Silver acetate for smoking cessation.

Silver acetate produces an unpleasant taste when combined with cigarettes, thereby producing an aversive stimulus. It has been marketed in various forms with the aim of extinguishing the urge to smoke, by pairing the urge with an unpleasant stimulus. The aim of this review was to determine the effectiveness of silver acetate products (gum, lozenge, spray) in promoting smoking cessation. We searched the Cochrane Tobacco Addiction Group specialised trials register. Most recent search was in July 2012. We included randomised trials of silver acetate for smoking cessation with reports of smoking status at least six months after the beginning of treatment. We extracted data in duplicate on the type of subjects, the dose and form of silver acetate, the outcome measures, method of randomisation, and completeness of follow-up.The main outcome measure was biochemically validated abstinence from smoking after at least six months follow-up in patients smoking at baseline. Subjects lost to follow-up were counted as continuing smokers. Where appropriate, we performed meta-analysis using a fixed effects model. Two studies provided long-term follow-up data on patients randomised to silver acetate or placebo. In one of these studies, there was a third arm, randomised to 2mg nicotine gum. The pooled risk ratio for quitting for silver acetate vs placebo was 1.04 (95% confidence interval 0.69 to 1.57). Existing trials show little evidence for a specific effect of silver acetate in promoting smoking cessation. The confidence intervals for the ratio are quite wide. However, the upper limit of the confidence intervals for a positive effect equates to an absolute increase in the smoking cessation rate of about 4%. Any effect of this agent is therefore likely to be smaller than nicotine replacement therapy. The lack of effect of silver acetate may reflect poor compliance with a treatment whose rationale is to create an unpleasant stimulus.