The drug giants announced on Friday that it had found an increased risk in one of two long-term cancer prevention trials. Pfizer were conducting the trials as a project to find new applications for the drug.
In the (the APC cancer trial), patients taking 400mg to 800mg of the drug daily were found to have a risk of 2.5 times greater of experiencing heart problems than those who weren't. A separate cancer study (the PreSAP cancer trial) found no increased heart risk with patients taking 400mg of Celebrex per day.
Pfizer said it had no plans to withdraw the drug from the market. Celebrex is currently approved for use in the United States for the treatment of arthritis and pain.
In a statement on its website, Hank McKinnell, Pfizer chairman and chief executive officer said: "Pfizer is taking immediate steps to fully understand the results and rapidly communicate new information to regulators, physicians and patients around the world."
"These clinical trial results are new. The cardiovascular findings in one of the studies (the APC cancer trial) are unexpected and not consistent with the reported findings in the second study (the PreSAP cancer trial)."
Dr. Joseph Feczko, president of worldwide development for Pfizer was keen to stress that it was important to understand the APC trial results differed from both the PreSAP cardiovascular results as well as the large body of data that Pfizer and others have accumulated over time. He noted that an increased risk of serious cardiovascular events in arthritis patients, even at higher-than-recommended doses, had not been seen.
Pharmaceutical companies have recently been criticised for its secretive practices when disclosing sensitive information. Pfizer's voluntary release of this potentially damaging data could be seen as a way of easing fears over the safety of cox-2 inhibitors and essentially pre-warning the public of the drug's performance, even though it is conflicting.
Pfizer has once again, appeared in the spotlight in which one of its products has come under intense scrutiny. Earlier this month, the Food and Drug Administration (FDA) recommended the addition of warning labels to its drug, Bextra, indicating its link to potential heart problems in patients who recently had bypass surgery.
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.
Merck pulled Vioxx from the market Sept. 30 after a study indicated the popular pain reliever doubled the risk of heart attacks and stroke when taken for longer than 18 months.
The company faces a huge legal liability bill over the withdrawal of the drug, which has been prescribed to millions of patients since it was first introduced in 1999. Analysts have been estimating that the ultimate legal cost to Merck could be in the $15-$18 million range, with one, Sanford Bernstein's Richard Evans, predicting it could go as high as $38 billion (€28.3 billion). 475 lawsuits have already been filed alleging damage from use of the drug.
According to IMS Health data, sales of the Pfizer Inc. drug Celebrex, in October, topped $260 million (€194 billion), or 63.5 per cent of the market for cox-2 inhibitors.