On May 16, 2008, the United States Food and Drug Administration (FDA) issued a public health advisory concerning Pfizer’s smoking cessation drug Chantix. Pfizer has, at the request of the FDA, added warnings about the possibility of severe changes in mood and behavior in Chantix patients.

In November of 2007, the FDA first notified the public about the possibility of severe changes in mood and behavior in Chantix patients, but at that time, the connection between Chantix and the symptoms was unclear. However, as the FDA continued to review the data, the agency determined it was increasingly likely that these severe behavioral changes may be related to Chantix.

It is estimated that 44 percent of all cigarettes in the United States are smoked by people with diagnosed mental disorders, including schizophrenics and alcoholics. Smokers with psychiatric illnesses were not included in Pfizer’s premarketing trials for Chantix, however, leading to one possible explanation for the flood of adverse event reports. Chantix is marketed and sold to all adult smokers, regardless of mental health status.

In early February of this year, the FDA reported receipt of 420 reports of suicidal thoughts and 34 suicides among the 4.5 million Americans using Chantix.

As a result, the FDA has provided the following safety information on Chantix:

• Patients who are taking Chantix should tell their doctor about any history of psychiatric illness before they begin to take Chantix because the drug may cause worsening of a psychiatric illness or may cause an old psychiatric illness to reoccur.
• Patients treated with Chantix should be monitored for changes in mood and behavior, including anxiety, nervousness, tension, depression, unusual behaviors and suicidality. Patients who stop taking Chantix should also be monitored for these symptoms.
• A patient who experiences changes in mood and behavior while taking Chantix should immediately report the changes to the doctor.
• Chantix patients may experience vivid, unusual or strange dreams.
• Impairment of the ability to drive or operate heavy machinery may occur in Chantix patients.

Both the FDA and Pfizer are working to finalize a Medication Guide for Chantix patients. The FDA will notify the public about any new information arising from its review of Chantix data. The agency may also consider additional changes to Chantix prescribing information.

Source: “Public Health Advisory: Important Information on Chantix (varenicline),” United States Food and Drug Administration Public Health Advisory, May 16, 2008; Melinda Beck, “Puff Power: Drug Warnings Speak to Nicotine’s Sad Grip,” Wall Street Journal, February 19, 2008.