The smoking cessation drug Chantix (varenicline) can amplify the effects of alcohol, and the two should be combined with caution, according to a drug safety communication released by the Food and Drug Administration (FDA) on Monday, March 9.
In addition, the FDA warns that Chantix may in rare cases cause seizures and changes in mood, behavior, and thinking.
People taking Chantix have reported a lower tolerance to alcohol while on the medication, resulting in getting more drunk, aggressive behavior, and an inability to remember events that occurred while drinking (amnesia). Reports were gathered via the FDA’s Adverse Event Reporting System (FAERS) and directly from Pfizer, the maker of Chantix.
There have been 11 reports to FAERS of decreased tolerance to alcohol and 37 reports of aggressive behavior when alcohol and Chantix were combined since Chantix was FDA approved in 2006.
The FDA recommends that “until patients know how Chantix affects their ability to tolerate alcohol, they should decrease the amount of alcohol they drink.”
The agency also reports a small risk of seizures from Chantix in people who have no history of seizure disorder or have a seizure disorder that has been well-controlled. These seizures are most likely to occur within the first month of starting Chantix. There have been 64 reported cases of seizures among people on Chantix since 2006; of those, 37 had no history of seizure.
According to FDA data, 1.3 million people are prescribed Chantix each year.
FDA Continues to Examine Neuropsych Effects of Chantix
The FDA has already twice reported on neuropsychiatric and behavioral effects of Chantix—first in 2009 and then again in 2011. This time, they include data on a number of observational studies and on a meta-analysis conducted by Pfizer of five randomized, controlled, clinical trials.
The results of the analysis by the drug’s maker “showed no increase in the incidence of suicidal ideation and/or behavior in patients treated with Chantix compared to patients treated with placebo,” according to the FDA.
However, some of those studies included people who already had severe mental illnesses, including schizophrenia, schizo-affective disorder, and depression—which carry a higher risk of suicidal ideation and behavior anyway. So it might be difficult to tease out if suicidal thoughts are the result of the pre-existing mental disorder or of Chantix.
Pfizer is currently conducting a large clinical safety trial on Chantix; results should be available later this year.
The four observational studies examined by the FDA included more than 40,000 patients taking Chantix. These looked at neuropsychiatric hospitalizations and fatal and nonfatal self-harm in people taking Chantix compared to those taking nicotine replacement therapy (such as a patch or gum) or bupropion (Wellbutrin).
These studies had limitations of their own. For example, the FDA notes, bupropion may carry its own risks of neuropsychiatric effects, so comparing it to Chantix is not necessarily a good way to measure these risks. (In other words, just because Chantix doesn’t cause more suicidal ideation than Wellbutrin does not mean that Chantix doesn’t cause suicidal ideation.)
Finally, the combined analysis of all these studies doesn’t examine the full list of neuropsychiatric effects from Chantix that have been reported to FAERs over the years, which include agitation, hostility, aggressive behavior, depression, suicidal thoughts or actions, or other changes in behavior.
Ultimately, the FDA concluded, “Although the findings of the observational studies appear reassuring, they do not completely evaluate the effect of Chantix on neuropsychiatric adverse events and cannot be interpreted to mean that there is no risk of neuropsychiatric events with Chantix. The limitations in these studies may underestimate the actual incidence of neuropsychiatric adverse events and restrict our ability to predict the direction of the relative risk associated with Chantix.”
The full safety announcement can be found on the FDA website
Photo courtesy of Paul Aloe on flickr