Chantix Side Effects Linked to More Violence Than Any Other Drug: Study

According to a new study, side effects of Chantix have been linked to hundreds of acts of violence in the United States in recent years, many of them suicides or attempted suicides, putting Pfizer’s smoking cessation drug at the top of the list of prescription drugs associated with violent acts.

In a report published last week in the medical journal PLoS ONE, researchers from the Institute for Safe Medication Practices, Cambridge Hospital and Wake Forest University looked at FDA adverse event reports over a period of five years, up to 2009.

Chantix was linked to 408 reported cases of violence, more than double the number of instances reported for any other drug on the market in the U.S. The drug with the second highest number of violent incidents reported, Paxil, had only 177.

In addition to being the drug associated with the most reported incidents of violence, researchers said that Chantix was also associated with the highest rate of violent acts in proportion to the number of users.

The findings, which accounted for violent acts that may be associated with the psychological effects of quitting smoking, comes as a growing number of people have filed a Chantix lawsuit against Pfizer, alleging that the drug maker failed to warn consumers about the risk of psychological Chantix side effects.

Chantix (varenicline) was approved in the United States by the FDA in 2006 as a prescription medication to help people quit smoking. The drug works by reducing the positive feelings that come from cigarettes, blocking the receptors in the brain commonly stimulated by nicotine. However, the impact of the drug on the brain has resulted in a number of reports from users who experienced sudden, unusually aggressive behavior, thoughts of self-harm and suicide.

Researchers said that the common link between Chantix, Paxil and other drugs associated with acts of violence appears to be an increased release of dopamine or seratonin to the brain. The researchers also noted that Chantix was peculiar in that the urge to commit senseless acts of violence appeared rather quickly after patients began taking Chantix and that the side effects disappeared rapidly after use of Chantix was discontinued.

The same group of researchers released a report in July detailing the risk of violent and aggressive behavior on Chantix, which found that people affected by the drug had the tendency to lash out at anyone nearby, including loved ones and family members.

In that study, the researchers found that the acts of violence were inexplicable and unprovoked, the Chantix users victimized anyone nearby, there was no prior indication of similar behavior and the psychiatric side effects occurred quickly; often before they had gotten to the point in their Chantix use where they had stopped smoking. Researchers found that violent and aggressive behavior ended for 93% of the subjects when they stopped taking Chantix.

In June 2009, a “black box” warning was added to the medication about the potential risk of problems with Chantix, indicating that some users have experienced changes in behavior, depression and suicidal thoughts. Pfizer has also been required to conduct clinical trials providing more data on how often neuropsychiatric symptoms and suicide with Chantix occur and what conditions cause them.

Lawsuits over Chantix have been filed in state and federal courts throughout the United States on behalf of individuals who have suffered injuries from the neuropsychiatric side effects of Chantix, as well as for family members of individuals who have committed suicide on Chantix.

In October 2009, the U.S. Judicial Panel on Multidistrict Litigation consolidated the federal Chantix litigation in the U.S. District Court for the Northern District of Alabama. According to a pretrial scheduling order issued earlier this year, the first Chantix trial is unlikely to reach a jury until at least 2012.