostearate lubricant is added to mixtures late in the mixing procedure in the normal fashion. Mixtures are always prepared immediately before compression and not stored in a premixed manner to preclude moisture pickup.

    Glyceryl monostearate is always used at 2.5% of total lozenge weight.

    Tablet Presses

    All research tablet press data, such as compressive forces applied and resultant information found in Handbook for Curing the Common Cold were developed using an instrumented, static hand press capable of 10 tons applied force. Rotary presses have been used to manufacture sample, and commercial lozenges using the formulations given.

    For commercial purposes, instrumented tableting equipment such as the Korsch Pharmapress 230, 250, and 350 presses (Korsch Tableting, Somerville, New Jersey) can show the exact pressures and precompression needed to maintain a stable and uniform ZIA. Other presses, including the Manesty D3B and the Stokes RD-4, having adequate capacity can be used.

    Five-gram zinc acetate lozenges are prepared by direct compression. Lozenges are compressed using 7/8 inch diameter tooling to about 6 to 10 tons applied pressure with precompression. Five-gram lozenges are 0.410 inch thick at the crown and 0.290 inches thick at the edges using standard concave tooling. Uncompressed column height of 7/8 inch lozenges is 11/16 inch. Three and one-half gram, 3/4 inch diameter lozenges are 0.385 inches thick at the crown and 0.275 inches thick at the edge using standard concave tooling. Uncompressed column height of 3/4 inch lozenges is 0.70 inch.

    Introducing mMolT

    In previous chapters, salivary Zn2+ ion concentration and ZIA were calculated excluding the weight of the non-soluble or soluble tablet. As the tablet weights of the two most efficacious studies were low (0.66 and 1 gram), significance of the omission was negligible. Even with omission, aqueous ion concentration remained inaccurately represented because water in saliva contains other salivary constituents.

    As the lozenge weight is increased in this chapter to between 3.5 and 5 grams, consideration of the lozenge becomes more important. Better estimates of the concentration and dispersion of Zn2+ ion in the mixture of saliva and the dissolved lozenge constituents are suggested to be obtained by including the lozenge in calculations of Zn2+ ion total molality (mMolT) and ZIA.

    Lozenges studied in this chapter have a specific gravity of 1.5. Consequently, the saliva dissolved lozenge weights are modified accordingly to obtain the mixture volume in milliliters. Reflecting the specific gravity differences, 1.67 grams are subtracted from saliva weights during the calculation of mMolT and ZIA to represent the volume of the mixture of saliva and 5-gram lozenges. Tables in this chapter showing grams of saliva are unmodified and represent actual weights of the saliva/lozenge mixtures.

    Taste Tests, Zn2+ Ion Molar Concentration, and ZIA Values of Preliminary Zinc Acetate Lozenges

    Flavor tests show different tablet bases strongly affect Zn2+ ion concentration, ZIA values, and flavor of lozenges. With no changes other than tablet base, major variations in ZIA values and lesser variations in Zn2+ ion concentration are readily observed. The formulation with the highest ZIA value was also the formulation perceived by the taste testers to have the best taste and aftertaste, although it had an intermediate Zn2+ ion concentration. Too much lozenge sweetness as well as insufficient sweetness can have detrimental effects on ZIA values by stimulating saliva production.

    For purposes of the following preliminary flavor research, all tested lozenges contained 77.2 mg zinc acetate (23 mg zinc), 17 mg peppermint oil plated onto an equal amount of silica gel, and 125 mg glyceryl monostearate. All ZIA calculations used an available Zn2+ ion fraction of 100 percent for zinc acetate, 9 doses per day and 23 mg zinc per lozenge.

    Break strength of the Sugartab(r) and fructose, Sweetrex(r), and Emdex(r) lozenges was 6, 12 and 22 kilograms, respectively, at 9 to 10 tons applied force.

    Sodium saccharin may be added to Emdex(r)-based lozenges to increase sweetness, but addition requires recalculation of ZIA values.

    Flavor testing is a highly subjective process not amenable to technical evaluation except by use of an expert taste-panel. The same taste-testers tasting previous lozenges described in Chapter 4 also tasted samples of the zinc acetate lozenges described in this chapter. Comparison between compositions on an individual basis is possible. Tester #1, who repeated tests, showed reasonable agreement between values with each composition. Tester #2 had considerably more saliva generation with each composition than the other testers and consistently produced the lowest ZIA value. Every effort was made to be as consistent as possible in taste evaluation.

    However, on rare occasions flavor testers reported inconsistent flavor observations with lozenges having a mildly objectionable aftertaste.

    Table 11. Characteristics for preliminary 23-mg zinc (zinc acetate) 5-gram lozenges having different directly compressible bases.

    ______________________________________________________________________
    
    Research 	Flavor	ZIA	Zn2+    Dissolution  Doses    Saliva 
    lozenge		Rating	value 	mMolT   time (min)   /day     (grams)
    ______________________________________________________________________
    
    100% Sweetrex(r) 
    lozenge base
    ______________________________________________________________________
    Tester 1 
    (1st test)	  10	134	11.9	25.0		9	31.5
    Tester 1 
    (2nd test)	  10	174	12.9	30.0		9	29.2 
    Tester 2	  10	102	 6.5	35.0		9	56.3
    Tester 3	  10	243      9.6	56.0	        9	38.5
    Tester 4 	  10	205	12.7	36.0	        9	29.7
    Average + s.e.m.  10	171+25	10.7	36.4	        9	37.0
    _______________________________________________________________________
    
    100% Emdex(r) 
    lozenge base
    _______________________________________________________________________
    
    Tester 1 
    (1st test)	    7	132	 9.7	 30.0	        9	38.0
    Tester 1 
    (2nd test)          7	153	10.0	 34.0	        9	37.2
    Tester 2	    8	109      5.4	 45.0	        9	67.8
    Tester 3	    8	172      6.4	 60.0	        9	57.3
    Tester 4    	    9	175      9.9	 39.0	        9	37.3
    Average + s.e.m.    8	148+12.5 8.3	 41.6	        9 	47.5 
    _______________________________________________________________________
    
    50% Fructose and 50% Sugartab(r) lozenge base
    _______________________________________________________________________
    Tester 1 
    (1st test)	   10	128	14.9	 19	        9	25.4
    Tester 1 
    (2nd test)
    Tester 2	   10	124	12.5	 22	        9	30.0	
    Tester 3   	    8    54      7.5   	 16  	        9	48.8 
    Tester 3	    9	135	17.7	 17	        9	21.7
    Tester 4	    8	112	14.7	 17	        9	25.8
    Average + s.e.m.    9	111+14  13.5	 18.2	        9	30.3
    _______________________________________________________________________
    

    On a scale of 0 to 10 (with 0 being dreadfully bitter, 5 being acceptable but not necessarily pleasant, and 10 being as pleasant as candy or no taste sensation other than astringency) the lozenges are flavor rated as shown in Table 11. The Sweetrex(r) (dextrose and fructose) lozenges were perceived as having the best taste. Without added saccharin, the Emdex(r) lozenges were perceived as being bland in taste and not as pleasant-tasting as the other two preliminary samples. As lozenge sweetness was borderline using Emdex(r) and no saccharin, more peppermint flavor was needed. Sugartab(r)/fructose lozenges were perceived as being the sweetest and the sharpest tasting of the preliminary lozenges.

    Sucrose within Sugartab(r) may cause the sharp flavor perceived as a mild burning sensation in the throat or as a slight throat irritation. Because of the oral burning sensation perceived by the taste testers, neither Sugartab(r) nor sucrose were evaluated past preliminary tests. Sharpness in flavor and oral irritation did not seem to appear in zinc acetate lozenges without sucrose or Sugartab(r). None of the preliminary lozenge samples tasted bitter.

    Sugartab(r)/fructose lozenges tended to produce less saliva and dissolve considerably faster than lozenges having a base of Sweetrex(r) or Emdex(r). The Emdex(r)-based lozenges required the most time to dissolve and consistently produced the most saliva. Lozenges made with Sweetrex(r) had intermediate dissolution times and saliva generation characteristics, and the highest ZIA values. Dissolution times for Sweetrex(r) and Emdex(r) lozenges were reasonably comparable.

    Zinc acetate lozenges having a Sweetrex(r) base had the highest ZIA value at 171+25, and were also perceived as tasting best. Zn2+ ion concentration for the Sweetrex(r)-based lozenge was 107 times the amount needed for in vitro antirhinoviral activity. The Sugartab(r)-fructose based zinc acetate lozenges had the highest Zn2+ ion concentration (135 times antirhinoviral) but the lowest ZIA value at 111+14.6 primarily because lozenges quickly dissolved. The Emdex(r) based lozenges had the most uniform ZIA values (148+12.5) but lowest Zn2+ ion molar concentration (83 times antirhinoviral).

    Average ZIA value variation of 60 points between the tablet bases is important and demonstrates the necessity for careful ZIA testing in human beings.

    Picking (lozenge ingredients sticking to punches) in some Sugartab(r)-fructose based lozenges was solved with increased drying and incorporation of additional glyceryl monostearate. None of the preliminary lozenges capped or showed tendency to internal capping or had any other undesirable physical attributes. All physical handling and flowing properties of mixed powders were within the normal range for direct compression.

    General Lozenge Design Considerations for Maximizing ZIA

    Variables affecting ZIA factors of zinc acetate lozenges (Zn2+ ion concentration and time applied) and product acceptability include the dosage strength, lozenge diameter, lozenge shape, lozenge weight, compression pressure, mass-to-surface area ratio, and porosity. Lower dosage results in taste improvement and little if any decrease in saliva production, while larger dosages result in increased efficacy and reduced saliva generation. Equivalent dosages in larger and smaller lozenges of the same tablet base will not have equivalent ZIA values. Identical formulas in larger and smaller lozenges will not have proportionately identical ZIA values. Smaller diameter lozenges allow higher applied pressure per square inch, increased hardness, and dissolution times, perhaps resulting in improved patient acceptance. Larger diameter reduces applied pressure, reduces hardness, and reduces dissolution times. Lozenges over 7/8 inch diameter have decreased patient acceptance. Spherical shape (lowest surface area) minimizes dissolution rate; thin wafers (higher surface area) increase dissolution rates. Higher weight allows longer dissolution time and lower Zn2+ ion concentration. Less weight economizes on raw material and finished product costs. High pressure minimizes dissolution rate, while low pressure increases dissolution rate. Less porous lozenges decrease surface area and decrease dissolution time, while more porous lozenges increase surface area and lower dissolution time.

    The many variables affecting ZIA demonstrate that unique compositions must be tested in human beings to determine their average ZIA values. Generally, 5/8 to 3/4 inch diameter, standard concave tooling produces the most favorable results, and the greatest patient acceptance.

    7.B. - Standard Design Lozenges

    After considerable research by the present author, a standard design for 5-gram zinc acetate lozenges can be recommended, although advanced 3.5- to 5-gram designs based upon the standard design are also presented and are preferred.

    Standard 23-mg zinc lozenges having a ZIA value of 148+12.5 when used 9 times per day, are compounded with 77.2 mg zinc acetate dihydrate USP (Heico Chemicals, Delaware Gap, Pennsylvania) in a 7/8-inch diameter, 5-gram directly compressible dextrose (Emdex(r) - Edward Mendell Co., Carmel, New York) base. The preferred flavoring is peppermint oil (0.5 to 5 mg). The most economic application of peppermint oil is by direct spraying and thorough mixing of peppermint oil with Emdex(r), as flavor oil requirements are reduced by two-thirds compared with platting peppermint oil onto silica gel. Sodium saccharin (1 to 10 mg), menthol (1 to 10 mg), and 125 mg glyceryl monostearate are used as needed. The first stability constant for zinc and dextrose is log K1 = 0.01, showing essentially complete lack of stability.(13) Binders, lake colors, and ionic additives (other than chemically insignificant amounts of sodium saccharin) are not added to preclude inadvertent zinc chelation.

    When sufficiently hard throughout (about 6 to 10 tons applied pressure with precompression), these lozenges produce 47.5 grams saliva and dissolve in about 41.6 minutes. Resultant salivary pH is 5.5 to 6, and salivary Zn2+ ion concentration is 8.3 mMolT. Zn2+ ion concentration is slightly greater than the concentration used in the successful trial in 1984 by Eby and co-workers.

    Zinc acetate lozenges taste pleasant but are astringent, with astringency increasing with increased zinc acetate content. Strong flavoring and sweetness stimulate saliva flow and reduce lozenge ZIA values, while increases in zinc increase astringency and reduce saliva production. In standard design lozenges, least cost, best taste, and maximum ZIA values occur in lozenges having minimal sweetness and flavor.

    The standard lozenge design suggested relies upon Emdex(r) as a tablet-base in preference to other bases because data as to the very low stability constant exists for zinc and dextrose, absolutely eliminating chelation by the tablet base as a source of lozenge failure.

    Comparison of Zinc Gluconate and Zinc Acetate in Identical Tablet Bases

    Because zinc acetate releases 3.33 times more Zn2+ ion than zinc gluconate at physiologic pH 7.4, much more latitude is available using zinc acetate in the design of high ZIA lozenges. Standard design zinc acetate lozenges with an Emdex(r) base producing an average ZIA value of 148+12.5 can be expected to perform well against common colds in essentially all patients. A favorable response with zinc acetate lozenges could even be expected in patients like Tester #2 who produced very large amounts of saliva. Had zinc gluconate -- rather than zinc acetate -- been used in the standard design Emdex(r) base and tested by Tester #2, the value would have been ZIA 33 rather than 109. Limited efficacy against colds in Tester #2 may be theorized to have then resulted.

    Medicinal Additives

    After full development of the basic zinc acetate common cold lozenge and after considerable clinical experience has been gathered in the future, it may be possible and desirable to incorporate one or more medicinal additives as long as they do not chelate or bind Zinc2+ ions at pH 7.4. A wide variety of ingredients to accomplish specific tasks might be incorporated within the lozenges as shown in Table 12.

    ________________________________________________________________________

    Table 12. Medicinal ingredients for incorporation into common cold lozenges

    _________________________________________________________________________
    
    		 	anesthetics, such as lidocaine
    		 	other antiviral agents
    		 	antimycoplasmal agents
    		 	anti-inflammatory agents
    		 	interferon
    	 		antibiotics
    	 		nasal decongestants 
    	 		antihistamines
    		 	antinausea agents
    		 	analgesics
    		 	cough relievers
    	 		waxes 
    _________________________________________________________________________
    

    Medicinal additives may be directly incorporated within compositions if chemically nonreactive with zinc acetate in solution between salivary and physiologic pH 7.4 and if stable in solid state reactions in thermal stresses and multi-year lozenge storage tests. Micro-encapsulation within insoluble and noncrushable membranes will be required for certain medicinal additives. A time-release capability will be necessary for ingredients interfering with release of Zn2+ ions or adversely affecting taste. Time release may be activated by low stomach pH. Inclusion of medicinal additives within beta-cyclodextrins within insoluble microcapsules might be justified.

