Last week, the Food and Drug Administration gave Pfizer, Inc. approval to market varenicline (trade name, Chantix), a new drug aimed at helping individuals stop smoking.
Varenicline is classified as a nicotine-receptor blocker. The drug binds to the receptors for nicotine within the brain, thus preventing nicotine itself from binding to those receptors. As a result, the drug reduces or eliminates the pleasurable effects people experience from smoking. At the same time, the drug has a mild stimulating effect on those same nicotine receptors - an effect that helps reduce nicotine withdrawal symptoms.
Recent studies conducted by Pfizer suggest that smokers are more likely to successfully quit cigarettes with varenicline than with either a placebo or bupropion (Zyban, another anti-smoking drug). While the success rate was significantly improved with varenicline, the drug is no panacea. Only about 50% of individuals receiving varenicline successfully stayed off cigarettes for the full 12-week course of therapy, and only about 25% of those treated stayed off for as long as 1 year.
The FDA approval of varenicline allows for a treatment course of 12 weeks, though a second 12-week course can be given in some individuals. The most common known side effects appear to be related to gastrointestinal symptoms (of nearly every description), headache, and sleep disturbances.