The FDA says Pfizer's study of neuropsychiatric effects of its smoking cessation drug Chantix may have presented confusing data on adverse events, potentially biasing the research.
Since approval in 2006, varenicline has been linked to serious neuropsychiatric events, including suicidal thoughts and behavior. The FDA placed a black box warning on the product in 2009, highlighting this risk.
The most recent varenicline clinical trial also included GSK's Zyban. The FDA is using the trial data to decide whether Pfizer can cut the boxed warning on Chantix regarding potential changes in behavior, depressed mood and suicidal thoughts. However, FDA staff has raised questions about a lack of consistency in how the company study recorded neuropsychiatric events.
Among the problems cited by the FDA, according to STAT: trial investigators did not always make appropriate use of a side effect index; investigators inconsistently assessed the severity of side effects; there was inconsistent handling of cases involving suicidal behaviors; and a lack of information about the circumstances surrounding side effects.
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