FDA Finds More Issues With Pfizer’s Quit-Smoking Drug Chantix

The FDA is warning that Pfizer’s Chantix smoking-cessation aid may cause seizures or, when taken with alcohol, lead to unusual or aggressive behavior.

The agency requested these risks be added to the Warnings and Precautions section of Chantix’s (varenicline) label and Medication Guide after both Pfizer’s and the FDA’s adverse event reports found that the few patients who had seizures either had no history of them or had a previously well-controlled seizure disorder.

The new risks come atop earlier concerns of hostility, agitation, depression and suicidal thoughts or actions that led the FDA in 2009 to require a boxed warning on Chantix’s label.

Pfizer has pressed the FDA to remove the boxed warning, citing five placebo-controlled trials that found no increase in suicidal thoughts or suicide attempts, as well as a pooled analysis of 18 trials that showed only a small risk of anxiety, depression or other mood disorders in patients taking Chantix.

In a safety communication, the FDA says the studies did not evaluate a wide enough range of behaviors and had limitations that prevented regulators from drawing solid conclusions. Nonetheless, the agency updated the Warnings and Precautions section of the drug’s label to reflect the studies.

Pfizer spokesman Steve Danehy expressed surprise at the announcement, saying the drugmaker made these labeling changes in September. The company is conducting a large safety trial in the hopes of getting the boxed warning removed, with results expected later this year. — Lena Freund