Merck's Vioxx Successor Has Its Detractors

Drug manufacturer Merck is applying for FDA approval of Arcoxia, a painkiller that it hopes will replace Vioxx. But is Arcoxia safer than Vioxx, which was taken off the market after being linked to heart problems?

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The painkiller Vioxx was pulled from the market more than two years ago because it increases the risk of heart attack and stroke. Now its manufacturer has a drug from the same family that it wants the Food and Drug Administration to approve. But critics say the drug may have as many problems as Vioxx, if not more.

NPR's Joanne Silberner reports.

JOANNE SILBERNER: Once a brand new drug is developed, other companies, and even the original manufacturer, start working on other versions, tweaking the chemical compound in the hopes of coming up with something more effective, something safer, something better. Merck hopes it has something better in Arcoxia. Dr. Scott Korn heads worldwide regulatory affairs at the company.

Dr. SCOTT KORN (Merck Executive): Patients and physicians need another option to treat arthritis, and we think that there's a place in the marketplace for our drug, which will fill that unmet medical need.

SILBERNER: But Dr. Steven Nissen thinks patients are better off with other painkillers in the class of drugs known as NSAIDs. Nissin is head of Cardiovascular Medicine at the Cleveland Clinic. He led the charge against Vioxx and he says Arcoxia offers no advantages.

Dr. STEVEN NISSEN (Chairman, Department of Cardiovascular Medicine, Cleveland Clinic): There is not one shred of data to suggest that it's more effective at relieving pain than the other drugs that are on the market.

SILBERNER: But does he think it's safer?

Dr. NISSEN: Well, I don't think there's much evidence that it is even as safe as existing drugs, let alone safer.

SILBERNER: Merck's contention that the drug is safe is based on studies comparing thousands of patients taking Arcoxia to thousands taking an older painkiller called diclofenac.

Dr. NISSEN: The problem is that in very large-scale studies, diclofenac looks about as risky as Vioxx. So finding out that the new drug, Arcoxia, is not different than diclofenac does not inspire confidence and certainly does not prove safety.

SILBERNER: Merck's Dr. Korn says diclofenac is an appropriate drug for comparison.

Dr. KORN: It's effective for both osteoarthritis and rheumatory arthritis. Diclofenac is actually the most widely prescribed NSAID in the world.

SILBERNER: Scientists at the FDA have analyzed the studies on Arcoxia and they say the drug is more likely than diclofenac to raise blood pressure and increase the risk of heart failure. Scott Korn of Merck says lower doses may take care of that problem.

This Thursday, an FDA advisory committee will weigh the evidence and make recommendations for or against approval. The agency itself is scheduled to make a decision by the end of the month. As for people with chronic pain, the American Heart Association recently published guidelines about how to treat pain most safely. Dr. Elliott Antman, head of the cardiac care unit at Brigham and Women's Hospital in Boston, chaired the committee that wrote the guidelines.

Dr. ELLIOTT ANTMAN (American Heart Association): We start with the drugs that we believe are least risky, and that would include aspirin and acetaminophen. And then we move to cousins of aspirin, called nonacetylated salicylates. And once we move pass those first two steps, we enter a zone, which I refer to as the danger zone.

SILBERNER: In the danger zone, they recommend first naproxen. If that doesn't work, then ibuprofen or diclofenac. There's only one Arcoxia-like drug currently on the market - Celebrex - and Heart Association says that should only be a last resort.

Meanwhile, investigators at 800 hospitals worldwide are comparing the safety and effectiveness of naproxen, ibuprofen and Celebrex, but the results aren't due for about three years.

Joanne Silberner, NPR News, Washington.

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