Pfizer has issued a warning that its popular pain killer Bextra could increase the risk of heart attack or stroke in patients who have undergone heart bypass surgery.
Bextra is a COX-2 inhibitor, as is Vioxx, withdrawn by Merck earlier this month after studies showed it increased the risk of heart attack or stroke in patients who took it longer than 18 months.
In its warning to doctors, Pfizer said a clinical study of 1,500 patients showed that those who had undergone coronary bypass surgery and taken Bextra intravenously and orally were at high risk for heart attacks. A similar study last year reached the same conclusion.
Vioxx, Bextra and other popular COX-2 inhibitors, including Pfizer's Celebrex, are widely prescribed for patients suffering from arthritis and other painful conditions. Celebrex is the best-selling COX-2 drug. Bextra is a newer, faster-acting version of Celebrex.
Pfizer said it is now conducting tests to determine whether Bextra increases heart attack risk in patients who take it for chronic pain.
The latest warnings contradict Pfizer's earlier assurances that its COX-2 drugs are safe. On October 7, the company said clinical trails had shown that Celebrex does not pose the same risks as Vioxx and said patients have no reason to be concerned.
In fact, the study that demonstrates the Bextra problem was conducted last spring.
Pfizer repeated its contention yesterday that Bextra and Celebrex are chemically different from Vioxx and do not carry the same risks.
The U. S. Food and Drug Administration (FDA) said it will convene a meeting of experts in January to consider safety concerns involving Bextra and Celebrex.
