What happens when violence is a side effect of a medication? Most people don't believe that a drug could alter behavior, but that is exactly what a new study concludes (PLoS ONE, December 2010).
The investigators analyzed reports submitted to the Food and Drug Administration's Adverse Event Reporting System from 2004 through September 2009. They found that a relative handful of drugs (about 30 out of nearly 500) were associated with reports of homicide, thoughts of homicide, physical assault, physical abuse or other aggression toward others.
The stop-smoking drug varenicline (Chantix) led the list. The scientists noted that "Varenicline had the strongest association with violence by every measure used in this study."
Readers of this column also have reported violent reactions in people taking Chantix. The first report to our website (January 2008) linked this behavior to alcohol combined with Chantix: "I live in the U.K. On Christmas Eve, my boyfriend had been using Chantix for some months. He was drinking and went berserk for no reason, assaulted me and destroyed my apartment. As far as I know he has no past mental-health problems or history of violence."
Another reader offered a surprisingly similar report: "My brother took Chantix for about a month, went berserk, beat his wife with no provocation and then called the police. He has no recollection of the incident and had visual hallucinations before this bizarre and tragic episode. His wife of 19 years divorced him, he's now homeless, and he's facing multiple felony charges."
Although Chantix does help many people stop smoking, those who take it should be alerted to the official warning in the prescribing information: " the patient should stop taking Chantix and contact a healthcare provider immediately if agitation, hostility, depressed mood, or changes in behavior or thinking that are not typical for the patient are observed " There also is mention of "psychosis, hallucinations, paranoia, delusions, homicidal ideation, aggression, hostility, anxiety, and panic, as well as suicidal ideation, suicide attempt, and completed suicide."
Chantix is not the only drug linked to suicidal thoughts or aggressive behavior. After years of controversy, the FDA required manufacturers of many antidepressants to include a special black-box warning about the potential for such drugs to trigger suicidal thinking or behavior.
The new study identified 11 of these drugs as also associated with violent acts toward others. A reader of this column reported her experience on fluoxetine (Prozac): "After a month, wild thoughts came into my mind, especially while driving. I wanted to ram into other cars to show them they shouldn't drive so rudely. I wanted to get a gun and kill a co-worker who irritated me."
Americans have a hard time accepting the idea that a drug could drive someone to aggression. Personal responsibility is a strong value in our culture. To live up to it, though, people need to be informed when violence could be a side effect of their medication.