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TUESDAY, Nov. 6 (HealthDay News) -- Seventy-five percent of patients taking the widely used blood thinners clopidogrel (Plavix) and prasugrel (Effient) are getting the incorrect dose and could be at risk for serious problems such as uncontrolled bleeding or blood clots, a new study contends.
Millions of Americans with coronary artery disease take the drugs to prevent blood clots that could cause a heart attack or stroke. Guidelines recommend that all patients take the same standardized dose, but that dose is not effective for all patients, according to researchers at the Intermountain Medical Center Heart Institute in Salt Lake City.
The researchers looked at more than 500 patients and found that half of patients taking Plavix were getting too little of the drug to most effectively prevent blood clots, while a quarter were getting too much. Only a quarter were receiving an appropriate dose.
Among patients taking Effient, half were taking too much of the drug, which could lead to dangerous bleeding. A quarter were taking too little of the drug and a quarter were taking the appropriate dose.
The researchers also concluded that indicators like age, gender, cholesterol levels and history of heart problems were not good predictors for how a patient would react to the blood thinners.
"There's a sweet spot, an appropriate range for each patient. But we found that not many people are falling into that range," cardiac researcher Dr. Brent Muhlestein said in an institute news release.
"We showed that by performing a simple blood test to see whether or not the blood is clotting properly, we can determine whether patients are getting an appropriate, individualized dose of the medications," he added. "The test is easy to perform, but not widely used."
The study was presented Tuesday at the American Heart Association annual meeting in Los Angeles. The data and conclusions should be viewed as preliminary until published in a peer-reviewed journal.
The U.S. Agency for Healthcare Research and Quality has more about blood thinners.