    Chapter 7.C. - Advanced Design Lozenges

    Development of an advanced design zinc acetate lozenge was suggested because it may be preferable to have a smaller lozenge than the standard 7/8 inch standard design or a sweeter lozenge without saccharin or a less astringent, less potent lozenge. Table 13 shows that 3/4-inch 3.5-gram lozenges produce a higher

    Medicinal additives may be directly incorporated within compositions if chemically nonreactive with zinc acetate in solution between salivary and physiologic pH 7.4 and if stable in solid state reactions in thermal stresses and multi-year lozenge storage tests. Micro-encapsulation within insoluble and noncrushable membranes will be required for certain medicinal additives. A time-release capability will be necessary for ingredients interfering with release of Zn2+ ions or adversely affecting taste. Time release may be activated by low stomach pH. Inclusion of medicinal additives within beta-cyclodextrins within insoluble microcapsules might be justified. ion concentration than 5.0 gram lozenges but results in lower ZIA values. The higher mMol concentration of the 3.5-gram lozenges is closer to the original 1984 Eby and co-workers' 7.4 Zn2+ ion mMol concentration, but the heavier 5.0-gram lozenges are considerably closer in ZIA value to the original 1984 Eby and co-worker lozenges and are less astringent due to lower Zn2+ ion concentration.

    Mendell's Sweetrex(r) (70 percent Emdex(r) and 30 percent crystalline fructose) is used as the tablet base for all advanced design zinc acetate lozenges. Use of Sweetrex(r) results in a higher lozenge ZIA value, less variation in s.e.m., and sweeter lozenges than Emdex(r)-based lozenges. Sweetrex(r)-based lozenges do not need added saccharin or flavor oils to have an acceptable taste, unless the weight ratio of zinc to Sweetrex is above 1:200.

    Table 13. Advanced design 15 mg zinc (zinc acetate) lozenge characteristics (3.5 and 5.0 gram)

    _________________________________________________________________
    
    Research      Flavor	ZIA 	Zn2+ ion  Dissolution Dose Saliva
    Lozenge	      rating		mMolvT	  Time (min)
    __________________________________________________________________
    
    3/4 inch diameter - 3.5 gram lozenges
    
    Tester 1 	10	129	  7.7	  37.0	      9	    31.0
    Tester 1	10	102	  7.8	  29.0	      9	    30.7
    Tester 2	10	 51	  6.3	  18.0	      9	    37.7
    Tester 3	10	 68	  5.2	  29.0	      9	    45.7
    Tester 4	10	 59	  6.8	  19.0	      9	    34.9
    Average + sem	10	 82+14.   6.8	  26.4	      9	    36.0
    
    7/8 inch diameter - 5 gram lozenges
    
    Tester 1 	10	109	  6.0	  40.0	      9	    39.9
    Tester 1	10	116	  6.2	  42.0	      9	    39.2
    Tester 2	10	 73	  4.5	  36.0	      9	    52.9
    Tester 3	10	 95	  5.0	  42.0	      9	    47.9
    Tester 4	10	 75	  5.6	  30.0	      9	    43.2
    Average + sem	10	 94+8.7	  5.5	  38.0	      9	    44.6
    __________________________________________________________________
    

    Fructose is an isomer of dextrose and is believed upon evidence of equivalent efficacy to have the same stability constant for zinc as dextrose.

    Both 3/4- and 7/8-inch lozenges contained 50.3 mg zinc acetate dihydrate (15 mg zinc), 125 mg glyceryl monostearate , with no added sweeteners or flavors. A 9-ton compressive force was applied. Lozenge taste is pleasantly sweet, and the lozenges are flavor-stable for years. Advanced design lozenges are not particularly hygroscopic, and lozenges left on counter-tops for months in air-conditioned rooms remain dry.

    The disadvantages of Sweetrex(r) include (a) it is hygroscopic until tableted, (b) it is more expensive than Emdex(r) (unless Emdex(r) and fructose are mixed on site), and (c) it runs slower than Emdex(r) in most tablet presses.

    Effect of Compressive Force on Lozenge Dissolution Rate

    Advanced design 15-mg zinc 5-gram lozenges (Sweetrex(r) tablet base with 125 mg glyceryl monostearate and no other ingredients) were tested for effects of compressive forces upon aqueous dissolution time. Results of flowing water bath tests at 37 degrees Celsius were compared with oral dissolution rates for identical lozenges. The results are shown in Figure 21. Above two tons of applied force, lozenge dissolution time in the water bath tester hardly increased. Lozenges compressed with less than 4 tons of applied force did not have smooth dissolution characteristics. Those lozenges had a pitted surface appearance, and considerable variation in dissolution rate. Lozenges compressed from 6 to 10 tons have smooth lozenge dissolution surfaces, and dissolve in a uniform manner.

    Effect of compressive force upon dissolution times Figure 21. Effect of compressive force upon dissolution times.

    In oral dissolution tests of lozenges, effects of salivary enzymes and resistance to crumbling by partially dissolved lozenges are major determining factors in lozenge dissolution rates. Using 1 ton of compression, lozenge surface was rough, and intact grains of tablet base floated into the saliva, resulting in a gritty oral sensation. Lozenges tended to crumble from the beginning. Using 2 tons of compression, lozenges retained their rough surface texture but were not gritty and started to crumble 4 to 5 minutes before totally dissolving. As compressive forces were increased from 1 to 6 tons, the dissolution times rapidly increased. With 6 tons of compression, lozenges had a smooth surface and uniformly dissolved to thin wafers. The nearly dissolved thin wafers tended to break about 1 minute before lozenges were totally dissolved. At 10 tons of compression, lozenges dissolved even more uniformly, had a smoother surface texture, and did not crumble or crack at all.

    Figure 21 shows the importance of conducting oral dissolution tests to confirm and extend dissolution time data gathered from water bath testing. If reliance upon water bath tests were solely used, serious errors in the determination of oral dissolution rate and ZIA values would occur. These results appear representative of all advanced design lozenges, regardless of zinc content.

    Effect of Compressive Force on ZIA

    Compressive forces are also an important determinant of lozenge ZIA values. Figure 22 shows the effect of compressive force upon ZIA values of advanced design 15-mg zinc 5-gram lozenges. A three-fold difference in ZIA value results between one and six tons of compressive forces, at ZIA 29 and 92, respectively.

    Effect of compressive force on ZIA valuesFigure 22. Effect of Compressive Force on ZIA values.

    No difference in ZIA value results with compressive forces between 6 and 10 tons. Lack of difference in ZIA values throughout the 6- to 10-ton range suggests compressive force variations within the 6- to 10-ton range in commercial operations will have essentially no effect upon lozenge utility or quality. These results appear representative of all advanced design lozenges, regardless of zinc content.

    Determination of Recommended Dosage Strength

    Determining the amount of zinc acetate in advanced design lozenges necessary to obtain the same ZIA and mMol Zn2+ ion concentration as was present in the original 1984 zinc gluconate lozenges is desirable. Experimental lozenges contained varying amounts of zinc acetate and Sweetrex(r) lubricated with 50 mg glyceryl monostearate . The total tablet weight was held at 5.00 grams. The compressive force was 9.0 tons.

    Effect of zinc content on ZIA and zinc ion mMolT Figure 23. Effect of zinc content on ZIA and Zn2+ ion mMolT concentration.

    From Table 10 of Chapter 5, the original 1984 lozenges are observed to have produced a ZIA value of 100 and a salivary Zn2+ ion concentration of 7.4 mMol, while the less successful MRC lozenges produced a ZIA value of 43.9 and a 5.0 mMol Zn2+ ion concentration.

    From Figure 23 and Table 14, it is clearly shown that 18-mg zinc (zinc acetate) lozenges produce a ZIA value of 108.6 and a salivary Zn2+ ion mMolT concentration of 6.0. Lozenges containing 20 mg zinc produce a ZIA value of 138.4 and a Zn2+ ion concentration of 7.5. Consequently, both ZIA 100 and a 7.4 mMolT Zn2+ ion concentration do not occur together using the 5-gram Sweetrex(r) base.

    Relationship of lozenge zinc content to saliva production Figure 24. Relationship of lozenge zinc content to saliva production.

    ZIA values and mMolT concentration of Zn2+ ions increase at a faster rate than expected from increases of zinc acetate in lozenges (see Figure 23). Non-linearity suggests factors other than lozenge zinc content play a larger role in efficacy of zinc lozenges than previously realized, and consideration of non-linearity is required in future studies. Preliminary evaluation of 25 mg zinc lozenges shows them them to have a ZIA value of 280 and a salivary Zn2+ ion concentration of 14 mMolT.

    Table 14. Average zinc content, ZIA, Zn2+ ion concentration, saliva production, and lozenge duration from zinc acetate lozenges.

    ________________________________________________________________________
    
    Zinc	     ZIA + 	   mMolT	    Saliva           Dissolution
    (mg)	     s.e.m	   Zn2+ ion          (g)	     Time (min)
    ________________________________________________________________________
    
     0	   0.0 +  0	    0.0	            46.68 	 	34.0
     5	  27.6    5	    1.7	            46.66	 	35.8
    10	  54.3 + 12	    3.2	            50.12		38.0
    15	  92.0 + 10	    5.4	            44.60		38.0
    18	 108.6 + 22	    6.0	            47.80		40.2
    20	 138.4 + 29	    7.5	            42.90		41.2
    23	 185.2 + 27	    9.9	            37.28		41.4
    ________________________________________________________________________
    

    Table 14 and Figure 24 show saliva production falling by 20 to 25 percent as zinc content is increased, demonstrating the effect of Zn2+ ion as an oral salivary astringent and drying agent.

    Evaluation of dissolution time data shown in Table 14 and Figure 25 indicates increases in zinc content increase lozenge dissolution times. Increases in dissolution times result from lower saliva generation and may also show the effect of minor decreases in sweetness from larger amounts of zinc acetate. If sweetness is artificially increased with saccharin or sweet flavorings, dissolution times are reduced.

    Effect of lozenge zinc content on dissolution rate of lozenges Figure 25. Effect of lozenge zinc content on dissolution rate of lozenges.

    Taken together, the effects of saliva reduction and increases in dissolution times explain non-linear increases in ZIA and Zn2+ ion concentration from linear increases of zinc acetate in lozenges.

    The concept of ZIA values as the determinant of efficacy appears reasonable, but the ZIA concept remains to be proved. Therefore, the recommended formulation is in the range from 15 to 23 mg zinc (50.37 to 77.2 mg zinc acetate dihydrate USP) in a 5-gram Sweetrex(r)-based lozenge, lubricated with 125 mg glyceryl monostearate, compressed at between 6 and 10 tons with precompression. Theoretically, lozenges will have a ZIA of 92 and a 5.4 mMolT Zn2+ ion concentration, and ZIA of 185 and 9.9 mMolT Zn2+ ion concentration, respectively.

    Effect of Force Applied on Lozenge Thickness

    Compressive force has an obvious effect upon lozenge thickness. ZIA has been shown to be related to the compressive forces applied. Therefore compressive forces and ZIA are related when measurements are taken using the same equipment. The effect of compressive force in tons of applied force compared to lozenge thickness is shown in Figure 26 using the author's static press. Lozenges were standard convex, 7/8-inch diameter, 5-gram, advanced design zinc acetate lozenges. Uncompressed column height was 0.685 inches.

    Effect of compressive force upon lozenge thickness Figure 26. Effect of compressive force upon lozenge thickness.

    The thickness data in Figure 26 are not directly applicable to the determination of forces used, or to the determination of ZIA on equipment other than the author's equipment. However, the first differential of lozenge thickness is applicable to determining the effect of added pressure with any equipment. To maximize ZIA, applied forces must be over 6 tons (from Figure 22). Decreasing differences in thickness from 1-ton incremental forces applied, as shown in Figure 26, suggest comparison to lozenges made using 10 tons of applied force is better with lozenges made at pressures higher than 6 tons. Perhaps lozenges made using 8 tons of applied force produce -- for practical purposes -- identical ZIA values to lozenges made at 10 tons of applied force.

    ZIA values and mMolT concentration of Zn2+ ions increase at a faster rate than expected from increases of zinc acetate in lozenges (see Figure 23). Non-linearity suggests factors other than lozenge zinc content play a larger role in efficacy. From the appearance of the low slope of the curve at 8 tons of applied force, one may reasonable conclude 10 tons is excessive pressure.

    7.D. - Sources of Lozenge Components

    All components of zinc acetate lozenges are standard pharmaceutical items with well-established records in the pharmaceutical industry. However, no record of use of zinc acetate in pharmaceuticals other than in dental preparations has been found. Additional information about zinc acetate USP is found in Chapter 8, Zinc Biochemistry. Sources for zinc acetate lozenge components for standard and advanced design lozenges are shown in Table 15.

    Cost of ingredients for standard design 23 mg zinc, 5-gram ZIA 148 lozenges is one cent per lozenge. Tablet base (Emdex(r)) contributes 71 percent or more of the total cost of the standard lozenge. Of the total ingredient costs, zinc acetate contributes about 6 percent, and peppermint flavor contributes up to 21 percent.

    Cost of ingredients for advanced design 20-mg zinc 5-gram ZIA 138 lozenges is about 0.7 cents per lozenge, when Emdex(r) is mixed with Krystar(r) 300 crystalline fructose from A. E. Staley on site.

    Table 15. Source and cost of zinc acetate lozenge ingredients.

    _____________________________________________________________________
    Ingredient			Source				  $/kg
    _____________________________________________________________________
    Zinc acetate dihydrate USP	Heico Chemical, Delaware Gap, PA  8.36
    
    Emdex(r)			Edward Mendell, Carmel, NY	  1.53*
    
    Sweetrex(r)  			Edward Mendell, Carmel, NY	  2.48#
    
    Fructose - Krystar(r) 300 	A. E. Staley, Decatur, IL 	  0.77*
    
    Peppermint oil (Bell 113.042)   Bell Flavors, Northbrook, IL	108.46
    
    Silica gel (Syloid(r) 244FP)    Davidson Chem., Baltimore, MD  	  5.13
    
    Sodium saccharin Syncal(r)SDS   PMC Specialties, Cincinnati, OH	  2.20
    
    glyceryl monostearate     
    
    	* in truckloads
    	# currently in 100 kilogram drums only

    No considered price estimate for finished, packaged, ready-to-ship lozenges is presented as too many variables contribute. Rough estimates of total factory costs are in the $0.25 to $1.50 range for a package of 24 lozenges. The price of lozenge ingredients is very low, resulting in a feasible common cold treatment having wide appeal to price-conscious consumers.

    7.E. - Other Comments

    The purpose of this chapter has been to present zinc acetate lozenges as the successor to zinc gluconate lozenges in the treatment and cure for common colds. Additionally, different types of analyses required to obtain reliable results using off-the-shelf pharmaceutical ingredients have been demonstrated. The present research does not mean other zinc compounds, formulations, or lozenge tablet bases have been or should be excluded from consideration.

    Other Formulations

    Although not all possible formulations were tested, many other zinc compounds and tablet bases were evaluated before development of the preliminary lozenges presented in the first part of this chapter. Favored alternatives to the 30 percent fructose and 70 percent Emdex(r) base formulation is increased fructose in the base. Ratios as high as 50:50 have been used, with improvement in lozenges flavor.

    Many of the other formulations were rejected for further study or presentation as they produced objectionable tastes and aftertastes and/or soft, quickly dissolving, or capped tablets. Some showed a tendency towards minor internal capping at the high static pressures applied (6 to 10 tons). Although they usually showed no outward signs of capping and appeared highly usable, capping became evident in these rejects only during break-strength and dissolution testing. Lozenges having a directly compressible lactose base were quite elegant but were insufficiently sweet without addition of much saccharin.

    Addition of non-soluble waxes has been suggested to help maintain a slow and perhaps more uniform lozenge dissolution rate than can be obtained by reliance upon compression alone. However, such testing has not been conducted, because a primary focus of the research is to keep the total number of ingredients in the lozenges to a minimum, and because maintaining natural sweetness with minimum bulk and oral residue is a priority. This is not to say addition of wax is ill-advised, but rather that wax has not been added at this time. Wax and crystalline fructose tablet bases may have highly desirable features including the potential for reduced size while retaining a high ZIA value.

