Another Look at Merck’s Painkiller Vioxx and Other Cox-2 Inhibitors

A study published in the journal Lancet, written by Dr. Robert Bresalier of the M.D. Anderson Cancer Center at the University of Texas and colleagues, reveals that a long-term analysis of patients who had been administered Merck & Co´s arthritis painkiller Vioxx, as well as an in-depth analysis of the company´s own trials with this drug, showed that their findings confirmed the drug doubled the risk of strokes and heart attacks, but the risk had gone away about a year after the patients stopped taking it.

Drug maker Merck & Co had to withdraw the popular painkiller from the market in 2004 after safety data from their study set off alarms that Vioxx increased the risks of heart attacks and stroke.

A 2005 analysis by Bresalier and colleagues published in the New England Journal of Medicine suggested that it took 18 months for the drug to increase the risk of heart attacks and strokes, a time frame that played a prominent role in Merck's legal defense of Vioxx (rofecoxib). The journal later posted a correction on its website, saying the difference was not statistically significant.

The new analysis, done with independent statisticians, suggests the risk occurs early and persists, Bresalier said, then goes back toward normal after a year of follow up.

Bresalier also stated a number of studies since the initial safety warning on Vioxx suggest other Cox-2 inhibitors, including Pfizer Inc's Celebrex (celecoxib), and non-steroidal anti-inflammatory drugs (NSAIDS) such as ibuprofen, also carry a higher risk of heart trouble.

"I think the preponderance of data now does suggest this is a class effect," Bresalier said.

Cox-2 drugs were designed to be safer replacements for NSAIDS, including aspirin and naproxen, which can cause deadly gastrointestinal bleeding.

Last year, Merck made a $ 4.85 billion dollar deal to settle thousands of claims for heart attacks, strokes and deaths allegedly caused by the drug.

Vioxx had generated sales of $ 2.5 billion dollars a year before it was withdrawn from U.S. drugstores almost four years ago. Pfizer's Celebrex has remained on the market, and in the first six months of this year had sales of $ 1.2 billion dollars.