New Clotting Drug Fails in Trial

Heparinase I study stopped early due to side effects

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MONDAY, Aug. 1, 2005 (HealthDay News) -- A new anti-blood-thinning drug called heparinase I is not a safe replacement for an old standby, protamine, according to a new study.

Protamine has been used for more than four decades to reverse the effects of the blood-thinning drug heparin and return thinned blood to its normal state after a patient has had coronary artery bypass surgery. However, recent studies have found that protamine can cause blood pressure changes that may increase a patient's risk of death. Protamine can also depress heart function, activate certain immune responses and lead to pulmonary hypertension.

Heparinase I is the latest potential replacement drug for protamine. However, a recent Phase IIB/IIIA safety and efficacy trial on heparinase I conducted at 47 sites in the United States, Canada and Germany was stopped early because patients taking the drug experienced negative side effects such as infections and bleeding.

The trial was stopped after it had enrolled 167 of 600 planned participants.

"The trial was designed to determine if this new drug could work as well as protamine, without its known side effects," study lead author Dr. Mark Stafford-Smith, a cardiovascular anesthesiologist at Duke University Medical Center in Durham, N.C., said in a prepared statement.

"However, after reviewing the safety profiles during the trial, the data safety monitoring board decided to stop the trial," Stafford-Smith said.

"The design of the trial was such that it not only allowed us to spot problems early in the process but gave us the confidence in our decision that heparinase I would not be a suitable replacement for protamine. However, we do need to continue our efforts to develop an effective alternative," he said.

The findings were reported in the August issue of the journal Anesthesiology.

More information

The American Medical Association has more about bypass surgery.

SOURCE: Duke University Medical Center, news release, Aug. 1, 2005

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