    Advanced design zinc acetate lozenges are the simplest zinc compositions studied and are also the most pleasant tasting without addition of extra sweeteners or flavors. If peppermint oil is added, the amount should be kept low, perhaps at 5 mg per lozenge. Saccharin and other additives should never be added to advanced design lozenges.

    Hard-boiled sweets containing pharmaceutically active amounts of zinc acetate usually have an unpleasant metallic taste, can be unpleasantly astringent, and often "set teeth on edge", while otherwise identical compacts (made at room temperature) usually have excellent taste parameters previously described.

    Eliminating Astringency from Zinc Lozenges

    Perhaps the best indicator of the presence of Zn2+ ions, without complex technical analysis, are the presence of astringency and precipitated salivary proteins in expectorated saliva containing residue from a zinc lozenge. However, astringency at salivary pH 5 to 6 does not guarantee equivalent availability of Zn2+ ions at tissue pH 7.4, as was demonstrated with the zinc gluconate-glycine lozenges (see Chapter 4.C.3.).

    ZIA values and mMolT concentration of Zn2+ ions increase at a faster rate than expected from increases of zinc acetate in lozenges (see Figure 23). Non-linearity suggests factors other than lozenge zinc content play a larger role in efficacyLarge amounts of Zn2+ ions (over 50 mg zinc from zinc acetate) in 5-gram lozenges are very astringent and have extremely high ZIA values. Such dosage strength is usually unnecessary, and can result in uncomfortable astringency, oral irritation, and palpable protein precipitates in saliva. Zinc acetate 5-gram sugar lozenges (5 to 25 mg zinc) produce none-to-moderate astringency; however, this astringency is not considered unpleasant or irritating by most patients. Indeed, to most patients astringency is welcome, prompting such comments as, "They really clean my mouth."

    ZIA values and mMolT concentration of Zn2+ ions increase at a faster rate than expected from increases of zinc acetate in lozenges (see Figure 23). Non-linearity suggests factors other than lozenge zinc content play a larger role in efficacyAddition of sweet flavor oils, such as peppermint, can minimize the effects of astringency by increasing saliva production, albeit with possible resultant reduction in lozenge ZIA values.

    ZIA values and mMolT concentration of Zn2+ ions increase at a faster rate than expected from increases of zinc acetate in lozenges (see Figure 23). Non-linearity suggests factors other than lozenge zinc content play a larger role in efficacyZinc lozenges with negatively charged zinc species from excess acid can result in acid-related pseudo-astringency, although not as much astringency as results from the presence of therapeutic Zn2+ ion dosages. Pseudo-astringency must not be confused with astringency from positively charged zinc, as acidified negatively charged zinc compositions appear to increase duration of common colds.

    ZIA values and mMolT concentration of Zn2+ ions increase at a faster rate than expected from increases of zinc acetate in lozenges (see Figure 23). Non-linearity suggests factors other than lozenge zinc content play a larger role in efficacyIf completely eliminating astringency from zinc lozenges is more important than curing the common cold, then zinc lozenges will not become a useful treatment for common colds. Astringency is not viewed as a legitimate reason to reject zinc acetate lozenges as a cure for the common cold. Rather, future clinical studies should focus on finding the minimum effective ZIA and mMolT Zn2+ ion concentration to produce a 7-day average reduction in the duration of colds without objectionable astringency.

    ZIA values and mMolT concentration of Zn2+ ions increase at a faster rate than expected from increases of zinc acetate in lozenges (see Figure 23). Non-linearity suggests factors other than lozenge zinc content play a larger role in efficacy. Because of the linearity in the relation between ZIA and efficacy demonstrated in Chapter 5, the present author suggests 23-mg zinc (77.2 mg zinc acetate dihydrate USP) lozenges with a 185 ZIA and 9.9 mMolT Zn2+ ion concentration will shorten common colds by an average of seven days or more. This dosage seems too astringent and too strong in well people doing flavor tests, but is not perceived as too astringent or too strong in people suffering from common colds.

    Alternatively, ZIA 100 zinc acetate lozenges containing 16 mg zinc are essentially always perceived as having a pleasant taste, and may also be expected to shorten colds by 7 days, although initial response may not be quite as strong.


    Chapter 7 References

    1. Cannan RK, Kibrick A. Complex formation between carboxylic acids and divalent metal cations. Journal of the American Chemical Society. 1938; 60:2314-2320.

    2. Hacht B and Berthon G. Metal ion-FTS nonapeptide interactions. A quantitative study of zinc(II)-nonapeptide complexes (thymulin) under physiological conditions and assessment of their biological significance. Inorganica Chimica Acta. 1987;136:165-171.

    3. Korant BD, Kaurer JC, Butterworth BE. Zinc ions inhibit replication of rhinoviruses. Nature. 1974; 248:588- 590.

    4. Berg LR and Martinson RD. Effect of diet composition on the toxicity of zinc for the chick. Poultry Science. 1972; 51:1690-1695.

    5. Eds: Lieberman HA, Lachman L, Schwartz JB. Pharmaceutical Dosage Forms: Tablets. New York:Marcel Deckker, Inc; 1989:1-3.

    6. Peck GE, Baley GJ, McCurdy VE, et al. Tablet formulation and design. In: Eds: Lieberman HA, Lachman L, Schwartz JB. Pharmaceutical Dosage Forms: Tablets. New York:Marcel Deckker, Inc; 1989:1.

    7. Mendes, RW, Anaebonam AO, Daruwala JB. Chewable tablets. In: Eds: Lieberman HA, Lachman L, Schwartz JB. Pharmaceutical Dosage Forms: Tablets. New York: Marcel Deckker, Inc; 1989:1.

    8. Shangraw RF. Compressed tablets by direct compression. In: Eds: Lieberman HA, Lachman L, Schwartz JB. Pharmaceutical Dosage Forms: Tablets. New York:Marcel Deckker, Inc; 1989:1.

    9. Mendell Catalog. Carmel, NY:Edward Mendell Co; 1991.

    10. Bolton TA and Reineccius GA. The oxidative stability and retention of a limonene-based model flavor plated on amorphous silica and other selected carriers. Perfumer & Flavorist. 1992;17:1-12.

    11. Paragraph 172.230. Microcapsules for flavoring substances. Code of Federal Regulations Title 21: Food and Drug Administration, Department of Health and Human Services, Parts 170-199, revised April 1, 1990, Office of the Federal Register National Archives and Records Administration: Washington, DC.

    12. Zinc acetate. Eds: Windholz M, Budavari S, Blumetti RF, et al. The Merck Index. Rahway NJ: Merck & Co; 1983: 1455.

    13. Briggs J, Finch P, MC Matulewicz, et al. Complexes of copper(II), calcium, and other metal ions with carbohydrates: Thin-layer ligand-exchange chromatography and determination of relative stabilities of complexes. Carbohydrate Research. 1981;97:181-188.






    Chapter 8. - Zinc Biochemistry

    Executive Summary Chapter 8 discusses fundamentals of the biochemistry of zinc. Zinc is an essential element in all cells of every species. Zinc deficiency impairs growth, and proper function of the immune system. Zinc is required in DNA and in its synthesis, and is vital to the function of zinc fingers in transcription factors, or gene-regulating proteins. Life could not have started billions of years ago without the unique ability of zinc to function as a nonenzymatic polymerase, suggesting a riddle with a Zn2+ twist -- which came first, the chicken or the egg? A role for zinc in the management of HIV and AIDS is discussed. Zinc, zinc gluconate, and zinc acetate are Generally Recognized as Safe (GRAS) substances. No evidence of toxicity of short term administration of therapeutic dosages of zinc has been found.

    The complete biochemistry of zinc is far outside the scope of this handbook. This survey is generally restricted to items of major interest, and items of importance in common cold research, such as toxicology. Many implications and effects of zinc nutrition and deficiency in human medicine are of significant clinical interest but are omitted or only briefly mentioned. The reader should consider a review of the many discussions by other sources regarding zinc in human nutrition, biochemistry and medicine.

    Zinc in Genetics

    Zinc is an essential element in the nutrition of human beings, animals, and plants. Zinc is required in the genetic make-up of every cell and is an absolute requirement for all biologic reproduction. Zinc is needed in all DNA and RNA syntheses and is required at every step of the cell cycle. DNA is about 5000 times less susceptible to damage by Zn2+ ion than is RNA, suggesting its role in the predominant evolutionary selection of DNA, rather than RNA, as the bearer of the primary genetic information.(1)

    In prebiotic chemistry on Earth billions of years ago, zinc most likely was the first effective nonenzymatic polymerase. Zinc remains an essential component of all DNA and RNA polymerases examined today.(2) With a poly C template, Zn2+ alone can catalyze the assembly of an activated GMP derivative (guanosine 5'-phosphoimidazolide) into poly G chains 30 to 40 residues in the natural 3'-5' linkage.(2) Although other metals are catalytic, Zn2+ ion produces greater fidelity.

    Zinc's function as a nonenzymatic polymerase suggests an inorganic answer to the age-old question, "Which came first the chicken or the egg?"

    "Zinc fingers" are finger-like protrusions extending from transcription factors or gene-regulating proteins and fastening to the wide, major groove of a DNA molecule.(3) Since the discovery of zinc fingers in 1985, over 200 proteins, many of which are transcription factors, have been found to incorporate zinc fingers. Zinc fingers rely totally upon Zn2+ ions for their form and function. Zinc fingers have been identified in species as diverse as yeast to human beings. About 1 percent of the DNA in human cells specify zinc fingers. As few as 2 and as many as 37 zinc fingers occur on gene-regulating proteins. Zinc fingers are believed to enable enzymes to transcribe a second genetic segment from DNA into RNA serving as a template for synthesis of a specific protein such as a string of amino acids or RNA itself. The finger-like projections are perfectly suited for DNA recognition by means of their three-dimensional shape. From an evolutionary standpoint, ancestral genes specifying a small protein of 30 or so amino acids would easily pick up zinc from the environment and would fold without assistance into a stable conformation where they would have the ability to bind to DNA and RNA.

    General Zinc Biochemistry

    About 2 grams of zinc is distributed throughout the body (average 10 to 200 mmg/gram) of an adult human being.(4) Absorption of dietary zinc occurs over the duodenal and jejunal regions of the gastrointestinal tract. Active transport of zinc into portal blood is mediated by metallothionein. Zinc competes with other metals for absorption, and absorption is believed greatly retarded by ingestion of fiber and phytates.(4,5)

    Plasma zinc is complexed to organic ligands. Zinc-albumin complexes account for about 50 percent of the zinc, and the metal is readily exchangeable throughout the peripheral circulation. About 7 to 8 percent is loosely bound to amino acid constituents in plasma. The remaining 40+ percentage of plasma zinc is largely bound to macroglobulins and unavailable for nutritional purposes. Serum and plasma zinc concentrations in adults range from 80 to 150 mmg/dL, although circadian diurnal fluctuations occur in concentration.(4) Circadian diurnal variation peaks at 9:30 AM and reaches a low at 8 PM with differences of 19 mmg/dL.(6) Rather than an enterohepatic circulation, zinc experiences a similar enteropancreatic recycling.(4)

    Zinc is an integral component of about 200 metalloenzymes, including carbonic anhydrase, alcohol dehydrogenase, carboxypeptidase, glutamic dehydrogenase, lactic dehydrogenase, and alkaline phosphatase as well as hormones, such as thymulin, testosterone, prolactin, and somatomedin.(4)

    Zinc deficiency symptoms are nonspecific, perhaps in part because of their need in so many enzymes and their critical roles in both protein synthesis and molecular genetics. Many enzymes may become nonfunctional in the absence of zinc, even though the presence of the enzyme remains undisturbed. The integrity of cell membranes, including the integrity of red and white blood cells, depends upon loosely bound ionic zinc. Moreover, zinc deficiency is a cause of 33 percent of all olfactory disorders. In many respects, the total picture of zinc deficiency is reminiscent of essential amino acid deficits.(4)

    Zinc deficiency stunts growth and causes serious metabolic disturbances. Inadequate intake in people and animals results in serious immunodeficiency, increased numbers of infections, increased severity of infections, stunted growth, and delayed sexual maturation. As deficits become worsened, skin and orificial lesions develop only to be subjected to an unchallenged bacterial invasion, yet lesions do not mount a significant inflammatory response.(4) Therefore, severe zinc deficiency produces a patently obvious immunodeficiency in the cell-mediated (T-cell) immune system. Advanced deficiency culminates in diarrhea, severe wasting, and ultimately death. This scenario is typical of at least 12 animal species including man.(4)

    Zinc, HIV and AIDS

    Zinc deficiency symptoms are similar to those of patients suffering from AIDS. Siegal and co-workers first described AIDS patients with concurrent herpes simplex infection in 1981. One impression of the disease to Siegal and co-workers was immunosuppression induced by zinc deficiency.(7) Zinc serum levels were normal. Normalcy could have been brought about by the patients' advanced state of catabolism as patients were all anorectic and cachectic. Additional zinc was administered to these first four AIDs patients of record with no effect. The amount of zinc given was not stated but was probably about 15 mg/day, the recommended daily allowance (RDA).

    Unless zinc was given at very high doses for 10 days or longer to restart the thymus in the manner of Golden and colleagues (about 150 mg/day, or about 1 mg per pound of body weight),(8) little could be expected. This amount of zinc is ten times the RDA and is essentially identical to the dosages used to treat colds. Libanore and co-workers found significantly lower (P < 0.001) zinc in serum in AIDS patients. Zinc decreased with the worsening of the clinical and immunological picture (CD4 helper inducer cells), suggesting administration of zinc to the authors.(9)

    Weiner suggested administration of zinc to homosexual AIDS patients.(10) Low serum zinc, frequently found in male homosexuals,(10) IV drug abusers, and other malnourished persons will significantly impair T-cell function. Impairment would prevent complete elimination of virus after initial T-cell response or at any time during infection. Demise of T-cells and immunosufficiency, and increases in severity of HIV infection, and ultimately AIDS would result. Administration of 1 mg zinc per pound body weight per day used by Golden and colleagues,(8) or 100 mg zinc per day used by Duchateau and colleagues(11,12) given on a prophylactic basis or after the time of contracting HIV infection should restore or improve thymic function, double T-cell function, increase T-cell count, help stabilize plasma cell membranes, and have a chance of eliminating HIV infection or preventing HIV infection from progressing to AIDS. (See Chapter 2 for further information on the effects of zinc in stimulating T-cell lymphocyte function, including reduction of suppressor T-cells, and enhancement of interferon production.)

    J. M. Coffin reported that the long, clinically latent phase that characterizes human immunodeficiency virus (HIV) infection of humans is not a period of viral inactivity, but an active process in which cells are being infected and dying at a high rate and in large numbers (billions per day).(13) These results led him to a simple steady-state model in which infection, cell death, and cell replacement are in balance, and imply that the unique feature of HIV is the extraordinarily large number of replication cycles of both T-cell lymphocytes and viruses that occur during infection of a single individual. Considering the extrodinary dynamics of T-cell growth and replacement, administration of zinc in the dosages suggested seems mandatory to provide sufficient zinc to allow uninterupted T-cell growth, and more particularly transformation of T-cell lymphocytes to the activated state.

    Unless all HIV are successfully eliminated by activated T-cells, coincidental severe, untreated bacterial infections after HIV infection could result in a LEM reaction by the liver temporarily withdrawing zinc from the blood and T-cells,(13,14) perhaps resulting in temporary loss of T-cell control of HIV, resulting in HIV reinfection, as would be the case with any therapeutic agent used in the treatment of HIV.

