Label to warn of aggressive alcohol interaction for Pfizer’s Chantix

The prescription medicine for stopping smoking can change the way people react to alcohol, and has been associated with aggressive behaviour and rare accounts of seizure, according to the US Food and Drug Administration (FDA).

“Until patients know how Chantix affects their ability to tolerate alcohol, they should decrease the amount of alcohol they drink. Patients who have a seizure while taking Chantix should stop the medicine and seek medical attention immediately,​” said the Agency.

Data submitted by Pfizer and from the FDA Adverse Event Reporting System (FAERS) database showed some patients who drank alcohol while taking Chantix experienced decreased tolerance to alcohol, including getting more drunk, behaving unusually or aggressively, and having memory loss.

The FDA also ordered changes to the Warnings and Precautions section of Chantix’s label to include information about studies into the neuropsychiatric effects of the drug on mood, behaviour and thinking.

Observational studies and clinical trial data “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,” said the FDA.

Pfizer is conducting a large clinical safety trial of Chantix to investigate behavioural risks. Results are expected later this year.

History of side effects​

The FDA has warned the public about possible serious neuropsychiatric side effects of Chantix in the past.

In 2009 it required Pfizer to place a boxed warning notifying users the medicine was associated with behavioural changes such as hostility, agitation, depressed mood, and suicidal thoughts or actions.

Two FDA-sponsored epidemiological studies concluded in 2011 there was no difference in rates of psychiatric hospitalisation between Chantix and nicotine replacement therapies, “however, both studies had a number of study design limitations,​” including only assessing hospitalisation as a marker of mental health outcomes and not having a large enough sample size to detect rare adverse events, said the Agency.

“Although these two studies did not suggest an increased risk of neuropsychiatric events that result in hospitalization, they do not rule out an increased risk of other neuropsychiatric events with Chantix.​”

Studies show Chantix increases the likelihood that patients will continue to abstain from smoking for as long as one year compared to a placebo. The drug works by blocking the effects of nicotine on the brain, and unlike many other smoking cessation therapies does not itself contain nicotine.