US government regulators have said a connection between Pfizer’s anti-smoking drug Chantix and serious psychiatric problems is “increasingly likely”.
The Food and Drug Administration (FDA) said it has received reports of 37 suicides and more than 400 of suicidal behaviour in connection with the drug.
Back in November, the agency began investigating reports of depression, agitation and suicidal behaviour among patients taking the twice-daily treatment.
And two weeks ago, Pfizer added stronger warnings to Chantix. In doing so, the company stressed that a direct link between the drug and the reported psychiatric problems has not been established, but could not be ruled out.
The pharmaceutical firm suggested that since nicotine withdrawal alone can cause mood swings and agitation, it may be impossible to determine if Chantix aggravates those behaviours.
But the FDA has said that it has now found evidence of Chantix patients who experienced psychiatric problems even though they were still smoking.
Bob Rappaport, a director at the FDA’s drug evaluation centre, said: “There are a number of compelling cases that look like they are the result of exposure to the drug itself and not other causes.”
In a public advisory, FDA said patients taking Chantix should tell their doctor about any history of mental illness, and that patients and family members should watch for any changes in mood and behaviour.
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