    In HIV infection, zinc serum concentrations should be maintained near the upper limit of the normal range (150 mmg zinc/dL), but not above the normal range. Immunosuppression and other hemopoietic side effects from twice normal or greater zinc serum concentration may result (see below and specifically references 32, and 34), particularly if serum concentrations of copper, iron, and manganese fall below their normal ranges. Conversely, notice the familial hyperzincemia discussion below.

    Experimental zinc treatment was tested for immunostimulatory effects in an HIV-infected 180-pound man. T-cell function change [the resultant of T-cell count change (from 90 to 120) and the fraction of T-cells activated change (from 7 to 10 percent)], doubled within the first 30 days. As the patient left the study, follow-up was not possible. Dosage tested was 3 to 5 tablets daily with each tablet containing 30 mg zinc, 2 mg iron, 2 mg manganese, and 0.3 mg copper.(15)

    GRAS Status Assessment

    Certain zinc salts are food substances and are Generally Recognized As Safe (GRAS). In 1973, the Life Sciences Research Office re-evaluated health aspects of supplementing food with certain GRAS zinc salts that were commonly used as food ingredients.(16) Their assessment was based upon information summarizing worldwide scientific literature gathered by the Food and Drug Administration from 1920 to 1970, supplemented by literature searches of Toxline and Medline available as of November 1973, and summarized in the following paragraphs. The Select Committee on GRAS Substances concluded:

    "There is no evidence in the available information on zinc sulfate, zinc oxide, zinc acetate, zinc carbonate, and zinc chloride that demonstrates, or suggests reasonable ground to suspect, a hazard to the public when they are used at levels that are now current in the manner now practiced. However, without additional data, it is not possible to determine whether a significant increase in consumption would constitute a dietary hazard."(16)

    The Select Committee found daily intake of zinc in the total diet varied considerably with age. The observed daily intake of elemental zinc per kilogram of body weight is found in Table (16). After reviewing the available data, the Select Committee commented that because of the central role of zinc as either an activator of certain enzymes or as a coenzyme in many metabolic reactions, relatively large excesses of zinc salts in the diet can lead to metabolic dysfunction. In particular, interaction of zinc with several other mineral nutrients, notably iron, copper, manganese and calcium, suggests major modification of zinc nutritional balance might lead to significant metabolic disturbances. In consideration of the potential for metabolic disturbance by toxic doses of zinc, and currently wide nutritional use of zinc sulfate and zinc oxide in infant formulas, the committee suggested expanding knowledge of interactions of zinc salts in association with dietary levels of other essential mineral nutrients.

    The committee suggested establishing maximum limits for levels of zinc salts in foods, particularly in formulas for infants, since this segment of the population now consumes the highest level of zinc salts when calculated on a daily or body weight basis.

    Table 16. Possible daily intake of zinc in milligrams per kilogram of body weight

    ___________________________________________________________________________
    
    Age group   Possible daily intake in milligrams / kilogram body weight
    			Average intake		Maximum intake
    ___________________________________________________________________________
    
    0-5 montths		     5.59		     10.25
    6-11 months		     0.72		      3.41
    12-23 months		     0.17		      0.19
    2-65 years	           < 0.01		    < 0.01
    ___________________________________________________________________________
    

    The present author suggests lowering infant zinc intake may be erroneous. Lowering zinc content excessively in infant foods may contribute to infant immunosuppression, progression of HIV in infected infants to AIDS, and impaired growth. Human colostrum has been measured to contain 825 mmg/dL on the first day of lactation, falling to 507 mmg/dL on the fifth day of lactation, remaining at over 200 mmg/dL until about the third month of lactation, remaining at over 200 mmg/dL until about the third month of lactation, and at 70 mmg/dL for nearly the entire first year of life.(17) Zinc from colostrum activates infant cell-mediated immunity as well as stimulates cell growth. Cell mediated immunity must remain suppressed in the fetus and uterus to prevent host-graft disorders. Human amniotic fluid contains an antibacterial amount of zinc 4.4 times serum concentration.(18)

    The Select Committee found orally ingested zinc to be absorbed largely from the duodenum. The degree of absorption is substantially affected by nutritive status with respect to zinc, dietary phytate, calcium, and phosphorus. Usually about 8 to 10 percent of zinc ingested by rats, cats, and dogs is absorbed, and the rest is excreted in feces. Retention may be higher in bone and skin than in other tissues, but the element is present and needed in every cell. The average biologic half-life of zinc in the adult man is 154 days. As happens with other metals, zinc salt ingested in toxic amounts cause a variety of metabolic changes.

    Toxic doses of zinc inhibit intestinal alkaline phosphatase, xanthine oxidase, liver catalase, cytochrome oxidase, and succinic dehydrogenase; also, toxic doses modify excretion of nitrogen, phosphorus, and sulfur. For example, feeding zinc oxide as 1 percent of the diet of rats resulted in increased urinary excretion of nitrogen, while phosphorus and sulfur excretion was reduced. Fecal excretion was also increased, resulting in decreased net retention. Urinary excretion of both uric acid and creatine was increased.(16)

    The most important adverse effect of feeding toxic doses of zinc appears to be a specific microcytic hypochromic anemia, probably related to changes in iron and copper utilization. For example, decreases in iron storage proteins were observed when rats were fed a diet containing 0.4 percent zinc as zinc oxide. In other studies, diets containing 0.75 percent zinc resulted in decreased red cell life spans and increased iron excretion. Feeding an excess of zinc oxide (0.6 percent as zinc) to rats resulted in a decrease in both iron and copper levels of all tissues, explaining most of the enzyme changes. This effect of zinc excess on iron and copper metabolism appears to be the result of interference with iron and copper utilization at the cellular level and the increased excretion of copper. Evidence for this interaction is observed in studies of iron and copper supplementation. Supplementation of these metals can reverse anemia caused by excess zinc feeding. A similar interaction has been found with calcium and manganese. Increasing dietary calcium increased loss of zinc in rats and resulted in decreased absorption and decreasing turnover. In other studies, high calcium and phosphorus intakes appeared to increase zinc requirement in rats. By contrast, feeding an excess (0.75 percent zinc as zinc carbonate) in diets of young rats for one week resulted in a marked decrease in bone calcium and phosphorus.(16)

    In the rat, a lethal dose in 50 percent of cases (LD50) has been reported to be 1374 mg per kg for both zinc sulfate heptahydrate and for zinc acetate heptahydrate but 750 mg per kg for zinc chloride. Values of similar magnitude have been reported for mice and rabbits. One human fatality has been reported. A woman's death was attributed to zinc sulfate poisoning following accidental consumption of about 30 grams of the salt. This intake amounted to about 500 mg per kilogram of body weight, a dosage similar to dosages found to be often lethal in animal studies. Many short-term tests with high levels of zinc salts fed to different animal species have shown no adverse effects at levels below 100 mg of the salt per kilogram per day, but curiously, extensive studies indicate that feeding zinc oxide or zinc sulfate at levels greatly in excess of 500 mg of the salt per kilogram have no consistently adverse effects. The nature of the compound appears to play a significant role in toxicity. Limited studies of zinc sulfate intake have been conducted in human beings. There was no evidence of toxicity at levels of up to 660 mg per day of the heptahydrate (about 10 mg of the salt per kg per day) for up to 3 months.(16)

    Long-term dosages in rats have been carried out with zinc chloride, oxide, carbonate, and sulfate. These studies, extending for one year and over three generations, showed no effect at levels up to 0.25 percent of diet. In other investigations, zinc sulfate fed at dietary levels of about 100 ppm to rats and dogs was reported to cause hematologic changes including microcytosis, coupled with polychromasia in some animals and hyperchromomasis in others; in addition, more rapid turnover of red blood cells was observed.(16)

    No evidence of carcinogenicity of several zinc salts was noted in rat studies over three generations nor in feeding rats zinc oxide (equivalent to 34.4 mg of zinc daily for 29 weeks), or zinc carbonate (equivalent to 1 percent zinc in diet) for 39 weeks. No significant carcinogenic differences between zinc-treated mice (5,000 ppm zinc as zinc sulfate) and control groups were observed. These findings, the comprehensive critical analyses of the literature by experienced investigators, and recent reviews by two laboratories specializing in experimental carcinogenesis make it evident than zinc salts taken orally should not be considered a carcinogenic hazard.(16)

    Animal reproduction studies performed through several generations have disclosed no evidence of any adverse effect on fertility, gestation, and health of fetus from feeding diets of up to 0.25 percent zinc chloride, zinc oxide, zinc carbonate, or zinc sulfate to rats. In addition, specific studies of effects of excess dietary zinc fed as oxide, malate, acetate, citrate, or sulfate on chemical composition and enzymatic activities of maternal and fetal tissues have shown no adverse effects. Teratologic tests on three species of animals were negative: daily oral administration of up to 30 mg zinc sulfate per kg of body weight in mice (day 6 through day 15 of gestation), up to 42.5 mg per kg in rats (day 6 through day 15 of gestation), and up to 88 mg per kg in hamsters (day 6 through day 10 of gestation) had no clearly discernible effect on nidation or on maternal or fetal survival. The number of abnormalities observed either in soft or skeletal tissues of the test groups did not differ from the number occurring spontaneously in sham-treated controls.(16)

    Currently several zinc compounds are listed as GRAS by the Food and Drug Administration (FDA), but zinc acetate is not listed, although both zinc and acetic acid are listed.(19) Zinc acetate was a GRAS substance before re-evaluation by the Select Committee on GRAS substances in 1973, and was again found to be GRAS by the Select Committee in 1973.(16) Zinc acetate was not included in the GRAS list by the FDA in CFR 21 because no food use has been identified for it before development of zinc acetate lozenges, and it was not being used in foods. Zinc acetate may not be currently used in foods because (a) zinc acetate has an extremely sharp and offensive taste when not diluted with sugars, and (b) zinc acetate is extremely reactive with most food ingredients. An official USP XXI monograph for zinc acetate exists.(20)

    Heico Chemicals, Inc. of Delaware Gap, Pennsylvania, appears to be the only U.S. company offering large volume sales of zinc acetate dihydrate U.S.P. suitable for use in zinc acetate lozenges. Zinc acetate dihydrate U.S.P. currently is used (a) as a component in zinc-eugenol dental cement to accelerate setting, (b) as a component of an eye lotion and eye drops in the treatment of conjunctivitis, (c) occasionally as an astringent, (d) as a styptic, and (e) as an emetic for both human and animal usage. Heico has no drug master file on zinc acetate dihydrate U.S.P. Heico's zinc acetate dihydrate U.S.P. product is currently used by only one reseller in the amount of one ton per year.

    Recent Human Safety and Toxicologic Data

    In 1979, Prasad found zinc as being relatively nontoxic in comparison with other trace metals.(21) Many of the toxic effects attributed to zinc in the past are actually attributable to contaminants such as lead, cadmium, or arsenic. Zinc is noncumulative, and the proportion absorbed is thought to be inversely related to the amount ingested. Vomiting, a protective phenomenon, occurs after ingestion of large quantities of zinc. Two grams of zinc sulfate have been recommended as an emetic. Three types of acute toxic reactions to zinc have been reported in human beings. The first type is "zinc fume fever" characterized by pulmonary manifestations, fever, chills, and gastroenteritis observed in industrial workers who are chronically exposed to hot zinc oxide fumes. In the second type, toxicity was observed in a 16-year-old boy who slowly ingested 12 grams of metallic zinc dust over a period of 2 days. This condition was characterized by drowsiness, lethargy, and increased serum lipase and amylase levels without additional sequela. The third type of acute zinc toxicity was observed in patients with renal failure following hemodialysis using water stored in a zinc-galvanized tank. These patients suffered from nausea, vomiting, fever, and anemia.

    The symptoms of zinc toxicity in human beings include dehydration, electrolyte imbalance, abdominal pain, nausea, vomiting, lethargy, dizziness, and lack of muscular coordination. Acute renal failure will occur within hours of ingesting large amounts of zinc chloride. Death is reported to have occurred after ingestion of 45 grams of zinc sulfate. This dose is considered massive, considering the daily requirement of zinc for man is in the range of 15 to 30 mg/day. The competition between zinc and copper for intestinal absorption and protein-binding sites is well known, and there is a high probability that copper deficiency will be induced in patients receiving daily high amounts of zinc for at least a month.(21)

    In 1979 the National Research Council sub-committee on zinc found it not to be highly toxic. Zinc toxicosis occur only when high dose levels overwhelm the homeostatic mechanisms controlling zinc uptake and excretion. Reports of zinc tolerance as well as toxicosis in human beings are sparse, but existing evidence suggests that 500 to 1,000 milligrams or more of zinc may be ingested on a daily basis without outwardly observable adverse effects. Ten or more grams of the metal taken as a single oral dose may produce gastrointestinal distress, including nausea, vomiting, and diarrhea. The committee also found ingestion of large doses of zinc to reduce beneficially toxic stores of cadmium.(22)

    By 1988, Cunnane's review had little more to offer on the toxicity of zinc, although he was more restrained than the National Research Council. Cunnane suggested that zinc was not completely nontoxic, even in therapeutic dose range (50 to 300 mg/day) on a long-term basis. Frequently, doses of zinc in excess of 50 mg causes gastrointestinal side effects, including nausea. Zinc has biphasic and triphasic effects on many pathways and on the immune system, particularly T-cell lymphocyte function as will be discussed later in this section. Zinc's suppression of copper, iron and manganese utilization may also be an important detriment in the long run without their concurrent administration. Administration of zinc may beneficially deplete stores of iron resulting in a reduced incident of angina pectoris and ischemia. Zinc is well known to compete with these metals for gut absorption sites and blood transport proteins. Long-term doses of zinc required to deplete copper are reported to vary from 150 to 5,000 mg/day.(23)

    Pharmaceutical administration and uses, adverse effects, absorption, and the fate of zinc and zinc compounds including zinc acetate were reviewed in Martindale The Extra Pharmacopoeia in 1989.(24) No significant indications of toxicity or adverse effects were reported from therapeutic doses of zinc, although numerous pharmacologic uses of zinc, including zinc gluconate lozenge treatment for common colds, were reported. Probable lethal oral doses of soluble zinc salts including zinc acetate were reported between 50 mg per kg body weight (between one teaspoon and one ounce for an adult) and 5 grams per kg body weight (between 1 ounce and one pint for an adult).

    In Clinical Toxicity of Commercial Products, Gosselin reported the toxicity rating of soluble zinc salts was 3 to 4, or moderately toxic to very toxic.(25) Better estimates place probable lethal dose for a human being at 500 mg per kg, which is close to rat LD50 dose of 750 mg per kg for zinc acetate. For a 175 pound man, this would mean consuming between 40 and 60 grams of zinc acetate, which is about 3 to 5 heaping tablespoons.

    Numerous other original and review articles found no toxicity at levels used to treat common colds, particularly when used only for 7 days or less.(26-31)

    The finding of reversible, adverse immune system effects and decreased plasma high-density lipoprotein-cholesterol by Chandra when zinc serum levels were increased to double normal zinc serum levels(32) needs reconciliation with evidence showing some families have chronic zinc serum concentrations 3 to 5 times normal. Heritable hyperzincemia seemed to occur without obvious harm, and family members with high zinc serum content lived normal lives.(33)

    Even in a case of extreme abuse of zinc gluconate (10- to 20-fold the recommended 23-mg zinc dosage for common colds) taken every 2 hours for 4 months, the principal clinical findings consisted of anemia, neutropenia, very high alkaline phosphatase, a serum zinc concentration 10 times higher than normal (antiviral), and copper and manganese concentrations one-tenth normal. These findings were reversed with no apparent harm after withdrawal of zinc and administration of trace amounts of copper and manganese. Also, the patient was not ill during the time of apparent toxic overdose of zinc gluconate.(34) This observation is interesting as it documents an antiviral zinc serum level nearly 10 times normal, showing that relatively normal cell life and human life at antiviral serum zinc concentrations is possible.

