CBS/AP) Does Chantix make people crazy? Two new studies failed to turn up a link between the antismoking drug and psychiatric problems like depression and suicidal thoughts, government health officials said, but the findings are not definitive.
The FDA has been looking into reports of mood disorders and erratic behavior among Chantix users since 2007. The agency said in a statement that two federally funded studies involving more than 26,000 people did not show an heightened rate of psychiatric hospitalizations among Chantix patients, compared with those using nicotine patches and smoking cessation treatments.
FDA officials stressed that the studies looked only at psychiatric problems that resulted in hospitalization, meaning many issues may have gone unreported. In addition, the studies by the Department of Veterans Affairs and the Department of Defense weren't large enough to pick up rare side effects.
Groups like the Federal Aviation Administration have already banned the drug for pilots and air traffic controllers because of side effects that could interfere with their work.
The FDA said it was continuing to study the problems and urged patients to consult their doctors if they experience side effects with the drug. The drug's maker, Pfizer, is conducting its own large-scale study of Chantix's behavioral effects, but the results won't be available until 2017.
"Healthcare professionals should advise patients and caregivers that the patient should immediately stop taking Chantix and contact a healthcare professional if agitation, hostility, depressed mood, or changes in behavior or thinking that are not typical for the patient are observed," the FDA said in an online statement.
Chantix works by binding to the same spots in the brain that nicotine does when people smoke, blocking nicotine from those spots but causing release of a "feel-good" chemical, dopamine. The drug's label carries a boxed warning, the most serious type, listing possible side effects including hostility, agitation, depression and suicidal thoughts and behavior.
More than 8.9 million people in the U.S. have filled prescriptions for Chantix since it was approved in May 2006.
The CDC has more on smoking cessation.