The Food and Drug Administration (FDA) issued a safety announcement on Monday warning that Pfizer Inc.’s smoking-cessation drug, Chantix (varenicline), has been associated with seizures. Some patients who drink alcohol while taking the drug may become aggressive or black out.
In September, the FDA approved an update to the drug’s label but issued the public notice to ensure patients are aware of the changes “and can consider this new information when making prescribing decisions,” Reuters reports.
Chantix received FDA approval in 2006 for use in helping adults quit smoking. The FDA subsequently updated the label to include a warning – in a black box – to warn of neuropsychiatric side effects, including suicidal thoughts, hostility and agitation. Boxed warnings are used for the most serious risks. Pfizer asked the FDA to remove the black box, saying its own studies show no association between Chantix and severe psychiatric side effects, Reuters reports. In October an FDA advisory committee recommended keeping the black box pending the outcome of an ongoing safety study.
The FDA identified cases in which the patients who had seizures while taking Chantix either had no history of seizures or had a seizure disorder that had been well controlled. In most of these cases, the seizures occurred within the first month of starting Chantix, according to the safety announcement.
The FDA examined a variety of studies, including those conducted by Pfizer. “These studies did not show an increased risk of neuropsychiatric side effects with Chantix; however, they did not examine all types of neuropsychiatric side effects, and they had limitations that prevented us from drawing reliable conclusions,” the agency said.
Pfizer is conducting an additional safety study of the drug, which generated $647 million in revenue in 2014, according to Reuters. Results of the trial are expected late this year. The black box warning will remain at least until the results of the trial are announced.