    With lower amounts of oral zinc supplementation, (15, 50 and 100 mg zinc per day), Freeland-Graves observed no consistent changes in either plasma cholesterol or high-density lipoprotein-cholesterol but did observe a significant negative correlation between dietary copper and plasma cholesterol.(26)

    Consequently, effects of elevated zinc serum concentration on cholesterol observed by Chandra are actually caused by reductions in copper serum concentrations induced by elevated zinc, rather than being caused directly by elevated zinc.

    Lack of Toxicity in Common Cold Studies

    From the perspective of treatment of common colds with zinc lozenges for 7 days, significant benefits to T-cell immune system occurred in Chandra's patients during the first 2 weeks while zinc serum levels remained in the upper normal range.(32)

    As demonstrated by Farr and others, zinc serum level and other indicators did not leave normal ranges during administration of 23 mg zinc from zinc gluconate administered every 2 hours for 7 days.(35) No significant differences in vital signs between patients receiving zinc and patients receiving placebo occurred. Clinical laboratory tests, including complete blood count, differential leukocyte count, metabolic profile, urinalysis, and levels of copper and zinc in serum showed no significant differences between the two groups except for an increased mean level of zinc in serum of 105 versus 88 mmg zinc/dL (P < 0.001, t = 4.40). Normal levels of zinc in serum are 70 to 150 mmg/dL in the reference laboratory.(35)

    In the English study, Al-nakib and colleagues found a minor variation in concentration of zinc in plasma of volunteers, although no values were outside reference limits.(36) All volunteers receiving zinc showed a marked increase in urinary zinc excretion.(36)

    Zinc acetate (150 mg elemental zinc per day) has been sponsored as an orphan drug for long-term treatment of Wilson's disease.(37)

    Possible Adverse Effect in Pregnancy

    As none of the clinical trials of zinc lozenges for common colds included pregnant women, caution in pregnancy may be warranted as with any treatment during pregnancy.

    Kumar reported in an uncontrolled trial effects of supplementing 100 mg zinc sulfate daily during the third trimester of pregnancy to subjects on diets providing 6 mg zinc/day (total 31 mg zinc/day). Of the four subjects treated by Kumar, three premature births and one stillbirth occurred, compared to 20 to 30 percent considered normal for women in underdeveloped countries including India.(38) Undesirable changes in the fetus have been associated with intake of very low or excessive amounts of zinc, magnesium, and manganese.(39)

    Hambidge and associates reported no change in maternal serum status or other problems from supplemented diets providing 22 mg zinc per day in a study of 10 middle-income United States women.(40) Zinc in perinatal nutritional supplements is either absent or most often present in 25-mg dosages.(41)

    Industrial Safety and Material Safety Data Sheet for Zinc Acetate

    Large non-pharmaceutical acute and chronic dosages and concentrations of a number of zinc compound powders used in industry, including zinc chloride, zinc sulfate, zinc acetate, zinc oxide, and zinc gluconate, are considered toxic to extremely toxic and painful to tissues of the upper and lower respiratory system. In sufficient concentrations, the powders can increase histamine release from mast cells,(42) causing inflammation and edema. In the special case of zinc chloride, death can occur primarily from the extremely caustic effects of chloride on respiratory tissues. Zinc fume fever, an acute disability, can occur when zinc fumes are inhaled from metal heated to a temperature above its melting point. This disease is most commonly associated with inhalation of recently formed zinc oxide fumes. Moderate exposure to zinc oxide dust does not cause zinc fume fever to the extent found with freshly formed zinc fumes, apparently because of the aggregation of fume particles. Zinc oxide dust has been said to relieve asthma when briefly inhaled.

    OSHA requires Material Safety Data Sheets (MSDS)(43,44) for chemicals used in industry. MSDS summarize important material safety data for the manufacturer's product. MSDS reports by Heico Chemicals, Delaware Water Gap, Pennsylvania, a manufacturer of zinc acetate dihydrate USP, and by J. T. Baker, Phillipsburg, New Jersey, a manufacturer of reagent-grade zinc acetate dihydrate, show zinc acetate to be a slight health and flammability hazard and a moderate contact hazard. Zinc acetate's chemical formula is Zn.(CH3CO2)2.2H2O. Molecular weight of the dihydrate is 219.49, and 183.47 for anhydrous. CAS numbers are 5970-45-6 for dihydrate and 557-34-6 for anhydrous. The melting point is 237 C. Solubility is appreciable at 1 g/2.3 ml water, and 1.6 ml boiling water. One gram dissolves in 30 ml alcohol or about 1 ml of boiling alcohol. Specific gravity is 1.735. The pH of zinc acetate is 6.3. Zinc acetate's oil/water partition coefficient was not available, but is expected to be zero. Zinc acetate dihydrate is a white crystal, and the anhydrous form is amorphous. Both have a faint acetic acid odor. Vapor density is 6.3 (air = 1).

    Zinc acetate is not volatile and essentially does not evaporate. The dihydrate may be dehydrated at 105 C. Zinc acetate is not combustible and is not a fire hazard, although excessive heating may release acetic acid fumes. Zinc acetate is a stable chemical when unheated, and hazardous polymerization does not occur at any temperature. Zinc acetate is incompatible with alkalies and strong oxidizing agents and will chemically react with many organic and inorganic substances. Zinc acetate decomposes upon severe heating to zinc oxide, carbon monoxide, and carbon dioxide. In both acute and chronic industrial overexposures, zinc acetate is an eye irritant and respiratory hazard.

    Overexposure causes eye redness and irritation. Continuous inhalation of dust, concentrated mists, or aerosols may cause irritation of upper respiratory tract, tightness and pain in chest, and coughing. Ingestion causes nausea, vomiting, gastrointestinal irritation, and burns to the mouth and throat. Inhalation of concentrated mists aggravates respiratory disorders such as emphysema and asthma. Zinc acetate is not carcinogenic, and teratologic tests on three species of animals were negative. Oral rat LD50 is 2460 mg/kg. Dry zinc acetate is not absorbed through the skin, but hot, concentrated solutions can cause severe skin irritation or burns. No chronic effects of overexposure have been identified.

    Bulk zinc acetate is considered a hazardous, but not extremely hazardous industrial chemical and is regulated by several governmental agencies. No special industrial protective equipment is needed other than good ventilation, safety goggles, clothing, and gloves. First aid for oral ingestion, if the person is conscious, is to give large amounts of water and induce vomiting. If inhaled, the person is to move to fresh air. If the victim is not breathing, artificial respiration is indicated. In case of eye or skin irritation, the area should be washed with water.

    Concluding Comments on Toxicity

    Lipophilic zinc complexes easily penetrate the cell plasma membrane and were found to be cytotoxic in direct relationship to their lipophilicity by Merluzzi and colleagues,(45) and one might wonder if interference with zinc fingers is one cause of such toxicity. Conversely, some symptoms of disease, such as delayed sexual maturity, rising from insufficient dietary zinc can now be attributed to the inability of estrogen and androgen receptors to fold properly in the absence of zinc.(3)

    Although the use of Zn2+-ion releasing zinc lozenges causes a localized extracellular rise in Zn2+ ions at the concentrations used, they decrease the permeability of the cell plasma membrane to exclude additional Zn2+ ion absorption into the interior of cells. If zinc accumulated in cells from zinc lozenge treatment, zinc would be cytotoxic. Consequently, only zinc compounds releasing 100 percent of their zinc at pH 7.4 as Zn2+ ions, such as zinc acetate, are believed completely free of zinc cytotoxicity. Other zinc compounds releasing neutral cell membrane-penetrating zinc complexes may result in some degree of cytotoxicity, manifested in a variety of ways from oral irritation to outright toxicity.

    Zinc, in the form of zinc gluconate or zinc acetate lozenges, used at doses of 23 mg zinc or less, 9 times per day for 1 week, does not raise zinc serum levels and has a record of safety with no unreported side effects known to exist since their use began in 1979.

    Chapter 8. References

    1. Butzow JL, Eichhorn GL. Different susceptibility of DNA and RNA to cleavage by metal ions. Nature (London). 1975;254:358-359.

    2. Kornberg A. Origin of DNA on Earth. In: 1982 Supplement to DNA Replication. San Francisco: W. H. Freeman Co.; 1982:S224.

    3. Rhodes D, Klug A. Zinc Fingers. Scientific American. 993;268: 56-65.

    4. Zapsalis C and Beck RA. Food Chemistry and Nutritional Biochemistry. New York:John Wiley & Sons; 1985:1006-1009.

    5. Oberleas D, Harland BF. Nutritional agents which affect metabolic zinc status. In: Zinc Metabolism: Current Aspects in Health and Disease. New York:Alan R. Liss, Inc.; 1977:11-24.

    6. Markowitz ME, Rosen JF, Mizruchi M. Circadian variations in serum zinc (Zn) concentrations: correlation with blood ionized calcium, serum total calcium and phosphate in humans. American Journal of Clinical Nutrition. 1985; 41:689-696.

    7. Siegal FP, Lopez C, Hammer GS, et al. Severe acquired immunodeficiency in male homosexuals, manifested by chronic perianal ulcerative herpes simplex lesions. The New England Journal of Medicine. 1981;305:1439-1444.

    8. Golden MHN, Jackson AA, Golden BE. Effect of zinc on thymus of recently malnourished children. The Lancet. Nov. 19, 1977:1057-1059.

    9. Libanore M, Bicocchi R, Raise E, et al. Zinc and lymphocyte subsets in patients with HIV infection. Minerva Medica (Italy). 1987;78:1805-1812.

    10. Weiner RG. AIDS and Zinc Deficiency. Journal of the American Medical Association. 1984;252:1409-1410.

    11. Duchateau J, Delepesse G, Vrijens R, et al. Beneficial effects of oral zinc supplementation on the immune response of old people. The American Journal of Medicine. 1981;70:1001-1004.

    12. Duchateau J, Delespesse G, Vereecke P. Influence of oral zinc supplementation on the lymphocyte response to mitogens of normal subjects. The American Journal of Clinical Nutrition. 1981;34:88-93.

    13. Subcommittee on Zinc, Committee on Medical and Biological Effects of Environmental Pollutants, Division of Medical Sciences, Assembly of Life Sciences National Research Council. Zinc. Baltimore:University Park Press; 1979;235.

    14. Beisel WR, Pekarek RS, Wannemaker RW Jr. Homeostatic mechanisms affecting plasma zinc levels in acute stress. In: Prasad AS, Oberleas D eds. Trace Elements in Human Health and Disease. New York:Academic Press; 1976;97.

    15. Weaver CA, Austin, Texas. Manuscript in progress.

    16. Select Committee on GRAS Substances. Evaluation of the Health Aspects of Certain Zinc Salts as Food Ingredients, (SCOGS-21). Bethesda, MD: Life Sciences Research Office, Federation of American Societies for Experimental Biology. 1973.

    17. Shaw JCL. Trace elements in the fetus and young infant. American Journal of Diseases of Children. 1979;133:1260-1268.

    18. Prasad AS. Zinc in Human Nutrition. Boca Raton, FL:CRC Press. 1979:24.

    19. Part 182-Substances Generally Recognized as Safe, and Part 184-Direct Food Substances Affirmed as Generally Regarded as Safe. Code of Federal Regulations Title 21:Food and Drug Administration, Department of Health and Human Services, Parts 170-199, revised April 1, 1990, Washington DC:Office of the Federal Register National Archives and Records Administration; 1990.

    20. Zinc Acetate. The United States Pharmacopoeia, Twenty-Second Revision and National Formulary XVII, Rockville, MD:United States Pharmacopoeia Convention. 1990:1462.

    21. Prasad AS. Zinc in Human Nutrition. Boca Raton, FL: CRC Press; 1979:66-68.

    22. Subcommittee on Zinc, Committee on Medical and Biological Effects of Environmental Pollutants, Division of Medical Sciences, Assembly of Life Sciences National Research Council. Zinc. Baltimore, MD:University Park Press; 1979:305.

    23. Cunnane SC. Zinc: Clinical and Biochemical Significance. Boca Raton, FL: CRC Press;1988:65-66.

    24. Zinc. In Reynolds JEF, Parfitt K, Parsons AV, et al. eds. Martindale, The Extra Pharmacopoeia, Twenty-Ninth Edition. London:The Pharmaceutical Press; 1989.

    25. Gosselin RE, Smith RP, Hodge HC, et al. Clinical Toxicology of Commercial Products. Fifth ed. Baltimore:Williams & Wilkins; 1984:II-143.

    26. Fox MRS. Zinc excess. In Miles CF. Zinc in Human Biology. New York:Springer-Verlag; 1989.

    27. Prasad AS. Trace Elements and Iron in Human Metabolism. New York:Plenum Medical Book Company; 1978:328-329.

    28. Underwood EJ. Trace Elements in Human and Animal Nutrition. 4th ed. New York:Academic Press; 1977:230-232.

    29. Lantzsch HJ, Schenkel H. Effect of specific nutrient toxicities in animals and man: Zinc. In Rechcigl, Jr. Ed. CRC Handbook Series in Nutrition and Food. West Palm Beach, FL:CRC Press, Inc., 1978.

    30. Abdel-Mageed AB, Oehme FW. A review of the biochemical roles, toxicity and interactions of zinc, copper and Iron: I. Zinc. Veterinary and Human Toxicology. 1990; 32:34-39.

    31. Fosmire GJ. Zinc Toxicity. American Journal of Clinical Nutrition. 1990;51:225-227.

    32. Chandra RK. Excessive intake of zinc impairs immune responses. Journal of the American medical Association. 1984;252:1443-1446.

    33. Smith JC Jr. Heritable hyperzincemia in humans. In Brewer GJ, Prasad AS, eds. Zinc Metabolism: Current Aspects in Health and Disease. New York: Alan R. Liss, 1977.

    34. Pfeiffer CC, Papaioannou R, Sohler A. Effect of chronic zinc intoxication on copper levels, blood formation and polyamines. Orthomolecular Psychiatry. 1980;9:79-89.

    35. Farr BM, Conner EM, Betts RF, et al. Two randomized controlled trials of zinc gluconate lozenge therapy of experimentally induced rhinovirus colds. Antimicrobial Agents and Chemotherapy. 987;31: 1183-1187.

    36. Al-Nakib W, Higgins PG, Barrow I, et al. Prophylaxis and treatment of rhinovirus colds with zinc gluconate lozenges. Journal of Antimicrobial Chemotherapy. 1987;20: 893-901.

    37. Zinc Acetate. In: USP Drug Information for the Health Professional, V. Orphan Drugs and Biological Listing. Rockville, MD:The United States Pharmacopoeial Convention, Inc; 1992;2:58-59.

    38. Kumar S. Effect of zinc supplementation on rats during pregnancy. Nutrition Reports International. 1976;13:33-36.

    39. Krause MV, Mahan LK. Food, Nutrition and Diet Therapy. Philadelphia:W. B. Saunders Co.; 1979: 283.

    40. Hambidge KM, Krebs NF, Jacobs MA et al. Zinc nutritional status during pregnancy: a longitudinal study. American Journal of Clinical Nutrition. 1983;37:429-442.

