Pfizer's Chantix Woes Bash High Hopes

"We will be partnering with physicians and corporate hospital chains to set up 600 specialized smoking-cessation clinics called 'Champix Clinics,'" Kewel Handa, the chief of Pfizer's India operations, told Delhi-based Mint in March. But "we are informing the physicians to recognize the risks ... We will also be doing a vigorous post-marketing study, involving 500 people in the country."

Since India is home to more than 200 million smokers, that might look like a small sample to some. Like many foreign countries, however, India features a much weaker regulatory system than America's own.

Lately, Pfizer has started to focus a lot more on those international markets. Last quarter, in fact, the company generated more revenue outside the country than it did at home. While international demand for Chantix continued to build, domestic sales of the drug actually slipped a bit on a sequential basis.

Here at home, the situation has apparently worsened. Last month, Anderson estimated that U.S. doctors were writing almost 30% fewer prescriptions for Chantix than they were a year ago. If U.S. regulators order a dreaded "black box" warning for Chantix -- a possibility Anderson has actually raised -- that number could plunge even more.

"The worst-case outcome is that the FDA withdraws the product from the market," Anderson wrote. But, he added, "this is not what we currently model."

Still, he wrote, "while Chantix has better efficacy than existing smoking cessation agents ... it is possible that the FDA determines at a later date that the safety issues with Chantix outweigh the benefits" in the end.