The Food and Drug Administration says it will keep a bold-letter warning on Pfizer's anti-smoking drug Chantix about suicidal behavior and other psychiatric problems.
Pfizer Inc. asked the agency last year to drop the so-called black box warning, pointing to its own analyses that found no difference in psychiatric problems between people taking Chantix and other stop-smoking treatments.
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But the FDA said in an online posting Monday that Pfizer's data did not examine all types of psychiatric problems and had limitations preventing regulators "from drawing reliable conclusions."
The agency's decision follows the recommendation of a panel of outside experts, who voted last October to keep the warning on the drug. New York-based Pfizer is expected to complete a larger study of Chantix's psychiatric side effects in late 2015.