The effect could increase the risk of bleeding among those who take both substances, say the physicians from the University of Michigan Cardiovascular Center who made the finding. But the new finding could also help determine why clopidogrel does not work in some people, and aid the search for new drugs to help them.

The researchers caution that much more clinical study will be needed to confirm the effect. For now, they say, the early finding reinforces how important it is for patients to tell their health care providers about all the herbal remedies they take, as well as their conventional prescription drugs and over-the-counter medications.

"Drugs can interact with drugs, and drugs can interact with herbals, and the result in either case can be dangerous," says lead author Wei C. Lau, M.D., a clinical associate professor of anesthesiology who directs adult cardiac anesthesia at the U-M Health System.

He continues, "We are progressively more aware of previously unknown drug-drug interactions as our knowledge in the field of pharmacogenomics expands. The only safeguard against potential harm is for patients to be completely candid with their doctors about what they're taking, and for physicians to be cognizant of the pharmacological mechanisms of drug metabolism that can help dictate vigilance in asking their patients."

The study, which was presented in a poster at the Annual Scientific Sessions of the American College of Cardiology, involved six healthy people who had been selected for their body's low response to clopidrogrel's blood-thinning properties.

The drug is commonly used to prevent heart attacks and strokes by keeping the platelets in the blood from sticking together. But it is known to be ineffective in some people, an
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Contact: Kara Gavin
kegavin@umich.edu
734-764-2220
University of Michigan Health System
6-Mar-2005