If Merck puts painkiller Vioxx back on the market after removing it because of safety concerns, it would be an unusual but not unprecedented event.
Among drugs approved by the Food and Drug Administration since 1990, 14 have been withdrawn from the U.S. market for safety reasons, says consumer watchdog group Public Citizen. Only Lotronex, approved to treat irritable bowel syndrome in women, has so far been reintroduced.
That happened in 2002, two years after Lotronex went off the market and only after the FDA restricted its use. Merck might likewise face restrictions on Vioxx, and that might make a re-launch unattractive, says Winton Gibbons, health care industry analyst with investment bank William Blair.
"It may not be economically advantageous," he says.
Merck pulled Vioxx from the market Sept. 30 after a study showed it increased cardiovascular risks for some users.
Last week, an FDA advisory panel decided that painkillers Vioxx, Celebrex and Bextra carry cardiovascular risks but recommended that the FDA support their being marketed. Merck suggested it would consider putting Vioxx back on the market if the FDA approved and if competing drugs stayed on the market.
What happened to Lotronex might dampen enthusiasm. The drug was pulled from the market in 2000, less than a year after it got FDA approval, by maker Glaxo Wellcome because of reports of severe gastrointestinal side affects. Glaxo and the FDA also couldn’t agree on how to manage the risk.
The drug’s removal caused an outcry from consumers. They lobbied the FDA, saying they would accept the drug’s risk to get the benefit. An FDA advisory panel recommended it be returned to market with restrictions, which the FDA did in 2002. It restricted the drug to women with severe symptoms and for whom other treatments failed. Among other things, patients have to sign consent forms indicating they’re aware of potential risks. Doctors must enroll in a program to assure they understand them.
GlaxoSmithKline, formed from a merger, doesn’t break out Lotronex revenue because it’s not one of the company’s biggest-selling drugs. But its universe of users has shrunk.
From March 2000 to the following December, 534,000 Lotronex prescriptions were written for 275,000 patients, Glaxo says. From November 2002, after its return, to February 2004, only 35,000 prescriptions had been written for 10,000 patients.
Last week’s FDA panel indicated a preference for all three painkillers to carry labels detailing their heart risk and for a ban on consumer advertising. The FDA’s response is expected within weeks. It typically follows its panels’ recommendations.
Several panel members also said Vioxx should only be available for pediatric use since it’s the only one of the three so approved by the FDA. A handful of members suggested patient consent forms be required, and several recommended limiting Vioxx to patients for whom other drugs don’t work.
"When you put all of those together … it could be a small market," says Gibbons, who personally owns shares of Pfizer, maker of Celebrex and Bextra. Vioxx revenue hit $2.5 billion in 2003, and was one of Merck’s biggest drugs.
Marketing experts, too, say it’ll be tough for any of the drugs to woo back consumers who have found other options that work and carry less risk. For those who haven’t, not even a strong warning label is likely to deter them unless they’re in a high-risk group, says Pam Scholder Ellen, associate professor of marketing at Georgia State University. They might say, "Yes there is a danger but it’s not going to happen to me," she says.
The panel’s vote on Vioxx was 17-15; Bextra 17-13; Celebrex 31 to 1. The Vioxx vote, though largely split, might help Merck’s defense against hundreds of lawsuits alleging that it knew long before it pulled Vioxx of its risks – an allegation it denies. Andy Birchfield, one of the lead plaintiffs’ attorneys, on Monday called on Merck to keep Vioxx off the market.