Common Clot-Buster May Have a Superior

Variation of heparin effective and easier to use

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HealthDay Reporter

TUESDAY, July 6, 2004 (HealthDayNews) -- A newer form of the clot-preventing drug heparin appears to offer some advantages for patients hospitalized for heart attacks and other acute heart conditions, new studies indicate.

The drug, enoxaparin, was at least as effective as heparin at reducing complications and deaths for those patients, according to three studies appearing in the July 7 issue of the Journal of the American Medical Association.

"When you look at the systematic overview, which is really a compilation of data on 20,000 patients, enoxaparin appears more effective in reducing events such as deaths and subsequent myocardial infarctions [heart attacks]," said Dr. Kenneth Mahaffey, an associate professor of medicine at Duke University Medical Center, who led one of the trials.

And enoxaparin is much more convenient for both patients and medical staffers than heparin, Mahaffey said, offering advantages that can more than offset its higher cost.

Heparin is given intravenously, which means a patient must have a tube inserted for a continuous drip, and periodic blood tests are needed to monitor its effectiveness. Enoxaparin is given by injection, twice a day, and does not require such monitoring, Mahaffey said.

While the new reports do not cover the cost of treatment, at least one previous study found that "enoxaparin is really cost-effective and may be cost-saving," he said.

Enoxaparin is actually a fraction of the heparin molecule. Like the complete heparin molecule, it blocks the action of thrombin, an enzyme important in the formation of blood clots. Patients hospitalized with acute coronary conditions such as heart attacks are given heparin to prevent potentially fatal blood clots, usually as soon as they arrive at an emergency room.

Studies do not say that patients who are started on heparin should be switched to enoxaparin, which means that switching to the newer drug requires a basic change in emergency room procedures, Mahaffey said.

"At Duke, we are being more aggressive at integrating enoxaparin into treatment of patients at high risk," he said. "What we are pushing for is that the emergency room move to enoxaparin as the backbone of therapy."

But there are complicating factors that must be taken into account, said Dr. David J. Moliterno, chief of cardiology at the University of Kentucky and co-author of an accompanying editorial in the journal. One is that the new studies failed to show major benefits for enoxaparin vs. heparin, he said.

Another is that hospitals now are performing artery-opening procedures more quickly for patients with acute coronary conditions, Moliterno said, which lessens the advantages of enoxaparin.

Patients now get those treatments within 48 hours, so close monitoring of heparin is less necessary, he said.

And the clot-preventing activity of heparin can be reversed quickly, while that of enoxaparin cannot, Moliterno said, which is an important consideration if bleeding begins. The study led by Mahaffey showed more incidents of major bleeding for patients who got enoxaparin, he noted.

There is a place for enoxaparin in treating acute coronary conditions, but the case for it is not overwhelming, Moliterno said.

"For those who are already accustomed to [using] it, there is no evidence that they can't go on using it," he said. "For those who don't use it, these studies offer further evidence that it does not give as much benefit as previously thought."

More information

Read about how heparin is used from the National Library of Medicine.

SOURCES: Kenneth Mahaffey, M.D., associate professor of medicine, Duke University Medical Center, Durham, N.C.: David J. Moliterno, M.D., chief of cardiology, University of Kentucky, Lexington; July 7, 2004, Journal of the American Medical Association

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