Genes determine blood thinner dosage

The correct dosage for a popular blood thinner used to prevent heart attacks and strokes can be better calculated using a patient's genetic makeup.

Researchers at the University of North Carolina at Chapel Hill and other centers found that patients with certain genetic traits are more sensitive to the drug, called warfarin, while others are less sensitive.

The findings are important because the drug, which is sold under the commercial name Coumadin, was originally a rat poison, so the wrong dose can result in either bleeding, or clotting. Doctors have typically relied on trial and error, but a genetic test could take the guesswork from the process.

“The promise of genetic testing is getting the right drug in the right amount to the right person at the right time every time,” said Howard McLeod, director of UNC-CH's Institute for Pharmacogenomics and Individualized Therapy. The study, he said in a prepared statement, is a big step toward that goal.

Findings were reported today in the New England Journal of Medicine.