NEW YORK, Dec 17 (AFP) - Drug giant Pfizer shares plummeted 14.6 percent Friday after a trial showed a higher heart attack rate for patients on its blockbuster Celebrex arthritis and pain medicine.
The risks only appeared in one of two studies.
"These clinical trial results are new. The cardiovascular findings in one of the studies are unexpected and not consistent with the reported findings in the second study," Pfizer chairman and chief executive Hank McKinnell said in a statement.
Pfizer shares plunged 4.23 dollars, or 14.59 percent, to 24.75 in the first 15 minutes of trade.
A study into prevention of benign tumours, or adenomas, showed patients taking 400mg and 800mg of Celebrex daily had an approximately 2.5 fold increase in their risk of experiencing a major fatal or non-fatal cardiovascular event compared to those patients taking placebo, according to the National Cancer Institute (NCI).
Based on the "statistically significant" findings, the sponsor of the trial, the NCI, suspended the dosing of Celebrex. The news was given to Pfizer late Thursday.
A separate study, however, into the prevention of polyps, showed no increased risk for Celebrex patients taking 400mg daily compared with those taking placebo.
Pfizer rival Merck had already announced a global withdrawal of a similar "COX-2 inhibitor" drug, Vioxx, on September 30, prompted by a study showing it increased the risk for strokes and heart attacks. Merck's share price has crumbled and it is now engulfed in lawsuits.
Until now, Pfizer's Celebrex -- used by 26 million people according to the Pfizer Internet site -- had not been shown to produce any increased risk of heart attacks.
"Pfizer is taking immediate steps to fully understand the results and rapidly communicate new information to regulators, physicians and patients around the world," McKinnell said.
Celebrex is approved for use in the United States for the treatment of arthritis and pain, at recommended doses of 100mg to 200mg daily for osteoarthritis and 200mg to 400mg a day for rheumatoid arthritis.
The results of the adenoma study, known as the APC trial, differed from the second study and from "the large body of data that we and others have accumulated over time, in which an increased risk of serious cardiovascular events in arthritis patients, even at higher-than-recommended doses, had not been seen," said Pfizer president for worldwide development Joseph Feczko.
"Celebrex is an important medicine that provides necessary pain relief to many patients. Patients being treated with Celebrex should discuss appropriate treatment options with their healthcare professionals."
12/17/2004 15:05 GMT - AFP