FDA Unconvinced on Suicide Risk of Smoking Cessation Pills

FDA staff are not convinced that the smoking-cessation drugs varenicline (Chantix), developed by Pfizer, and bupropion (Zyban), developed by GSK, do not increase suicidal tendencies among users.

An international double-blind study, conducted in more than 8000 participants across 16 countries over a 3-year period, showed that the drugs did not increase the risk of suicide in users with a history of psychiatric disorders. The results of this study were published earlier this year in Lancet.

The study found that among participants without psychiatric problems, the risk of suicidal thoughts or behavior or other serious mental health issues was very low and statistically the same: about 1.3% for those taking Chantix, 2.2% with Zyban, 2.5% with the nicotine patch, and 2.4% with a dummy pill. Among those with psychiatric problems, the risks were higher across the board: about 6.5% for Chantix and Zyban and 5% for the nicotine patch and dummy pill.

Following those results, Pfizer was ardently pursuing the removal of a black box warning from the drug’s label, which warns of psychiatric risks including suicidal thoughts, hostility, and agitation among it’s users.

However, according to Reuters, the FDA has doubts about the data collection methods and characterization of the severity of some of its side effects—factors than can lead to biased results, the FDA said. External advisers to the FDA are scheduled to meet to discuss the results of the study and recommend whether the black-box warning can come off of the drug label. The FDA can consider the advice but may not act on it.

“Ultimately, what was reported as an adverse event, was determined based upon the investigator's local determination of the subject presenting in front of them,” James Rusnak, MD, PhD, chief development officer of Pfizer’s cardiovascular metabolic unit, told Reuters.

Chantix was approved in 2006 and has patent exclusivity till 2020. Despite the controversy surrounding the drug, Pfizer earned $671 million from global sales of the drug in 2015.