November 6, 2004Bextra, a Pfizer pain drug that received a sales boost when Merck's Vioxx was pulled from the market, will probably be tagged with the most prominent type of safety warning used by the Food and Drug Administration.
According to Pfizer, Bextra can cause a rare but sometimes life-threatening drug reaction called Stevens-Johnson Syndrome in which the skin, mouth, and eyes can become horribly blistered. Other drugs, including Pfizer's arthritis pill Celebrex, can also cause this condition but it seems to be more common with Bextra than other medications. Patients taking Bextra who develop the condition tend to get it in the first two weeks of treatment.
Bextra causes Stevens-Johnson Syndrome more often than Celebrex, a similar Pfizer pain drug, and Pfizer has been in discussions with the Food and Drug Administration about how to include the risk in the drug's label. In its third quarter regulatory filing, the drug giant said these discussions would likely to lead to a 'black box' warning in which warning language is displayed in bold type on a drug's packaging. Pfizer had already communicated the risk to doctors in an Oct. 15 letter.
Timothy Anderson, an analyst at Prudential Equity Group, first reported the likely labeling change in a note to investors Friday night. Anderson noted that many drugs have warnings in their labels about the risk of Stevens-Johnson Syndrome, but few contain a 'black box.' "A 'black-box' warning on Bextra will impair [Pfizer's] ability to market the drug," Anderson wrote, "which suggests the commercial future of Bextra is at risk."
Previously, Anderson had estimated 2005 Bextra sales of $1.7 billion, up from $990 million in 2003. He now believes that number may need to be scaled back. Bextra is in the same class of medicines as Vioxx, the Merck pill that was pulled from the market because it doubled the risk of heart attack and stroke.
Bextra has also been linked heart risk in high-risk patients. Pfizer revealed last month that the drug increased the risk of heart attack in patients who had undergone open-heart surgery in two separate studies. Those results were also included in the October 15 letter to doctors.
The risk did not turn up in other studies of the drug in surgery, and Bextra has not been approved for post-surgical use. Still, Pfizer has also been discussing the open-heart surgery data with the FDA, says Pfizer the product's label. She said that Bextra is still an important option for patients, but said that both side effects, though rare, are serious.
The Vioxx withdrawal has resulted in increased scrutiny for Celebrex and Bextra, which inhibit inflammation in the same way. Prexige, another similar drug being developed by Novartis, has been delayed for at least a year.
In defending Celebrex, Pfizer points to extensive data and the millions of patients who have taken the drug. In a bold move, Pfizer is testing Celebrex in patients at high risk for heart attacks and it says it expects the drug may actually reduce cardiovascular disease.