Pfizer Inc. announced that its arthritis pain-relieving drug Celebrex has been found to increase the risk of heart problems in patients. Celebrex is in the same COX-2 inhibitor class as Vioxx, the arthritis and pain medication recalled earlier this year due to its heart attack and stroke risk in takers. A government-sponsored study found patients taking Celebrex had more than twice as many heart attacks as patients taking a placebo.

This is the first study to show Celebrex is linked to an increase risk of heart problems. Pfizer said the trial involved patients taking 400-milligram and 800-milligram daily doses of Celebrex to prevent adenomas, tumors that grow from glandular tissue. The anti-inflammatory drug was being tested on the theory that inflammation is a cause of cancer.

A second study being conducted by Pfizer has not shown any increased risk. This long-term trial was designed to see if the drug could prevent colon polyps. The company was conducting the two trials as part of an effort to find a new application for the drug.

Celebrex is currently approved for use in the United States for the treatment of arthritis and pain.

Previous warnings

Another Pfizer drug, Bextra, was found to increase heart problems associated with the use of the drug in people who have recently had heart bypass surgery. Earlier this month, the Food and Drug Administration added a warning label to the drug warning of this potential danger.

Bextra, Celebrex and Vioxx are all in a class of pain drugs called cox-2 inhibitors. The drugs have become popular because of their effectiveness in treating the pain of arthritis and other ailments. They work by selectively blocking the Cox-2 protein that has been linked to inflammation.

These new findings come only 10 weeks after the withdrawal of fellow cox-2 inhibitor Vioxx after a study found the drug doubled the incidence of heart attack and stroke among patients taking it to prevent colon polyps that cause cancer.

Patients taking the painkiller are advised to contact their doctors.

"In light of this discouraging news, individuals who are taking either Celebrex or Bextra should immediately contact their physician," said Dr. Mark Fendrick of the University of Michigan.

So far this year, there were 19.8 million prescriptions filled for Celebrex, 10.9 for Bextra; and 14 million for Vioxx, according to IMS, a pharmaceutical consulting company.

"This does not bode well for COX-2 inhibitors in general," said Ira Loss, an analyst at Washington Analysis. "The sense had been that Celebrex is somehow different from the others."

In October, sales of the Pfizer Inc. drug Celebrex topped $260 million, or 63.5 percent of the market for cox-2 inhibitors, according to IMS Health data.

Studies done five years ago - when Celebrex and Vioxx were approved - suggest the same mechanism that inhibits inflammation and makes the drugs easier on the stomach also blocks a substance that prevents heart problems, scientists have said.