    41. Physicians' Desk Reference. 47th ed. Montvale, NJ: Medical Economics Data; 1993.

    42. Harisch G, Kretschmer M. Some aspects of a non-linear effect of zinc ions on the histamine release from rat peritoneal mast cells. Research Communications in Chemical and Pathological Pharmacology. 1987;55:39-48.

    43. Material Safety Data Sheet for Zinc Acetate Dihydrate. Heico Chemical, Delaware Water Gap, NJ. 1993.

    44. Zinc Acetate Dihydrate. J.T. Baker, Phillipsburg, NJ. 1990.

    45. Merluzzi VJ, Cipriano D, McNeil D, et al. Evaluation of zinc complexes on the replication of rhinovirus 2 in vitro. Research Communications in Chemical Pathology and Pharmacology. 1989;66: 425-440.






    Chapter 9. Conclusions and Recommendations

    Executive Summary Chapter 9 draws conclusions and makes recommendations. Hydrated Zn2+ ions have potent antirhinoviral effects, powerful cell membrane protective actions, instantaneous cell pore-closing abilities, strong interferon-inducing properties, outstanding drying effects on secretory cells in nasal tissues, and effective anti-inflammatory action. Zn2+ ions have been shown highly useful in shortening the duration of common colds when used in specific lozenge treatment protocols. A serious difference of opinion concerning efficacy of zinc lozenges tested from 1984 through 1992 existed.

    The unifying ZIA method of analysis presented in this handbook provides complete reconciliation. All eight clinical zinc lozenge for common cold studies reviewed are equally valid, but each study portrays only a small facet of the over-all picture. Each of the studies represented responses from lozenges having greatly different ZIA values, as a result of greatly differing chemical compositions. Seven day reductions in average duration of common colds is possible and highly likely using lozenges with a ZIA 100 value.

    Recommendations for research on zinc acetate lozenge formulations, placebo matching, and common cold treatment protocols are also given. Methods found helpful to improve clinical results are given.

    Related uses for zinc acetate lozenges in allergy and mononucleosis, possible side effects, and contraindications are discussed.

    Evidence exists that clearly shows zinc gluconate lozenges to be effective in reducing duration of common colds; the only question is by how much, which depends upon ZIA values. Zinc gluconate mixed with all known sweeteners, except fructose, is not flavor-stable and always becomes very bitter within a few days to a few months without strong chelating additives. Low ZIA values from fully flavor-masked zinc gluconate lozenges preclude its use in commercial products. If zinc lozenges are to become successful in reducing duration of common colds, pleasant-tasting lozenges having a high ZIA value must be developed.

    Zinc acetate is extremely soluble and is 3.33 times as ionizable as zinc gluconate. Equivalent amounts of zinc from zinc acetate produce higher ZIA values and better results against common colds than zinc gluconate. Zinc acetate does not need flavor-masking when it is mixed with sucrose, dextrose, or fructose. Combinations are flavor-stable and have a pleasant taste and aftertaste. Because production of fully flavor-masked zinc gluconate lozenges having a ZIA value over 50 is practically impossible without increasing zinc content of lozenges, zinc gluconate is no longer considered viable for use in zinc lozenges as treatment for common colds. Because of superior properties, zinc acetate is the successor to zinc gluconate in lozenges to be used for treating or curing the common cold.

    Two basic zinc acetate lozenge formulations are recommended for use in treating or curing common colds: the standard design and the advanced design. The standard design relies upon saccharin to provide added sweetness to dextrose tablet base. The advanced design relies upon fructose to provide the necessary added sweetness. Both of these designs are fully developed in Chapter 7.

    Recommended Standard Zinc Acetate Lozenge Formulation

    Standard zinc acetate lozenges for treatment of the common cold are 7/8 inch in diameter, have standard convex faces, weigh 5 grams and are compressed to the point (about 6 to 10 tons) where further compression does not result in increases in average oral dissolution time.

    Standard design lozenges should contain as the active ingredient 10 to 20 mg of zinc from zinc acetate dihydrate USP within a tablet base comprised of Mendell's Emdex(r) agglomerated dextrose. The lubricant should be 125 mg glyceryl monostearate. Lozenges are pleasant tasting and flavor-stable, although insufficiently sweet to most palates. When necessary, saccharin (1 to 10 mg), and peppermint oil (0.5 to 5 mg) may be added, although such additives chemically and physically affect ZIA values. The zinc lozenges should have a ZIA value of about 150, dependent on other variables, primarily useage and dissolution rates. Such lozenges theoretically will shorten common colds by more than 7 days on average. However, the addition of saccharin may be undesirable by many.

    Recommended Advanced Design Zinc Acetate Lozenge Formulation

    The advanced design lozenges should have a ZIA value from 75 to 185. Advanced design lozenges are 5.0-gram lozenge having a diameter of 7/8 inch and standard convex faces. Lozenges release 15 to 23 mg Zn ion from zinc acetate and provide 5.4 to 10 mMolT Zn2+ ion concentration.

    Smaller 3/4 inch lozenges may be developed to overcome the objection by some users concerning the large size of the 7/8 inch diameter, 5-gram standard lozenge. Present experience indicates the possibility of a 4-gram lozenge, but lozenges lack sufficient sweetness without addition of saccharin or peppermint unless zinc dosages are similarly reduced. Present experience shows most people prefer the 5-gram lozenges without added sweeteners or added flavors.

    Advanced design lozenges are made with zinc acetate dihydrate USP, Mendell's Sweetrex(r) (70 percent Emdex(r) agglomerated dextrose and 30 percent crystalline fructose), and glyceryl monostearate lubricant without any other additives such as saccharin or flavors. They are more pleasant tasting and more flavor-stable without extra sweeteners or flavors.

    Changes in Formulations Allowable

    To establish accurate performance baselines, no changes or additions of other substances should be allowed until there are sufficient experimental lozenge studies to cause general acceptance of the findings.

    Although 3/4-inch advanced design lozenges are considered reasonably small, even smaller lozenges might be possible using non-palpable, direct compression dextrose or lactose, sweetened with sodium saccharin. The first stability constant of zinc and lactose is log K1 = 0.(1) Consequently, no reasonable complexation between zinc and lactose is possible. Saccharin will complex with zinc. Although complexation is believed to be slight, stability studies must be conducted before any use of chemically significant saccharin.

    Minimum Effective Dose

    The concept of minimum effective dose does not apply at dosage strengths below ZIA 100, as efficacy falls linearly with declining ZIA values. At some value substantially over ZIA 100, a minimum effective dose may be found. Exceeding the minimum effective dose would cause no further clinical improvement and would be accompanied by increased and unnecessary oral side effects.

    Manufacturing Variables Affecting ZIA

    As shown in Chapter 7, many variables can affect ZIA values of zinc lozenges. Lozenges require good quality control procedures during the manufacturing process. Average ZIA values vary between batches of lozenges when certain variables are altered. Average ZIA values must be established for each lozenge batch varying in terms of (a) zinc compound used, resulting in a different amount of Zn2+ ion present at pH 7.4; (b) compressive forces used in manufacture (may result in different average oral dissolution times); (c) inconsistent hopper filling (always results in different lozenge weights and compressive forces applied); (d) changes in tablet presses (may result in different average oral dissolution times); (e) variations in amount, type, or brand of lozenge ingredients used, including tablet base, lubricant, drying agent for flavor oils, flavor oils, and moisture; (f) changes in tablet punches and dies (resulting tablet shape changes); and (g) changes in lozenge sweetness or flavoring (might increase or decrease saliva production or lozenge dissolution rates).

    Importance of Placebo Matching

    The subject of placebo-blinding has received much attention in common cold research as researchers rely upon the statements of patients concerning well-being in the evaluation of several clinical results.

    Rejection of Vitamin C claims for shortened colds resulted from the ease by which patients were able to distinguish the difference between Vitamin C and placebo because of the well known taste of Vitamin C.(2) Authors including Linus Pauling,(3) Shult and co-workers,(4) and Eby and co-workers (see Chapter 4.A.1) found patients taking Vitamin C had milder or shorter colds. Because of the familiarity of its taste, the problem of placebo-blinding is considered to be serious in Vitamin C for common cold research.

    Farr and Gwaltney(5) hypothesized the results of Eby and co-workers,(6) and by association the results of the Al-Nakib and co-workers,(7) to have been faulty because of placebo unblinding. Their hypothesis was based upon tasting a single marked tablet of zinc gluconate and a single marked tablet of placebo by the same researchers.(5) There were some differences in taste.(5)

    The contention by Farr and Gwaltney of placebo-unblinding in the study by Eby and co-workers was not supported by evidence, either internal or external to the original trials because (a) no patient in the original study by Eby and co-worker knew the taste of zinc gluconate (or placebo); (b) there was no statistically significant difference in response between patients commenting on taste and patients not commenting in this study; (c) zinc and placebo lozenges were indistinguishable in taste and appearance in the study by Al-Nakib and co-workers; and (d) differences in results of all studies of zinc lozenge for common colds are entirely accounted for by differences in ZIA values.

    Even though the patients in the Al-Nakib study were in quarantine and were constantly observed and even though the authors noted that the taste and appearance of the zinc gluconate and placebo lozenges used were indistinguishable, some United States common cold researchers did not accept the English results because clear, unambiguous, thorough, statistical evidence was not published by Al-Nakib and co-workers proving unequivocally the absence of taste bias. The rationale, though unsubstantiated for zinc lozenges, is that even if patients are observed continuously by nurses and/or physicians each day of the study, patients receiving a more disagreeable dosage may not notice their colds as much as those on less agreeable medication, thus they might bias study results.

    Whether this contention of taste-bias is realistic or not is irrelevant in the United States. If no statistical evidence exists showing the zinc- and placebo-treated patients are equally likely to believe they are receiving an active or placebo, then results of the study will not be accepted.

    An independent clinical trial to determine if patients falsely report evidence of clinical well-being because of zinc and placebo lozenge taste differences has not been performed. These serious and unfounded allegations of errors in placebo-blinding for zinc lozenges remain unproved and in need of reconsideration.

    In view of the rigid, and perhaps un-realistic, expectations of perfect placebo blinding, all future zinc lozenges for common cold studies must adhere to the high standards established by Farr and Gwaltney in their article entitled "Zinc Gluconate: An Evaluation of Placebo Matching".(5) In their study Farr and Gwaltney conducted taste tests with several pilot studies using 20 patients, followed by two full trials with several hundred patients each. False results were reported to have first occurred with small groups of people using lesser amount of the bitter placebo, denatonium benzoate. By using larger amounts of denatonium benzoate, both zinc gluconate-citrate-treated and placebo-treated groups were equally convinced they were either receiving zinc, receiving placebo, or were uncertain.

    In the second and more accurate test, the option "don't know" was removed, and patients were required to decide between either "active" or "placebo" resulting in a random distribution of responses. Taste bias was not a consideration using the more bitter placebo in the zinc gluconate-citrate lozenge trial. A frequency distribution of side effects from the lozenges showed the higher doses of denatonium benzoate produced oral and systemic side effects essentially identical to side effects from zinc gluconate-citrate lozenges.

    This is not to say zinc acetate and placebo lozenges must have identical tastes. The zinc and placebo lozenges tested by Farr and Gwaltney had clearly distinguishable differences in flavor, but patients had no way of determining which treatment they were receiving.

    Differences in Taste Perception in Well and Ill Volunteers

    Placebo matching errors can result when flavor panel members who are well and uninfected with rhinovirus formally taste test zinc acetate and placebo lozenges. The taste perception of zinc acetate lozenges during colds is significantly different than while well. The perception of astringency and "strength" of the lozenges is much lower during colds, allowing larger dosages to be tolerated when ill than when well. Consequently, matched placebos during well-volunteer conditions may be unmatched during rhinoviral infection of volunteers. The directional tendency toward error cannot be known before testing the effect of rhinoviral illness upon the taste perception of the placebo. However, taste perception trend is towards improvement in perception of sweetness during treatment of colds with zinc acetate and gluconate lozenges, and perhaps with placebos. Whether this suggests placebos should be more or less bitter to well volunteers is unknown.

    Another source of placebo matching error would occur when ill patients are asked about their treatment on days after the start of treatment for their rhinovirus infection. As differences in response to treatment between zinc acetate and placebo treatment are great, asking if volunteers received active or placebo on the last day of the trial, for example, would produce obviously different results between the active and placebo groups.

    Placebo Lozenge Formula Considerations

    If researchers carefully evaluate their volunteers with quantifiable, objective, daily clinical data (viral titer, nasal mucous weights, nasal air flow rates, temperature, nasal and throat inflammation, coughing rate, lethargy, sleep requirement, number of pain relief tablets taken, and other physician-observed signs and symptoms of common colds), one would obtain the most accurate results with placebo lozenges having exactly the same ingredients as the active lozenges -- without zinc acetate, of course. The observation of such quantifiable data would seem to override the necessity for a perfectly matched placebo, but such is not true under United States assumptions.

    Addition of 0.25 to 1.00 mg of sucrose octaacetate or 0.00125 to 0.005 mg denatonium benzoate to provide a medicinal bitterness will help convince patients they have an active lozenge to produce the equivalent assessment of active- and placebo-treatment required by Gwaltney without harm to the placebo results. However, zinc acetate lozenges are not bitter, and such addition is unwarranted unless the bitter substance is also added to the active zinc acetate lozenges.

    Some volunteers, such as medical, biology and chemistry students, would know "acetate" in zinc acetate is related to acetic acid. They might expect the taste of vinegar; however, there is no vinegar taste or odor associated with oral use of zinc acetate lozenges. Only by rubbing wet lozenges between the fingers does a faint odor of vinegar on the fingertips occur. If acetic acid is added to the placebo, the addition should not exceed 0.5 mg acetic acid per 5-gram lozenge.

    To give identical blood pictures between active and placebo groups, the placebo may contain a highly chelated zinc compound such as zinc citrate. Zinc citrate is known to be neutrally charged at pH 7.4 (see Figure 12 in Chapter 4), and clinically ineffective against common colds. However, this addition is not necessary to preserve a reasonable double blind aspect for a clinical trial.

    Addition of excess strong zinc chelator (1.33 mole citric acid) to zinc gluconate in placebo lozenges is highly recommended, as worsened results may be found, resulting in elimination of the argument by Gwaltney(5) that "zinc don't work, because placebos weren't matched".

    True astringents in placebos are discouraged, as astringents might improve placebo results for several throat symptoms throughout the study and shorten half-lives of placebo-treated colds by a day. As evidence to this effect, beneficial astringent effects might have occurred in the Godfrey and co-worker 1992 trial with astringent placebo lozenges (see Chapter 4.C.3). Osol provides a discussion of astringents and pseudo-astringents.(8) He reports most astringents are salts of zinc, aluminum, manganese, iron, and bismuth, or tannins and polyphenolic compounds, with most being bitter tasting.

    Other substances such as acids, alcohols, phenols, or other related protein-precipitating substances are not generally considered true astringents as they may penetrate cell membranes, while true astringents, such as Zn2+ ions, do not.

    Recommended Placebo Lozenge Formula

    Pseudo-astringent lozenges identical in taste and astringent-like oral feeling can be made using the zinc gluconate plus 1.33 mole citric acid formula of Farr and Gwaltney(5) in otherwise idential lozenges. They are characterized by saliva production, salivary protein precipitation, mouth-feel characteristics, oral dissolution times, blood and urine parameters essentially identical to zinc acetate lozenges. However, placebos may be slightly more tart, or bitter-sweet in flavor, and citric acid additive may cause minor oral mouth-feel side-effects (pseudoastringency). An independent clinical trial using the active lozenges of Farr and Gwaltney as the placebo lozenges in a double-blind, placebo-controlled clinical trial of ZIA 100 zinc acetate lozenges would decisively close the door to Gwaltney's arguements that "zinc don't work".

