Effects of a 2.5-mg silver acetate lozenge on initial and long-term smoking cessation

Silver acetate over-the-counter products, such as gum, lozenge, and spray, produce an aversive metallic taste when combined with cigarette smoke. Hence, they hold promise of serving as an effective smoking deterrent, one that may be used on a self-help basis.

Five hundred adult smokers, male and female, were assigned randomly to one of two experimental conditions, 2.5-mg silver acetate lozenge and placebo lozenge. A double-blind study of the effects of a 2.5-mg silver acetate lozenge on initial (3 weeks) and long-term (12 months) smoking cessation was carried out.

About 90% of the subjects (n = 500) reported using the lozenge (silver acetate or placebo) for smoking cessation, and they used about five lozenges per day. Over 70% of the quitters (n = 70) reported using the lozenge on an as-needed basis for relapse prevention. The overall objectively verified quit rates for subjects assigned to the silver acetate and placebo conditions at Visit 3 (3 weeks) were 17% (n = 42) and 11% (n = 28), respectively, a difference which approached statistical significance (P = 0.071). When the analysis was restricted to subjects who used the product, a statistically significant difference (P < 0.05) in initial smoking cessation emerged (26%, n = 37 vs 16%, n = 23) for subjects assigned to the silver acetate and placebo conditions. At 12 months follow-up, 26% (n = 11) of initial quitters in the silver acetate condition and 32% (n = 9) of the quitters in the placebo condition were abstinent. This difference was not statistically significant.

The study demonstrated modest efficacy for the effect of the 2.5-mg silver acetate lozenge on initial smoking cessation for the subset of subjects who used the product as recommended. We failed to demonstrate efficacy of the lozenge for long-term relapse prevention. Additional research on the efficacy of the 2.5-mg silver acetate lozenge and long-term abstinence in general appears warranted.