Bupropion: pharmacological and clinical profile in smoking cessation

Abstract

Chemistry, pharmacokinetics, pharmacology, clinical efficacy, adverse effects and dosage of bupropion hydrochloride (BP), an aminoketone antidepressant used in smoking cessation, are reviewed. The nicotinergic acetylcholine receptors are inhibited at clinically relevant concentrations of BP. BP does not inhibit monoamine oxidase, and it has minimal inhibitory effects on presynaptic noradrenaline and dopamine uptake. BP is rapidly absorbed after oral administration and demonstrates biphasic elimination with an elimination half-life of 11 - 14 hours. BP is extensively metabolized by oxidation and reduction to at least 6 metabolites, 2 of which may be active. The plasma levels of the erythro-amino alcohol of BP correlate with several side effects such as insomnia and dry mouth. Efficacy of BP(SR) in smoking cessation has been examined in several double-blind, randomized trials in which daily doses of 150 or 300 mg have been administered for 7 or 9 weeks. In addition, 1 study examined the combination of BP(SR) plus nicotine patch. The point prevalences of stopping smoking reached values between 21.2 and 38%, but they did not exceed those after nicotine replacement therapy alone. Long-term administration (52 weeks) of BP did not improve abstinence compared with placebo after a 2-year follow-up period. Thus, the efficacy of BP in smoking cessation is comparable to that of nicotine replacement therapy. However, BP possesses a broad spectrum of infrequent adverse effects and interferes with the degradation of several drugs such as tricyclic antidepressants, beta-recpetor blocking agents, class Ic-antiarrhythmics etc. As the risk-benefit ratio of BP is smaller than that of nicotine replacement, BP should be considered as a second-line treatment in smoking cessation.