    Formal taste tests after the manner of Farr and Gwaltney(5) in ill patients should show one or more variation of these general formulations will produce no taste bias in clinical trials.

    Recommended Clinical Trial Protocols

    With use of zinc acetate lozenges, the "every 2 hours while awake" protocol as described in the 1984 Eby study is necessary to retain ZIA values, and is also the best all-around treatment protocol. Lozenges should be of either the standard or advanced design. Patients should be taught to allow slow lozenge dissolution to occur to maximize absorption of Zn2+ ions into mucosal membranes of the mouth and throat. The loading dose should be two lozenges, one-after-another, not two-at-once. Adults and youths over 30 pounds should dissolve one lozenge every two hours while awake after the loading dose. Children under 30 pounds may dissolve 1/2 lozenge every 2 hours while awake, although it appears unlikely to overdose a small child with full dosages (See Chapter 8, Table 16). Patients should be instructed to eat soda crackers or other food if nausea occurs while using zinc lozenges.

    Patients should be instructed to continue treatment every 4 to 6 wakeful hours for a day after the end of the last common cold symptom to help prevent relapse. Patients should not be required to continue full treatment after cessation of symptoms, because headaches may occur from continued treatment in well patients. However, patients should also be instructed to avoid stress and include one or two treatments during the second day after cessation of symptoms as further insurance against relapse.

    The ZIA value of lozenges should be ascertained for each patient at the start of each clinical trial for research purposes directed toward verifying the ZIA/reduction-in-duration theory.

    All clinical trials should be done in multicenter trials where investigators at each center do not know other investigators working on the project. Double checking of all patient data sheets and double verification of all results (perhaps by post-trial interviews of patients) by the trial sponsor should be standard operating procedure. Some researchers, especially researchers specializing in common colds, may reject their own positive findings as unbelievable.

    Clinical trials may use wild colds from patients having had symptoms for no more than 3 days, or colds may be artificially induced using human rhinoviruses and other common cold-causing viruses as desired. Patients with HIV infection, AIDs, acute lymphocytic leukemia, pediatric Hodgkin's disease, and other lymphocyte diseases may be treated in studies addressed specifically at treating colds in such ill patients with expectation of clinical improvement.

    Clinical laboratory tests may include complete blood count, differential leukocyte count, metabolic profile, urinalysis, levels of copper and zinc in serum, urine, and feces, blood pressure, and atomic absorption studies.

    All zinc serum tests should be conducted considering the strong circadian rhythm of zinc. Peak levels occur at about 9:30 AM and lowest values occur at about 8:00 PM, with peak-trough differences of 19 mmg/dL.(9) These differences may be more than the differences found between zinc and placebo treatment. Actual zinc absorption might be assessed using 69mZn with its half-life of 13.9 hours and a gamma energy of 439 Kev.(10)

    Improving Clinical Results

    Experience with many common colds using zinc gluconate lozenge treatment during the 4 years immediately preceding the 1984 study showed results could be improved if certain additional steps were followed. Patients using the "every 2 hour" protocol should be instructed results may be improved if they (a) sleep after first treatment and other treatments when possible; (b) treat at bedtime (especially important as lymph flow ceases during sleep resulting in Zn2+ being held in tissues resulting in higher ZIA values); (c) treat after meals and drink (not before to avoid washing away oral Zn2+ ions); (d) avoid mouthwashes and alcohol; (e) avoid aspirin; (f) avoid antihistamines, decongestants, and other cold remedies; and (g) avoid smoking. Years of experience clearly shows sleeping after use of lozenges is the most valuable of these steps.

    An additional step important in preventing lower airway involvement from heat sensitive viruses such as rhinoviruses is application of heat to the upper back using a heating pad. This step can be used effectively during sleep, particularly when patients lie on their backs with an appropriate heating pad under their shoulders.

    ZIA values of 432 can be obtained by using ZIA 108 lozenges (18 mg zinc in 5-gram advanced design lozenges) once each 30 minutes continuously throughout the wakeful day. This procedure is useful when the patient strongly desires to be completely symptom-free within 24 to 48 hours. This is a maximum-force effort, rarely used for more than the first day, because of the potential for oral tissue irritation.

    Expected Clinical Results from Advanced Design Lozenges

    Results from field use lead the present author to believe nearly all colds can be terminated within a day or two (see Figure 27). The half-life of colds treated with ZIA 108 advanced design lozenges is expected to be 2 days, versus 7.6 days for placebo or no treatment. About 15 percent of patients can be expected to become asymptomatic within 12 hours, and 25 percent can be expected to become asymptomatic within 24 hours.

    Used every half-hour for more than a ZIA 400 effect, results can be improved, perhaps with the majority of patients becoming well within 24 hours. Because clinical evidence for lozenges used to produce a ZIA 400 effect is currently lacking, one can only speculate on the actual statistical outcome. If these values are projected from Figure 19 (see Chapter 5), treatment theoretically produces 7- and 42-day average reductions in duration. One may appear to be a nonsensical statistic because it is so far beyond the 10.8 day average duration of untreated common colds.

    Expected effect of ZIA 100 and 400 lozenges

    Figure 27. Expected effect of ZIA 100 and 400 lozenges.

    Both treatments are expected to cure common colds. Perhaps the "42 day" average reduction can best be interpreted as meaning a much greater fraction will be well on the first day than by normal treatment. Alternatively, ZIA 400 treatment may be interpreted as being excessive, especially if used for more than 1 day. Although the amount of zinc taken on day 1 using the quadruple dosage is higher than the amount using the ZIA 108 protocol, the total amount of zinc taken over the 7-day study period is likely to be less than if zinc is taken using the ZIA 108 protocol.

    Relapses can be prevented by taking a few lozenges on the second and third day and by avoiding stress on the first few days after recovery.

    Termination of colds within hours repeatedly occurs in field usage of ZIA 100 lozenges when lozenges are used more often than normal at the earliest sign of an impending cold. Rapid termination of colds suggests cell membrane stabilization and perhaps antirhinoviral effects are operative. Interferon induction does not appear possible during the first day, as 24 hours were necessary for its induction in laboratory studies. However, interferon induction by the second day along with antirhinoviral effects may keep colds from returning.

    The most likely explanation for near-instantaneous response is membrane stabilization by Zn2+ ions and cell membrane pore closure by Zn2+ ions, as suggested by Pasternak.(11) Pore closure applies to inflammation and mucus-producing cells such as mast and goblet cells, and tissues dry rapidly. Because pore closing occurs instantaneously and is usually permanent, clinical observations may reflect in vitro Zn2+ ion pore-closing activity. Once colds are terminated, colds do not relapse as a general rule, corresponding well with in vitro pore closure results.

    Reduction in facial edema from zinc acetate lozenge treatment of colds is often quite visible, and coincides with patient improvement.

    Viral infections generally depend upon cell-mediated immunity for complete resolution, and there is no reason to believe such would not be true in common cold therapy with lozenges releasing Zn2+ ions.

    However, the zinc lozenge effect works equally well in T-cell immunosuppression induced by chemotherapeutic agents in the treatment of childhood acute lymphocytic leukemia. Zn2+ ions, perhaps through cell membrane stabilization, might substitute for several roles usually played by T-cell lymphocytes. The potential benefits to HIV and AIDS patients are obvious -- and important.

    Full Circle

    Revisiting the original incident leading to this line of research is merited. Consider the case of the 3-year-old girl suffering from acute lymphocytic leukemia who retained a crushed 50 mg zinc (zinc gluconate) tablet in her mouth while she napped for 2 hours and awoke to find her cold was gone without relapse.

    The estimated ZIA value for the single treatment is 461. The dosage was 50 mg zinc gluconate yielding 30 percent of its zinc as Zn2+ ion. The dosage was absorbed over the 120-minutes nap period for one dose in a single day. Saliva production is estimated at 10 grams.

    Saliva may have been less as the child had undergone 500 rad cranial radiation for two weeks before her cold, which damaged the parotid glands resulting in a dry mouth.

    Reconsidering Fick's law and mucosal membrane thicknesses, one might suspect a 25-pound child would have thinner oral mucosal membranes, perhaps less than one-half adult thickness, doubling the rate of absorption. Considering a dry mouth and thinner oral mucosal membranes suggests raising the ZIA calculation to an estimated ZIA value of over 1000.

    Considering the zinc dosage to body weight ratio, a 50-mg zinc dose in a 25-pound child is equivalent to a 300- to 400-mg zinc dose in an adult. These total zinc doses are not toxic in small children and are approached by nursing infants (see Chapter 8, Table 16).

    After considering the evidence in terms of ZIA, doubt that a single lozenge could terminate the child's cold in the manner described is more easily dispatched. In actuality, the original finding now seems not only reasonable but expected. As lymph circulation stops during sleep, retention of Zn2+ ion in infected tissues is highest then.

    Consequently, benefit in terms of more rapid recovery from sleeping after use of lozenges and a bedtime use of a lozenge are explained. Often patients awake after a night's sleep with only residual nasal congestion and stuffiness. When congestion is cleared by blowing the nose, common cold symptoms often do not return.

    Expected Side Effects and Contraindications

    The side effects from advanced design ZIA 92 to 138 lozenges are expected to be essentially non-existent. No oral side effects, other than mild oral drying, are expected from the great majority of patients. A few patients may experience an occasional mild aftertaste that does not occur consistently and is caused by unknown factors, perhaps related to the patients' current zinc status.

    Side effects from considerably higher ZIA value lozenges can occur. After taste-testing nearly 1000 flavor-masked formulations of zinc gluconate, zinc acetate, and other zinc compound lozenges over 6 years and reviewing many clinical and field tests in hundreds of patients with common colds since 1979, four side effect have been determined to be expected when lozenges with high ZIA values are used.

    First, headaches can occur from over-use of ZIA 160 to 200 lozenges in the absence of common cold symptoms during flavor testing. The headaches respond well to ibuprofen (600 to 800 mg doses). Why ZIA 160 to 200 lozenges cause headaches in patients without common cold symptoms but terminates headaches in patients with common colds is unknown, but probably relates to higher retention of Zn2+ ions in tissues of patients without common cold symptoms. Cell membrane permeability of facial, oral, and nasal tissues may be much higher in patients with common colds (observe their edematous faces), and Zn2+ ions may be rapidly washed out of those tissues. In patients without colds, membrane permeability is lower and Zn2+ ions may accumulate to high levels, perhaps adversely affecting prostaglandin synthesis or its metabolism. This activity can make flavor-testing work time-consuming (to avoid headaches) and can cause taste testers to give warnings about headaches not applicable to ill patients. The propensity to develop headaches increases with ZIA values of the lozenges and frequency of use.

    Headaches can also occur with continuous use of standard design ZIA 150 lozenges for a ZIA 600 effect in the absence of a common cold. Headaches may be caused by saccharin or a combination of saccharin and flavors. Several taste-testers noticed headaches resulting from use of standard design lozenges containing saccharin, although they did not develop headaches using otherwise identical lozenges without saccharin.

    None of the clinical trials of zinc lozenges showed zinc to cause headaches in patients with common colds. However, close examination of Tables 2 and 3 in Chapter 4 show headache symptoms fell to zero in the zinc-treated group on days 4 and 5 but rose slightly in days 6 and 7. Whether these observations are caused by patients continuing zinc treatment after cessation of common cold symptoms or they are random headaches is unknown. Regardless, headaches may occur if patients use zinc lozenges too long after cessation of symptoms.

    Second, nausea is a randomly occurring side effect of zinc lozenges observed mostly in women. On occasion even small doses of zinc, whether used as a lozenge or as a dietary supplement, cause some women to become nauseated, occasionally to the point of vomiting (see Table 4 in Chapter 4). This phenomenon is not an exclusive property of zinc acetate lozenges but a property of orally administered zinc. Patients should always be advised to use lozenges after eating and drinking to avoid nausea, if they are concerned about nausea. Eating soda crackers -- and food generally -- helps relieve nausea, and should be recommended to patients suffering from lozenge-induced nausea. In those rare patients knowing they will vomit if they ingest zinc, treatment of colds with zinc should be avoided or performed cautiously. Patients prone to vomiting should be warned not to drive a motor vehicle or perform dangerous tasks while using zinc acetate lozenges.

    Third, oral irritation from continuous or excessive use of strong zinc acetate lozenges may occur but not nearly to the extent resulting from use of zinc gluconate lozenges. Tongue and cheek tissues seem most affected, and those tissues can become temporarily sore. However, in no case has oral irritation been too severe to discontinue treatment using ZIA 100 lozenges, even continuously for a ZIA 400 effect. However, ZIA 150 lozenges used continuously (ZIA 600) may cause oral irritation to a degree prompting some patients to withhold occasional treatments during the 1-day treatment course.

    Patients have fallen asleep with zinc gluconate lozenges in their mouths resulting in a painless, raised white spot in the cheek tissue. The white spot has not been noticed with zinc acetate lozenges, even when patients have fallen asleep with a zinc acetate lozenge in the mouth. Severe tissue irritation and the raised white spot are most likely caused by cell membrane permeation of zinc gluconate-hydroxide at pH 7.4 (see Figure 1, Chapter 1), and not from Zn2+ ions from zinc acetate. Spots from zinc gluconate lozenges subsided within a day without residual tissue harm.

    Fourth, temporary alteration of food taste is a common occurrence and is generally considered a nuisance rather than a side effect. Occasionally, the alteration of taste extends to the taste of zinc lozenges. Occasionally, a patient might find zinc acetate lozenges to be slightly bitter, metallic, or somewhat unpleasant, while the same patient normally has no complaint about zinc acetate lozenges. Drinking or eating usually results in improved taste sensation within a few minutes.

    One, and only one, volunteer reported a zinc acetate lozenge to have a dreadful taste, even while other volunteers were finding the taste of identical lozenges from the same batch to be pleasant or good. Using different lozenge batches produced the same perplexing results. All food had begun to have a very objectionable taste to this volunteer. The dreadful taste of zinc acetate lozenges may have been zinc induced-hypogusia, or may have been coincidental hypogusia. If the observation was zinc-induced hypogusia, such would be quite strange, as many cases of hypogusia are caused by zinc deficiency, not zinc excess. In this volunteer, taste aberration was also associated with a dental sensitivity and clinical depression. The relationship between these and objectionable lozenge taste is unknown and did not occur in any other patient with dental sensitivity. The volunteer's taste problem disappeared upon desensitization of the patient's teeth with commercial potassium nitrate-based dental desensitizers and cessation of depression. Zinc deficiency has been observed in clinical depression and may be the cause of depression-related taste abnormalities.

    Use of Zinc Acetate Lozenges to Treat Upper Respiratory Allergy

    Zinc applied to the nasal nares either with or without electrical stimulation has a history of use dating back to the 19th century (see Chapter 2). Clearly, Zn2+ ions inhibit the release of histamine from mast cells. The use of zinc acetate lozenges to control nasal allergy temporarily is new and effective. A single ZIA 100 to 150 lozenge used early in the morning often terminates or greatly reduces symptoms for several hours to a day. Repeated use as needed appears beneficial and seems to cause no harm.

    Zinc Acetate Lozenges and Mononucleosis

    Continuous use of ZIA 50 zinc acetate lozenges (resulting in a ZIA 200 effect) while awake as treatment for severe tonsillitis caused by Epstein Barr virus as mononucleosis in a 17-year old girl produced rapid (a) reduction in oral and nasopharyngeal inflammation; (b) elimination of bilateral shaggy gray tonsillar exudate; (c) elimination of fever; (d) improvement in patient's feeling of well-being; (e) elimination of supraorbital edema; (f) elimination of malaise, and fatigue; (g) return to normal vocalization; (h) elimination of anorexia; and (i) atrophy of extremely swollen tonsils to less than normal size. All benefits occurred within 1 to 3 days of treatment initiation.

