Zinc Lozenges: Cold Cure or Candy? Solution Chemistry Determinations

Abstract

Common colds were shortened by 7 days in a 1984 clinical trial using zinc gluconate throat lozenges each 2 h. Between then and 2004, 10 other double-blind, placebo-controlled clinical trials showed widely varying results. This re-analysis of these trials presents solution chemistry methods to elucidate differences in efficacy. Statistically significant correlation was shown between total daily dosages of positively charged zinc species and reductions in median (p ¼ 0.005) and mean duration (p < 0.02) of common colds in these trials.

Abstract

“…Zinc gluconate releases 72% iZn, zinc gluconate glycinate releases <57% iZn, while zinc gluconate citrate and zinc citrate and zinc orotate release 0% iZn (Eby 2004). Computation of metal speciation is complex and requires the use of the US National Institute of Technology (NIST) solution chemistry data bases and the skills of solution chemists.…”

“…Computation of metal speciation is complex and requires the use of the US National Institute of Technology (NIST) solution chemistry data bases and the skills of solution chemists. Guy Berthon, PhD, retired Directeur de Recherche CNRS Laboratoire de Chimie Bioinorganique Médicale, Université Paul Sabatier, Toulouse, France and editor of "Handbook of Metal-Ligand Interactions in Biological Fluids -Bioinorganic Medicine" performed critical zinc speciation computations, and they have been published (Eby 2004). The sum of all positively charged zinc species used in clinical trials of zinc lozenges for common colds is termed iZn.…”

“…While lozenges that had little or no iZn produced no benefits, lozenges having a daily iZn value of 80 (equivalent to 10 mg iZn lozenges used eight times per day) shortened colds by 4 days, and lozenges having a daily iZn value of 150 (equivalent to 18 mg iZn lozenges used 8.3 times per day) shortened colds by 5 to 7 days (Eby 2004;Eby 2008). Daily iZn intake from lozenges was found to be directly associated with reductions in durations of common colds by two measures: median (n=14, r= 0.772, P=0.0012) and mean (n=13, r=0.813, P= 0.0007) durations.…”

Zinc lozenges may shorten common cold duration

“…Second, the composition of zinc lozenges has varied and some of them contained substances that form complexes with zinc ions. Therefore, it is possible that some of the negative findings are explained by lozenges that do not release zinc ions [9,10]. Finally, dose dependency is a basic concept of pharmacology, and the negative findings in some studies might be explained by a low total daily zinc dose.…”

“…A dose-response relationship is a more sensible explanation for such a divergence. The great effect of zinc acetate is explained by the lack of complex formation between these ions [9,10].…”