FDA warns of anti-smoking drug Chantix' suicide risk

The world’s leading pharmaceutical company, Pfizer Inc's smoking-cessation drug Chantix induces many behavioral changes in a person, the Food and Drug Administration warned on Friday. The most common of these side effects are suicidal thoughts, aggressive and violent behavior, vivid nightmares and erratic mood swings, the agency said.

The health regulators issued the warning after analyzing the cases of depression, suicidal thoughts and other unusual behavior in patients using the drug. They found the stronger evidence of an association between erratic behavior and serious mood symptoms and Chantix.

"We've become increasingly concerned as we've seen there are a number of compelling cases that truly look as if they are the result of exposure to the drug and not to other causes," Bob Rappaport, a director in FDA's unit that oversees Chantix, told reporters on a conference call.

"These cases involve abnormal behaviors, changes in mood, and suicidal ideation and suicide," Rappaport added.

FDA’s warning comes days after Pfizer said it has added stronger warnings to its popular anti-smoking drug Chantix, including language about depression and suicidal behavior.

On Jan, 18, Pfizer said it has updated the Chantix label, prominently warning that patients who are attempting to quit smoking by taking drug should be observed by a physician for serious neuropsychiatric symptoms like changes in behavior, agitation, depressed mood, suicidal ideation and suicidal behavior.

Pfizer at the time stressed on the fact that a direct link between Chantix and the problems has not yet been established, but it also cannot be ruled out.

The US health watchdog has received 491 reports of suicidal behavior associated with Chantix, said Dr. Celia Winchell, a team leader in the FDA's Division of Anesthesia, Analgesia and Rheumatology Products. Of the total reported cases, 420 are from the United States. And, of the total 39 completed suicide cases, 34 are alone in the United States.

Chantix is a nicotine-free, oral tablet which is to be taken twice a day for 12 weeks to help adults quit smoking. This works by cutting the pleasure of smoking and reducing withdrawal symptoms by the help of an active ingredient Varenicline.

Chantix was approved in May 2006 and has since been prescribed more than 4.0 million times in the U.S. alone. The drug has been a success story for Pfizer having generated sales of $280 million in the fourth quarter of 2007 compared to older drugs which face stiff competition from cheaper generics.