Update on pharmacologic options for smoking cessation treatment.

Although the proportion of the adult population in the United States that smokes has decreased steadily, the rate of successful quit attempts is still low. Smokers develop nicotine dependence that resembles other addictions, and may require multiple attempts and long-term treatment to sustain abstinence. Currently available first-line agents for smoking cessation therapy include nicotine replacement therapy, which is available in several formulations, including transdermal patch, gum, nasal spray, inhaler, and lozenge; bupropion, an atypical antidepressant; and varenicline, a partial agonist of the alpha(4)beta(2) nicotinic acetylcholine receptor that was recently developed and approved specifically for smoking cessation therapy. Second-line agents are nortriptyline, a tricyclic antidepressant agent, and clonidine, an antihypertensive drug. With the exception of varenicline, which has been shown to offer significant improvement in abstinence rates over bupropion, all of the available treatments appear similarly effective. However, the adverse event profiles of nortriptyline and clonidine make them more appropriate for second-line therapy, when first-line treatments have failed or are not tolerated. Rimonabant, a cannabinoid-1 receptor antagonist that was being developed for smoking cessation, received a nonapprovable letter from the FDA in 2006 and there is no further information as to whether development for this indication is continuing for this agent. Nicotine vaccines are under investigation and offer promise, especially for relapse prevention. Ultimately, selection of pharmacologic agent should be based on the patient's comorbidities and preferences, as well as on the agent's adverse event profile.