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New Study Further Links Ephedrine with Heart Attacks

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Scripps Howard News Service

By By LEE BOWMAN

Thursday, October 14, 2004

New animal research being published later this month more closely links the dietary supplement ingredient ephedrine with sudden death from heart attacks.

Dr. Philip Adamson, an associate professor of physiology and cardiovascular disease at the University of Oklahoma Health Science Center, reported on the findings Thursday during a science news conference presented by the American Medical Association.

The federal Food and Drug Administration banned the ingredient from store shelves last spring after it was linked to more than 150 sudden heart attack deaths in recent years, many of them among younger adults with no symptoms of heart disease.

"Ephedrine mimics the sympathetic nervous system, the part of the nervous system that makes the heart beat stronger and faster. In past experiments on obese, otherwise healthy individuals, ephedrine did not raise their heart rates when they were either at rest or exercising," Adamson said.

"When we gave healthy animals ephedrine, we found exactly the same thing. But the moment they developed a blockage in their heart artery, which we are able to cause reversibly in the lab, their heart rates went through the roof," the researcher said. "It was the response to ischemia, a condition where there is a blockage of the heart's blood supply that was exaggerated by ephedrine."

The experiment is being detailed in an upcoming issue of the Journal of the American College of Cardiology.

In ischemic heart disease, blood vessels to the heart become constricted, causing damage to the heart muscle. But sometimes, the condition develops without any symptoms, leading to a sudden heart attack.

"Death can be the first symptom people with ischemic heart disease experience," Adamson said. "We wanted to determine how ephedrine, taken as directed, might cause someone with ischemic heart disease to have a fatal heart attack."

For the study, started before the FDA ban, the researchers went to local health food stores for ephedrine supplements and gave the lab animals doses as recommended on product labels.

"Ephedrine looks benign when you look at it's effects on normal heart rates, but when there is a blockage, boom, ephedrine causes a potentially lethal arrhythmia, the heart starts beating so fast it can no longer pump blood."

Of the 15 animals given the supplement, nine experienced a dangerous and wild beating of the heart and four began beating so fast that the organs could no longer pump blood.

While ephedrine was marketed for many years as a weight-loss aid and enhancer of athletic performance, it was never systematically studied. "As the cardiologist for the university's athletic department, I was interested in researching ephedrine's effects on the body," Adamson said. "I was amazed at the number of student athletes who were taking ephedrine and other supplements without really any idea why they did."

Adamson and colleagues had been studying how the sympathetic nervous system acted to destabilize the heart's electrical system and increases the risk for rhythm disorders, but he noted that despite the reports of adverse reactions, "We didn't expect such a dramatic response to ephedrine. The study certainly supports the FDA's decision."

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Copyright 2004 Scripps Howard News Service

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