US FDA orders "black box" suicidality warnings and studies for Chantix and Zyban

The US FDA has ordered Pfizer and GlaxoSmithKline to add "black box" label warnings about serious neuropsychiatric effects for the smoking cessation drugs Chantix (varenicline) and Zyban (bupropion). The companies also must conduct postmarketing clinical trials to determine the incidence of serious neuropsychiatric symptoms, including depression and suicidality, in patients taking the therapies.

Although the agency's action with regard to Chantix was not unexpected, the decision to extend the warnings and postmarketing study requirement to Zyban was surprising and prompted by adverse event...