The US Food and Drug Administration (FDA) is requiring manufacturers of the smoking cessation drugs Chantix (varenicline) and [removed]Zyban[/removed] (bupropion) to put a Boxed Warning on the prescribing information. The warning highlights the risk of serious mental health events when taking these drugs, including changes in behavior, depressed mood, hostility, and suicidal thoughts.

“The risk of serious adverse events while taking these products must be weighed against the significant health benefits of quitting smoking,” said Janet Woodcock, MD, director of the FDA’s Center for Drug Evaluation and Research in an announcement about the label changes.

According to Woodcock, health care professionals who prescribe Chantix and Zyban should monitor their patients for any unusual changes in mood or behavior after starting these drugs. She added that patients who experience such changes should immediately contact their health care professional.

The FDA’s request for the additional warnings is based on an analysis of information from clinical trials and scientific literature and a review of reports submitted to the agency’s Adverse Event Reporting System since the time the products were marketed.

The review found that some patients who have taken Chantix and Zyban reported experiencing unusual changes in behavior, becoming depressed or having their depression worsen, and having having thoughts of suicide or dying. According to the FDA, in many cases, the problems began shortly after starting the medication and ended when the medication was stopped. However, the FDA did report that some people continued to have symptoms after stopping the medication; while, in a few cases, the problems began after the medication was stopped.

Neither Chantix nor Zyban contain nicotine and some of these symptoms may be a response to nicotine withdrawal, said the FDA in the announcement about the labels. However, some patients who were using these products experienced the reported adverse events while they were still smoking.

The FDA is also requesting more information in the Warnings section of the prescribing information and updated information in the Medication Guide for patients that further discuss the risk of mental health events when using these products.

Manufacturers will be required to conduct a clinical trial to determine how often serious neuropsychiatric symptoms occur in patients using various smoking cessation therapies, including patients who currently have psychiatric disorders.