The US Food and Drug Administration announced yesterday it is requiring a black box warning for two drugs used to aid smoking cessation, Chantix (varenicline, Pfizer, New York) and Zyban (bupropion, GlaxoSmithKline, London). The revised labeling information will explain the risks associated with taking the mediciations, specifically, the “serious mental health events including changes in behavior, depressed mood, hostility, and suicidal thoughts” according to an FDA press release. FDA says its request is based on analysis of information from its Adverse Event Reporting System as well as clinical trial data and scientific literature.

Janet Woodcock, director of the FDA’s Center for Drug Evaluation and Research, recommended that doctors watch patients for mood or behavioral changes after taking these drugs, and also advised patients experiencing these symptoms to immediately contact their physicians, according to the press release. She did not recommend people stop using the products, saying the drugs can be effective in helping people quit smoking. “The risk of serious adverse events while taking these products must be weighed against the significant health benefits of quitting smoking,” she said.

Pfizer released a statement yesterday announcing it has updated the labeling for Chantix. Briggs W. Morrison, senior vice president of the Primary Care Development Group at Pfizer, said, “The labeling update underscores the important role of health care providers in treating smokers attempting to quit and provides specific information about Chantix and instructions that physicians and patients should follow closely. Quitting smoking is one of the best things people can do for their health, but the quitting process is both difficult and complex.” Chantix was approved in May 2006, and its labeling has included certain information about psychiatric effects since November 2007, according to the press release.

Zyban, which was approved as a smoking-cessation aid in 1997, is also marketed as the antidepressant Wellbutrin, which already carries typical antidepressant warnings about suicide risks.