Heart surgery patients given anti-bleeding drug Trasylol were more likely to die than patients given another drug or no drug at all, two more studies have found, reigniting controversy over the drug’s safety.

Trasylol, manufactured by Bayer AG and generically known as aprotinin, is a drug used in the coronary artery bypass surgery (or bypass surgery) procedure to prevent a patient from having bleeding complications. As a side effect, severe kidney problems developed with a few cases being life ending. 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.

The drug maker suspended sales of Trasylol last fall, after a Canadian study was halted because of higher incidence of deaths among patients taking it.

Now two more studies arrived to the same conclusion.

One study, looking at more than 10,000 patients who had bypass surgeries at Duke University Medical Care from 1996 through 2005, found that 6.4 percent of patients who were given Trasylol died within 30 days of the surgery, a rate nearly 2 and 1/2 times higher than patients who got another drug or who received no treatment for excessive bleeding. Moreover, almost 16 percent of Trasylol patients died one year after the surgery.

“There continues to be an association between aprotinin and higher death rates and kidney failure,” Dr. Andrew Shaw, and associate professor of anesthesiology at Duke University and lead author of the study said quoted by the Washington Post.

The second study, funded by Bayer, and led by Dr. Sebastian Schneeweiss of Harvard Medical School looked at more than 78,000 people from January 1, 2003 to March 31, 2006. The researchers found the risk of death after surgery was 64 percent higher in the Trasylol group than in those taking another drug or no drug at all.

The pharmaceutical company intentionally withheld the negative results at a September 2006 federal hearing in which the FDA discussed the drug’s safety. Some scientist had said, at the time, the research was flawed and the deaths may have been caused by other factors. Therefore, the committee voted to keep the drug on the market.

Bayer officials said they did not discuss the results of their study because they were preliminary and they had doubts about how it was done.

Bayer already faces lawsuits from federal officials and from patients, for putting a risky medicine in the hands of doctors. It is believed that the lives of 22,000 people would have been spared if the drug had been recalled earlier.

“Had this been done 10 years ago with Trasylol, many lives would have been saved," Dr. Wayne A. Ray, a professor of preventive medicine at Vanderbilt University in Nashville, Tenn. commented in an editorial accompanying the two studies in today’s issue of the New England Journal of Medicine.