Merck & Co. released preliminary results of a large-scale study that suggested that an arthritis medicine it hopes will replace Vioxx on pharmacy shelves may not carry any more heart risks than an older, widely prescribed drug.
But the company's statement, which didn't include some basic information about the study, also flagged some potential worries for the drug, including higher rates of hypertension and other conditions that caused some patients who were taking it to drop out of the trial. And some scientists raised questions about the study's design.
The painkiller, Arcoxia, is sold in Europe and Latin America but hasn't been approved for sale in the U.S. In October 2004, the Food and Drug Administration responded to Merck's application for approval by asking for more information - Merck drug pipeline at Drug Pipeline Database. Merck executives yesterday said they plan to submit the study as part of their response to the agency.
The preliminary results released by the Whitehouse Station, N.J., drug maker are part of a study known as Medal, a 34,700-patient arthritis-drug study that is the first to primarily examine the cardiovascular effect of Arcoxia and diclofenac, an older arthritis treatment. Both belong to the class of drugs known as non-steroidal anti-inflammatory drugs (Nsaids). Arcoxia is a so-called Cox-2 inhibitor, as are Vioxx and Celebrex, made by Pfizer Inc., and which are meant to be safer on the stomach than aspirin and other painkillers.
Merck withdrew Vioxx from the market in September 2004 after a study linked it to an increased risk of heart attacks and strokes. In February 2005, an FDA advisory panel recommended cardiovascular warnings on all prescription Nsaids. Merck now faces roughly 14,200 lawsuits over Vioxx.
If Merck gets the green light to sell Arcoxia in the U.S., the drug could replenish lost Vioxx sales -- though its overseas sales in the first half of this year were only $126 million. Merck's preliminary findings suggested that there is no significant difference in the cardiovascular risks of Arcoxia and diclofenac. But Merck also said that greater numbers of certain Arcoxia patients had to discontinue treatment due to problems related to high blood pressure, edema and congestive heart failure. The drug's European label carries a warning about these conditions.
Steven E. Nissen, chairman of cardiovascular medicine at the Cleveland Clinic, and a critic of how Merck released data on Vioxx's heart risks, said the company's Arcoxia announcement "is a very limited amount of data" and doesn't provide a complete picture of the drug's risks and benefits. Among other things, the company didn't say how many people suffered heart attacks, he noted.
Merck said it plans to release the full results of the study once they are published in a peer-reviewed journal.
Critics also questioned the study's design, especially the use of diclofenac as the comparison treatment. Diclofenac, Dr. Nissen said, acts in the body more like Cox-2 inhibitors than painkillers such as naproxen. Thus, he suggested, it is possible that Arcoxia would look safer from the standpoint of heart risk against diclofenac than against naproxen. "To really know whether [Arcoxia] is neutral or increases cardiovascular event rates, we would need to see a comparison to an agent like naproxen," he said.
"Most people didn't expect a difference" between Arcoxia and diclofenac," said Curt D. Furberg, a Wake University public-health professor. While Dr. Furberg lauded the size of the study, he said, "the take-home message is stay away from diclofenac. The Cox-2 drugs have harmful effects and this study documented that diclofenac is no safer."
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