The drug varenicline shows effectiveness in helping smokers quit and abstain from smoking when compared to placebo and the smoking cessation medication bupropion, according to three studies in the July 5 issue of JAMA.
Although nearly 41 percent of smokers try to quit smoking each year, relapse is common, and only about 10 percent achieve and maintain abstinence. The negative effects of nicotine withdrawal account, in part, for low success rates, according to background information in the article. Approved pharmacotherapies to treat nicotine dependence (e.g., nicotine replacement therapy and bupropion) have had important, but moderate efficacy, with reported rates of quitting generally twice those of placebo. Additional and more effective therapies are needed.
David Gonzales, Ph.D., of Oregon Health & Science University, Portland, and colleagues with the Varenicline Phase 3 Study Group evaluated the efficacy of varenicline compared with placebo and sustained-release (SR) bupropion in generally healthy adult smokers. Varenicline is a non-nicotine drug that is thought to be beneficial for smoking cessation by stimulating the release of the chemical dopamine in the brain to reduce craving and withdrawal while simultaneously blocking the reinforcing effects of smoked nicotine. Most other smoking cessation pharmacotherapies are nicotine replacement products.
Participants in the study were 1,025 smokers (10 cigarettes or more per day) with fewer than 3 months of smoking abstinence in the past year. The randomized, double-blind, phase 3 clinical trial was conducted at 19 U.S. centers from June 2003 to April 2005. Participants were randomly assigned to receive brief counseling plus either varenicline twice per day (n = 352), bupropion SR twice per day (n = 329), or placebo (n = 344) orally for 12 weeks, with 40 weeks of nondrug follow-up.
The carbon monoxideconfirmed 4-week continuous abstinence rate for weeks 9 th
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