    After the first lozenge, the patient resolutely and continuously used zinc acetate lozenge treatment, refusing codeine, ibuprofen, and lidocaine. Corticosteriods for severe airway obstruction were not given in preference to the beneficial effects reported from zinc acetate lozenges. Antibiotic for concurrent strep throat was continued for the normal course. Splenomegaly, lymphadenophy, hepatomegaly and other complications did not occur. No side effects to treatment nor recurrence of diseases occurred. The patient was able to return to school on the fourth day after diagnosis (which occurred on the 4th day of illness) and was sufficiently well to resume athletic activities on the fourteenth day after diagnosis. This anecdote should stimulate others to investigate the antiviral properties of Zn2+ ion against Epstein Barr virus and to conduct clinical trials of the effects of zinc acetate lozenges in treatment of mononucleosis.

    As zinc acetate releases Zn2+ ions which are antiviral to several herpes simplex viruses (see Chapter 2), Zn2+ ions also may be antiviral to the Epstein Barr virus, another member of the herpes family. However a thorough literature search revealed no evidence of anti-Epstein-Barr activity by Zn2+ ions.

    If Zn2+ ions are antiviral to Epstein-Barr viruses, zinc acetate lozenge treatment of mononucleosis might prevent Burkitt's lymphoma. Burkitt's lymphoma is associated with Epstein-Barr virus in Africa, Turkey, and other locations where dietary zinc is often inadequate, but rarely in countries such as the United States where zinc nutrition is normally adequate. As Burkitt's lymphoma is a serious and difficult-to-treat disease, immediate investigation of the effects of zinc acetate lozenges in preventing Burkitt's lymphoma through treatment of mononucleosis is warranted.

    Concluding Remarks

    The reports of divergent results of various zinc lozenges for common colds are analyzed in this handbook. Each individual report has been shown to illustrate a facet of the over-all effects of zinc lozenges. No single report represents the universe of possible effects in treating colds by all other zinc lozenges. Lozenges releasing Zn2+ ions provide dose- and time-dependent positive results, and lozenges releasing neutral or negatively charged zinc species do not. The distinction must be drawn between lozenges providing Zn2+ ions and lozenges not providing Zn2+ ions. These differences are crucial to the discovery and must not be overlooked or discounted. The relationship between efficacy, as measured in reduction in duration of common colds, is directly related to zinc ion availability (ZIA), which depends upon the availability of Zn2+ ions and the time ions are applied to the oral mucosa.

    All clinical studies correlate well with each other when the studies are considered from the perspective of zinc ion availability (ZIA). In the original 1984 study, and separately in the Al-Nakib and co-worker study, no patient complained of lozenge bitterness, as lozenges contained no soluble sweeteners complexing with zinc to form bitterness.

    Differences in ZIA are a much larger distinguishing feature between successful trials and unsuccessful trials than the placebo-unblinding hypothesis presented by Gwaltney and Farr. Consequently, there is no evidence to support results-impairing placebo-unblinding effects in the results of the original 1984 study, or the one by Al-Nakib and co-workers.

    After considerable study, the present author suggests 16 to 23-mg of zinc from zinc acetate dihydrate in advanced design 5 gram compressed lozenge (ZIA 100 to 185) is the proper dosage range for treating common colds. In well persons, the higher dosage may seem too astringent and too strong. However, in patients ill will a common cold the 23-mg zinc dosage seems much lower, perhaps because the oral, facial and nasal tissues are so much more permeable. This difference in taste perception incorrectly caused other common cold researchers taste-testing the original 1984 zinc gluconate lozenges while they were well to allege placebo-unblinding in the original 1984 Eby and co-worker double-blind, clinical study.

    In retrospect, some readers may prefer a figure graphically showing the fraction of zinc present as solution Zn2+ ions at physiologic pH for the several zinc compounds studied. Critical fractions of zinc as Zn2+ ions shown below are from original source data as presented throughout this handbook.

    Fraction zinc as zinc ion by pH for severl zinc compounds used in common cold research

    Figure 28. Fraction of zinc as Zn2+ ions at pH 7.4 as function of first stability constant.

    The value of K1, the first stability constant, is greatly different for each zinc compound. The amount of Zn2+ ion at pH 7.4 drops precipitously for zinc compounds having stability constants greater than log K1 = 1. The precipitous drop results from the stability constant being a part of divisor of the equation used to determine the concentration of Zn2+ ions. See Calculating Availability of Zn2+ ions in Chapter 1 for details. With a hypothetical zinc compound having a first stability constant of log K1 = 2, treatment of common colds would require nine 160-mg doses of zinc (moderately toxic dosage) daily to provide the same amount of zinc ions as 9 doses daily of zinc acetate having 16 mg zinc each. Similarly, nine 16,000 mg doses of zinc from zinc aspartate (near LD50 dosage) would be needed For sake of clarity, stability constants below zero are not shown, but they can exist. Common cold treatment requires zinc ions, not total zinc compound. For safety, efficacy, and palatability reasons, zinc compounds having a first stability constant over 100 (log K1 over 2) are unusable in common cold lozenges.

    Low mouth-nose BCEC resistances suggest limited immunity to upper respiratory tract infections. Exceedingly low resistance appears associated with chronic nasal drainage and/or allergies. Extremely high resistance values appear associated with strong resistance to nasal infections and allergy. Hypothesized relationships between respiratory disease susceptibility and electrical resistance remain unproven and may warrant further investigation. Verification may demonstrate an a priori means to determine a patient's susceptibility to those common cold viruses for which antibody is low or absent, and for whom allergic desensitization might not benefit, but supplemental oral or topical zinc (using zinc acetate lozenges) might be of benefit.

    This handbook's end is not the end of the story of using zinc lozenges for common colds, but rather the starting point for a United States Food and Drug Administration New Drug Application (NDA) so commercialization of patented, properly manufactured, advanced design zinc acetate lozenges as treatment for common colds can begin. The NDA is not the end of the story either -- but the beginning of the end for long periods of illness from common colds.

    Even if a high-tech competing product such as Gwaltney's patented "interferon cocktail" (a mixture of interferon to stop viral replication, and two anti-inflammatory agents, ipratropium and naproxen)(12) arrives on the scene, the likelihood of it being as safe, as effective, and as inexpensive as ZIA 100 to 185 zinc acetate lozenges is extremely remote, and is probably impossible.

    Consequently, a pharmaceutical company wishing to have a monopoly on a method to shorten the duration of colds, or cure common colds, needs to re-examine zinc lozenges, and particularly advanced design zinc acetate lozenges.

    The second edition of this handbook will include the results of comprehensive flavor-masking and placebo selection studies, new clinical evidence for efficacy, the results of a New Drug Application, and other features and findings of the ongoing research.

    Chapter 9 References

    1. Briggs J, Finch P, Matulewicz MC, Weigel H, 1981, Complexes of copper (II), calcium, and other metal ions with carbohydrates: Thin-layer ligand-exchange chromatography and determination of relative stabilities of complexes. Carbohydrate Research. 97:181-188.

    2. Karlowski TR, Chalmers TC, Frenkel LD, et al. 1975. Ascorbic acid for the common cold: A prophylactic and therapeutic trial. Journal of the American Medical Association. 231:1038-1042.

    3. Pauling L. Vitamin C and the Common Cold. Journal of the American Medical Association. 971;216:332.

    4. Shult PA, Dick EC, Olander D, et al. 1990. Diminished rhinovirus (RV) illness severity correlates with increased leukocyte ascorbic acid (AA) Levels. Thirtieth Interscience Conference on Antimicrobial Agents and Chemotherapy, Atlanta, GA, Abstract 1285.

    5. Farr BM, Gwaltney JM. Zinc gluconate for the common cold: An evaluation of placebo matching. Journal of Chronic Diseases. 1987;40:875-879.

    6. Eby GA, Davis DR, Halcomb WW. Reduction in duration of common cold symptoms by zinc gluconate lozenges in a double blind study. Antimicrobial Agents and Chemotherapy. 1984; 25:20-24.

    7. Al-Nakib W, Higgins PG, Barrow I. et al. Prophylaxis and treatment of rhinovirus colds with zinc gluconate lozenges. Journal of Antimicrobial Chemotherapy. 1987;20: 893-901.

    8. Osol A. Astringents and antiperspirants. In: Osol A. ed. Remington's Pharmaceutical Sciences, 16th Edition. Easton:Mack Publishing Co. 1980;720-722.

    9. Markowitz ME, Rosen JF, Mizruchi M. Circadian variations in serum zinc (Zn) concentrations: correlation with blood ionized calcium, serum total calcium and phosphate in humans. American Journal of Clinical Nutrition. 1985;41:689-696.

    10. Molokhia M, Sturniolo G, Shields R, et al. A simple method for measuring zinc absorption in man using a short-lived isotope (69mZn). The American Journal of Clinical Nutrition. 1980;33:881-886.

    11. Pasternak CA. A novel form of host defense: membrane protection by calcium and zinc ions. Bioscience Reports. 1987;7:81-91.

    12. Radetsky P. Cold Front - What's new and what works. American Health. 1993;12(8):56-62.









    Appendix: Principle Articles

    Prophylaxis and treatment of rhinovirus colds with zinc gluconate lozenges (Great Britain Medical Research Centre Common cold Unit - 1987)

    Reduction in Duration of Common colds by Zinc Gluconate Lozenges in a double-Blind Study (Eby et al. 1984)






    How Handbook for Curing the Common Cold was Conceived

    Handbook for Curing the Common Cold is finally compete. How was the handbook conceived? From where did the insight come? The answers are so strange most readers will only shake their head in amazement, and disbelief. However, the pure truth, no matter how strange, is important and should be recorded. Below is the author's strange but true story of discovery, and its painful origin.

    The author, Mr. George A. Eby, of Austin, Texas, was forced into biomedical research on Valentine's day in 1979 when his 3-year old daughter, Karen, was diagnosed with acute T-cell lymphocytic leukemia. On March 5, 1979, she had a bone marrow leukemic blast count of zero. One month after diagnosis, a massive proliferation of healthy reticulocytes (young red blood cells) added more evidence that her recovery was occurring at an astonishingly rapid rate. Her oncologist, Paul Zeltzer, M.D., of the University of Texas Health Science Center at San Antonio, remarked, "Mr. Eby, her blood picture has set a new standard in improvement. I wonder why. Perhaps one of those enormous vitamin and mineral supplements you have been giving her beneficially interacted with our chemotherapy. You might look into that idea, because if you stop the operative supplement, she might get worse. Who knows, and I am only guessing, but it would keep you busy."

    At first Eby felt completely unable to cope with the awesome task ahead as he was not educated as a physician or scientist. Rather, Eby had a B.S. in mathematics from the University of Texas at Pan American. After a stint on the Apollo Project at Houston's NASA, he changed career fields, and graduated from Texas A&M University in 1970 with a masters degree in city planning. He practiced city planning in several Texas cities until 1979. Without any doubt, his academic and professional background was completely inadequate for the task at hand.

    Using his modest mathematical and planning ability, he accepted the challenge of identifying the mystery nutrient. Eby developed a plan to sort through the many possible interactions. He used a matrix with vitamins and minerals on the Y-axis, and each of Karen's conditions on the X-axis. On the X-axis were frequent colds, primary immune anergy, absence of weight gain, extremely foul body odor, lethargy, anorexia, anemia, radiation therapy, leukemia, remissions, drug interactions and other signs and symptoms of leukemia.

    After several months of library research, the matrix filled in sparsely and randomly except for the nearly full zinc line. Eby consequently focused his attention squarely on zinc as the nutrient most likely to have had the adjuvant action on Karen's chemotheraphy. Children on immunosuppressive chemotherapy often have severe common colds, so fighting colds became another priority. Taking zinc supplements seemed no more harmful, and no less reasonable than taking Vitamin C because these nutrients, as well as others, are needed by the primary T-cell immune system to fight cancer, leukemia, and viral infections. Unfortunately, giving dietary supplements of vitamin C, zinc and other nutrients did not seem useful in fighting Karen's colds.

    About four months after Karen's diagnosis of leukemia, she developed a particularly severe cold. Her throat was swollen and too painful for her to swallow a zinc gluconate (50 mg zinc) tablet. Eby asked Karen to chew the tablet instead. Karen was too exhausted to chew for long, and she soon went to sleep with most of the crushed tablet remaining in her mouth. Several hours later, Karen came into the living room playing with her toys, saying, "I'm all well, Mom!" Karen, still immunosuppressed from chemotherapy, was completely over her cold. Her cold did not return, even though no subsequent treatment was given. The effects of zinc gluconate lozenges on Karen's colds were impossible for Eby to ignore.

    Eby's fascination with zinc and zinc gluconate lozenges increased. Later, clinical trials verified that zinc gluconate lozenges shortened common colds. However, they lacked commercial utility because their taste was insufficiently pleasant. Fifteen years after Karen's diagnosis of leukemia, Handbook for Curing the Common Cold documents one of the most amazing, and highly neglected powers of Zn2+ ions.

    The big question is, will zinc acetate lozenges as the cure to the common cold, the HOLY GRAIL OF MEDICINE, become widely accepted?










    Finally, A Real Cure for Common Colds

    Fifteen years to the day in development, Handbook for Curing the Common Cold - The Zinc Lozenge Story is the first book to convincingly show zinc lozenges to be the real cure for common colds. The zinc lozenge cure was first described in a technical paper published by George Eby and others at the University of Texas in Austin, Texas, in 1984. It showed zinc gluconate lozenges to be far more effective than Viamin C, chicken soup, and other over-the-counter treatments, shortening colds by an average of 7 days!

    The world famous Medical Research Council Common Cold Unit led by David A. J. Tyrrell verified the Austin group's findings in 1987. Since then, several attempts to replicate the positive findings were made by others using weaker and chemically different zinc lozenges. The weaker and different formulations failed, and publication of the negative results created considerable controversy.

    All of the reports, positive and negative, demanded the careful re-analysis presented in this handbook to place them in proper perspective. Actually, results were not in conflict at all, rather each report showed a different facet of the puzzle. When the completed puzzle is viewed, it simply shows Zn2+ ions from zinc lozenges shorten colds in a dose and time dependent manner, as any skilled pharmacologist might expect.

    Using all available data, Handbook for Curing the Common Cold -- The Zinc Lozenge Story establishes means -- zinc ion availability (ZIA) -- to make sense out of strange data, and provides predictive power on the efficacy of experimental zinc lozenges against common colds.

    Don't miss the forewords from the University of London and the Medical Research Council Common Cold Unit!

    Handbook for Curing the Common Cold -- The Zinc Lozenge Story clearly shows:

    • Zinc lozenges must release hydrated Zn2+ ions to shorten common colds.

    • Zn2+ ions stop the replication of rhinoviruses, the main cause of common colds.

    • Zn2+ ions strongly induce production of interferon, an antirhinoviral and cell membrane protective agent.

    • Cell membranes are stabilized by Zn2+ ions allowing the nose to dry quickly.

    • Pleasant tasting zinc acetate lozenges release Zn2+ ions.

    • A U. S. Food and Drug Administration approved New Drug Application is needed market zinc acetate lozenges as means to cure common colds.




    ISBN 0-9638967-0-9

    Handbook for Curing the Common Cold - The Zinc Lozenge Story


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