November 30, 2004
Celebrex Benefits From Vioxx Withdrawal
WASHINGTON - Pfizer's Celebrex gained a majority of sales for new-generation painkillers in the month after Merck & Co. yanked Vioxx due to safety concerns, according to IMS Health, a pharmaceutical information company.
Pfizer's other cox-2 inhibitor, Bextra, gained fewer prescriptions in October, and in November confronted heightened scrutiny of its safety.
Merck faces a flood of lawsuits after Vioxx was linked to increased risk of heart attack and stroke and the company withdrew it from the market Sept. 30. Analysts estimate the company's legal liabilities could reach $18 billion.
In October, the first full month of data after the Vioxx withdrawal, sales of Celebrex topped $260 million, or 63.5 percent of the market for cox-2 inhibitors, according to IMS Health data. In September, Celebrex had accounted for 48.7 percent of the market for the new-generation painkillers.
Bextra sales in October totaled $148 million or 36 percent of the $409 million cox-2 inhibitor market. In September, Bextra had 23.5 percent of that market.
For the first 10 months of 2004, Celebrex remained the top selling cox-2 inhibitor with 19.8 million prescriptions filled. Sales of Bextra, by contrast, totaled 10.9 million prescriptions in the same time period.
Sales of nonsteroidal anti-inflammatory painkillers such as Mobic and Synvisc showed an uptick in October as well. Such painkillers accounted for $125 million in sales in October, compared with $115 million in September. In the first 10 months of 2004, sales of those painkillers grew by 12 percent over the same time period in 2003, according to IMS Health.
Rheumatologists had expressed some wariness about prescribing Bextra to patients, fearing it caused the same type of heart woes as Vioxx.
Dr. Hayes Wilson, chief rheumatologist at Piedmont Hospital in Atlanta, like others in his specialty, is now reluctant to prescribe Bextra to patients with such risks as advanced heart disease. But the drug still is an attractive therapy for patients who tried other new-generation painkillers, such as Celebrex, without success.
"There is not a great worry and concern about Bextra," said Wilson, who is also a national medical adviser for the Arthritis Foundation. "We do want to do what's best for our patients and to make sure we are doing what is safest. We're not ignoring the information that is coming out about Bextra. However, scientifically, I don't think there is anything that has been proven at this point."
When they came onto the market, the cox-2 inhibitor drugs were praised for blocking the enzyme that causes the pain and swelling of arthritis inflammation. The drugs, however, were selective in their targets, and helpfully bypassed the cox-1 enzyme that helps the stomach maintain a protective lining.
A preliminary study discussed at the American Heart Association's annual meeting in early November indicated Bextra more than doubled the risk of heart and stroke among heart disease patients taking the painkiller.
Pfizer dismissed that study's findings in a press release, calling them "unsubstantiated conclusions" that had not been subjected to independent scientific review. The company, however, alerted regulators that it will add to its packaging a black box warning - the Food and Drug Administration's most strident alert - to warn consumers of a potentially fatal skin reaction linked to Bextra.
An FDA advisory committee in mid-February will review all available data on cox-2 inhibitors, including Bextra, Celebrex and Vioxx.
The data includes a placebo-controlled trial involving 3,600 patients that tries to determine whether Celebrex prevents colon polyps and another that tests the popular painkiller as a possible Alzheimer's treatment.
Independent panels reviewing those trials have not yet seen signs that Celebrex is as harmful to the heart as Vioxx.
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