Concerns over bias raised as FDA documents doubt Pfizer's data on Chantix

Documents on the smoking cessation product Chantix (varenicline) which will be considered by a US Food and Drug Administration (FDA) advisory committee on Wednesday have questioned the validity of data provided by Pfizer (NYSE: PFE).

The committee will meet to discuss a post-marketing study of the US pharma giant’s product, which is marketed as Champix outside the USA and, along with UK pharma major GlaxoSmithKline's (LSE: GSK) smoking cessation treatment Zyban (bupropion), carries a boxed warning regarding the risk of serious neuropsychiatric events following adverse reports of such cases.

In 2008, the FDA imposed a post-marketing requirement (PMR) which demanded that Pfizer and GSK conduct a placebo-controlled post-marketing safety trial to further characterize the risk of neuropsychiatric adverse events.