Smokers who use the prescription-only anti-smoking agent varenicline triple their likelihood of successfully kicking the habit, compared with trying to quit without medication, a new review concludes.

Pfizer's varenicline was approved in 2006 by the US FDA under the trade name Chantix and by European regulators under the trade name Champix.

The drug partially stimulates nicotine receptors in the brain, which helps reduce nicotine withdrawal symptoms. It also partially blocks nicotine from attaching to these receptors, making smoking less satisfying and so curbing a person's desire to smoke.

Dr. Kate Cahill, from Oxford University, UK and colleagues analyzed data from six Pfizer-sponsored studies that compared the effects of varenicline with placebo. Three of these also included a comparison with bupropion, an antidepressant that is also used for smoking cessation. The six trials included 4,924 smokers, 2,451 of whom used varenicline.

The results are reported in the latest issue of The Cochrane Library, a publication of The Cochrane Collaboration, an international organization that evaluates medical research.

In the pooled analysis, Cahill and her colleagues found that people who took a varenicline pill twice daily increased their odds of being continuously cigarette-free at one year approximately three-fold compared with people assigned a placebo. Success rates were also 1.6-times greater with varenicline than bupropion.

The jury remains out on the value of varenicline in helping ex-smokers from taking up smoking again.

The main side effect of varenicline is mild to moderate nausea, which subsides with time, the researchers say.

"Additional and independent randomized trials of varenicline are needed to confirm the early findings from industry trials," Cahill's team concludes. "There is also a need for direct comparisons with nicotine replacement therapy; and for further trials with bupropion, to establish the relative efficacy of the treatments."

Read Full Story