Restrictions on Pfizer's Chantix as reports of neuropsych AEs prompt fresh concerns

New safety concerns on Pfizer's Chantix (varenicline) could slow the sales expansion of the smoking-cessation drug and land the world drug giant into legal difficulties, observers suggest.

Chantix is facing greater scrutiny after a US non-profit organization published a report stating its concern about the use of varenicline in settings where the risk of accident is high and recommended that doctors and patients consider alternative methods of smoking cessation.

The study from the Institute for Safe Medication Practices found that, in fourth-quarter 2007, varenicline accounted for 988 serious injuries in the USA reported to the Food and Drug Administration, more than any other individual drug in this time period. By comparison, the FDA received a median of five reports of serious injury for 769 different drugs during the period. Only 35 drugs accounted for 100 or more reports. This large volume of adverse events prompted the Institute to conduct an analysis of all AEs for varenicline since it was approved in 2006.