Nov. 3, 2011 -- Just over a week after federal health officials released a report finding no evidence of an increased risk of serious psychiatric problems in users of the anti-smoking drug Chantix, a new study comes to the opposite conclusion.
Investigators who were the first to link the drug to suicidal behavior and depression say the new research suggests that Chantix may be too risky to use as a first treatment for smoking cessation and should only be used when other treatments have failed.
Representatives of FDA and Pfizer, the drug's manufacturer, strongly disagree with the new study findings.
The researchers found that 90% of all reported suicides related to anti-smoking treatments from 1998 to 2010 involved Chantix, even though the drug has only been on the market in the U.S. for about four years.
"We believe this drug is not suitable for use as a first choice for people who are trying to stop smoking," study researcher Thomas J. Moore tells WebMD. Moore is a senior scientist with Safe Medicine Practices, an independent drug safety research group.
The researchers say that use of Chantix was eight times more likely to result in suicidal behavior or depression than use of nicotine-replacement gums, patches, lozenges, and inhalers.
They are asking the FDA to revise its labeling for Chantix to show this increased risk. But an FDA official is calling the researchers' conclusions misleading.
The new study was published online this week and appears in the November issue of PLoS One.
Conflicting Studies on Chantix
The FDA is standing by its Oct. 24 review of two FDA-sponsored studies that examined hospitalizations for psychiatric reasons in users of Chantix and nicotine-replacement therapy. But the FDA also acknowledges that the studies had significant limitations that made it impossible to rule out an increased risk of suicidal behavior and depression associated with the drug.
The studies found no evidence of an increase in hospitalizations for psychiatric reasons in Chantix users compared to nicotine patch users.
In the new analysis, Moore and colleagues from Wake Forest University, Harvard Medical School, and Johns Hopkins University School of Medicine analyzed 3,249 cases of depression and self-injury in Chantix users from 1998 to 2010, as well as users of the antidepressantZyban, which is approved for smoking cessation, and other nicotine-replacement treatments.
The cases were reported to the FDA's Adverse Event Reporting System.
A total of 2,925 of the reported cases involved Chantix (90%), 229 occurred in Zyban users (7%), and 95 (3%) occurred in users of tobacco-replacement treatments.
In an email, FDA spokeswoman Karen Riley said much of the data used by Moore and colleagues in the new report were not new and had led to the "black box" warning that appears on the drug's labeling. A black box warning is the FDA's most serious warning.