An article and accompanying editorial in the December 1, 2013 issue of the American Journal of Psychiatry offer strong support for the safety of varenicline (Chantix), which appears to be the most effective drug available as an aid in smoking cessation. First reviewed in The Medical Letter in 2006, varenicline was the second non-nicotine drug to gain FDA approval for treatment of tobacco dependence. Soon after its approval, as happens with many new drugs, the FDA began to receive reports of adverse events. In this case, the agency incorporated some of those reports into warnings in the Chantix package insert, stating that serious symptoms, including agitation, changes in behavior, depressed mood, suicidal ideation, and suicidal behavior had occurred in patients who took varenicline.
In a review of drugs for tobacco dependence, published in the September 2008 issue of Treatment Guidelines from The Medical Letter, we pointed out that smoking itself has been associated with psychiatric disease and that psychiatric symptoms including suicidal ideation and completed suicide have been associated with both smoking and smoking cessation.
The recent article in the American Journal of Psychiatry by Robert D. Gibbons and J. John Mann, was an analysis of 17 randomized controlled trials conducted by the manufacturer (Pfizer) in a total of more than 8000 patients and data on rates of neuropsychiatric adverse events compiled by the Department of Defense from more than 35,000 patients receiving varenicline or nicotine replacement therapy. In the randomized controlled trials, varenicline increased the risk of nausea (a known adverse effect of the drug), but not of aggression, agitation, depression, or suicidal events. In the Defense Department study, the rate of neuropsychiatric disorders was significantly lower with varenicline than with nicotine replacement products.
The accompanying editorial, by A. Eden Evins, points out that adverse event reports like these put us (investigators, editors and, most importantly, prescribers) in the difficult position of trying to prove the absence of an association between a useful drug and adverse events known to occur in the condition the drug is treating. There is no easy answer to this problem, and it is certainly not limited to varenicline and smoking.