Human abuse liability of the smoking cessation drug varenicline in smokers and nonsmokers.

Varenicline is an alpha(4)beta(2) nicotinic acetylcholine receptor partial agonist developed as an aid for smoking cessation. This study evaluated varenicline's potential for abuse by smokers (n = 23) and nonsmokers (n = 22). The study used a randomized, double-blind, placebo-controlled, double-dummy crossover design with five treatment periods: 15 and 30 mg amphetamine, 1 and 3 mg varenicline, and placebo. Following each treatment, the participants were assessed on aspects relating to potential abuse of the drug (e.g., drug liking, drug high, and drug monetary value). The positive effects measured for 3 mg varenicline were similar to those for the placebo, and significantly lower than those for amphetamine in both smokers and nonsmokers. Unpleasant effects were reported for 3 mg varenicline in both participant groups. For 1 mg varenicline, the overall patterns were similar, with the exception that the nonsmokers group showed some small positive effects balanced by some negative effects when compared with the effects of placebo. These findings lead to the conclusion that varenicline is unlikely to be abused.