Varenicline: A Novel Nicotinic Receptor Partial Agonist for Smoking Cessation

Abstract

Objective: To review the pharmacology, pharmacokinetics, clinical efficacy, and safety of varenicline, a selective partial nicotinic receptor agonist for smoking cessation. Data Sources: Primary literature and review articles were obtained via a MEDLINE search (1966–January 2007) using the key terms smoking cessation, nicotinic receptor, tobacco, and varenicline. Additional studies and abstracts were identified from the bibliographies of reviewed literature. Study Selection and Data Extraction: Available English-language literature, including abstracts, preclinical and clinical trials, and review articles were identified. Six randomized, placebo-controlled trials were evaluated to determine varenicline's efficacy for smoking cessation. Data Synthesis: Varenicline is a partial agonist selective for the α4β2 nicotinic receptor. Varenicline has been compared with placebo and sustained-release (SR) bupropion in randomized, double-blind, controlled trials. These trials found varenicline to have more successful 4 week continuous quit rates compared with both placebo and bupropion SR. One study reported a significantly increased continuous abstinence rate with varenicline versus bupropion SR; however, 2 other studies found no difference between varenicline and bupropion SR. To date, dose-dependent nausea is the most frequent adverse effect associated with varenicline; this may be limited with proper dosage titration. Conclusions: Increased cessation rates in comparison with placebo and, possibly, bupropion SR, as well as limited safety concerns, suggest that varenicline may have a role as another first-line therapy for smoking cessation.