MECAMYLAMINE DOES NOT PRECIPITATE WITHDRAWAL IN CIGARETTE SMOKERS

Mecamylamine is an antihypertensive that acts via nicotinic antagonism and has been suggested as an aid in smoking cessation. Nicotine depen dent patients may not accept mecamylamine if it precipitates withdrawa l, as it does in nicotine dependent rats. This study examined mecamyla mine's effects using procedures designed to measure precipitated withd rawal symptoms in humans, Ten cigarette smokers (mean of 37.5 cigarett es/day) and ten non tobacco-using subjects participated in three 6-h s essions. After a 2-h baseline period in which smokers smoked one cigar ette every 30 min, oral mecamylamine (0, 10, or 20 mg randomly ordered across sessions) was administered (double-blind), No smoking was allo wed for the remainder of the session. Mecamylamine reduced blood press ure and increased heart rate relative to placebo in both the smokers a nd the non-tobacco users. No reliable direct subjective effects of mec amylamine were observed, Smokers' subjective reports of cigarette crav ing and tobacco withdrawal increased, and DSST performance was disrupt ed over the last 4 h of each session. Effects were independent of dose (placebo versus active), These results suggest that up to 20 mg mecam ylamine will nor precipitate nicotine withdrawal and that this medicat ion would be acceptable for use in smoking cessation.