WASHINGTON -- Two studies released yesterday have turned up new evidence that all of the popular arthritis painkillers known as cox-2 inhibitors may put users at greater risk of heart attacks and strokes.
The first of the two papers published online by the journal Circulation found that patients who had had heart bypass surgery and were taking Pfizer Inc.'s Bextra, in combination with an experimental medication, were three times more likely to have strokes and heart attacks than patients taking a placebo. The statistically significant tripling of the risk showed up when researchers combined the results of two earlier studies involving more than 2,000 people in a statistical technique called meta-analysis.
A second study found that when mice that are genetically prone to hardening of the arteries were treated with a cox-2 drug and an aspirin substitute, their condition worsened rather than improved, as researchers had anticipated.
Lead researcher Garret A. FitzGerald of the University of Pennsylvania said the two studies led him to conclude that the entire class of drugs poses a risk. He also said an upcoming clinical trial proposed by Pfizer, the maker of Celebrex, to test whether that drug may help patients with heart disease should not go forward.
''The clear emergence of a cardiovascular hazard from cox-2 inhibitors in patients, the weak rationale for a study of their protective properties in the first instance, and now this evidence from mice would indicate to me that a trial in high-risk patients, such as that proposed for Celebrex is, at best, ill advised," said FitzGerald, a longtime skeptic of widespread cox-2 use.
A Pfizer spokeswoman said yesterday that company officials could not comment because they had not seen the studies.
The latest bad news for makers and users of cox-2 drugs comes a month before the Food and Drug Administration is scheduled to hold an unusual three-day hearing of two advisory panels to consider safety issues that have arisen around the class of drugs.