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.
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.
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.
Zinc Ion Availability