Contrary to FDA warnings on the matter, a UK study has found “no clear evidence” to support the claim that the cigarette cessation drug Chantix increases the risk of suicidal thoughts and suicide.
To reach these conclusions, David Gunnell and colleagues at the University of Bristol reviewed the records of 80,660 men and women aged 18-95 years that had received a smoking cessation product (Chantix, Zyban or nicotine replacement therapy) between September 2006 and May 2008.
The scientists found 166 episodes of nonfatal self-harm and 2 suicides — both occurring in patients receiving nicotine replacement therapy. An additional 37 subjects reported having suicidal thoughts.
Chantix and Zyban did increase the risk of such phenomena by 12% and 17% compared with nicotine replacement products in the study, but this difference did not achieve statistical significance. The authors were left to conclude there was no clear evidence that Chantix was associated with an increased risk.
The limited study power “means we cannot rule out either a halving or a twofold increase in risk,” according to the authors.
Chantix also did not appear to increase the risk of depression or suicidal thoughts, confirming a report last March.
The FDA issued black box warnings for both Chantix and Zyban last July, and regulatory agencies around the world followed suit after adverse event reports raised the possibility of such a relationship.
The authors noted that smokers have a nearly threefold increased risk of suicide, probably because people with psychiatric illnesses are far more likely to be smokers.
It’s possible, they said, that smoking “has a beneficial effect on psychiatric symptoms, such as anxiety, that may be lost with smoking cessation.”
The write-up is in the British Medical Journal.