FDA votes to keep black box warning on Pfizer anti-smoking drug

Majority of the panel votes to keep the most severe warning label on the treatment

Pfizer Inc failed in its attempt to remove a black box warning from its controversial quit-smoking drug, Chantix, after an advisory panel to the US Food and Drug Administration voted against the removal.

A majority of the panel voted to keep the health regulator's most severe warning label on the treatment, in keeping with the recommendations of FDA staff two days earlier.

Chantix, also known as varenicline, is one of Pfizer's most controversial drugs and has a number of severe side effects, including suicidal thoughts, erratic behavior and drowsiness.

The FDA had placed a black box warning - its most severe and restrictive warning - on the product in 2009, highlighting the drug's adverse neuropsychological effects.