Heart surgery patients were more likely to die if given the antibleeding drug Trasylol, two more U.S. studies have found, renewing the claims that the drug is dangerous.
Bayer AG stopped selling the drug last fall, after a Canadian study was halted because of deaths among patients taking it.
But the new research reignited controversy over Trasylol, which was on the market for 14 years and used by doctors to treat hundreds of thousands of heart bypass patients each year.
Bayer funded one of the two new studies and had the preliminary results before a September 2006 federal hearing on the drug's safety - but did not present them.
The company issued a statement this week saying both the new studies are flawed. But the spokesman for a consumer advocacy group said the studies are convincing confirmation of the drug's dangers.
"I just don't know how much further evidence you need," said Dr. Sidney Wolfe of Public Citizen's Health Research Group.
The studies are being printed this week in the New England Journal of Medicine.
Trasylol, known generically as aprotinin, was used in heart bypass surgeries to control bleeding. The U.S. Food and Drug Administration approved it in 1993 after studies showed its clotting powers clearly reduced the need for blood transfusions, and it became a top choice for surgeons.
Bayer officials still say they believe Trasylol's benefits outweigh its risks when used properly.