DNA Tests to Determine Warfarin Dose

The Associated Press
Friday, January 12, 2007; 8:02 PM

TRENTON, N.J. -- Personalized medicine, the tailored treatments that a few patients now get based on their own DNA, is finally headed for the masses: the many heart patients at risk of deadly blood clots.

At least 2 million Americans with an abnormal, clot-triggering heart rhythm take the pill warfarin, also sold as Coumadin.

Getting too little can lead to a stroke, and too much can cause life-threatening bleeding. To find the right dose for each patient, doctors use trial and error _ and the errors lead to tens of thousands of hospitalizations and deaths every year.

Starting this month, about 1,000 patients who have a condition known as atrial fibrillation will take part in a project that will match their Coumadin dose to their specific genetic needs.

This genetic fingerprinting should single out the many people whose bodies break down warfarin faster or slower than normal, and their doctors can immediately adjust their dosage to prevent dangerous complications.

"Twenty to 30 percent of people are either very fast or very slow" to metabolize many drugs but don't know it, said Dr. Robert Epstein, chief medical officer at prescription benefit manager Medco Health Solutions of Franklin Lakes, N.J., which is collaborating in the effort with the Mayo Clinic, based in Rochester, Minn.

Meanwhile, the federal government and researchers at Harvard University and elsewhere have begun or are planning similar studies.

Epstein and other experts say the warfarin projects comprise the first broad use of personalized medicine, or targeted therapy, in which a person's genetic makeup is used to pick the best medicine or dose. This approach essentially adjusts for differences in body chemistry that explain why one pain reliever or allergy pill works great for you but not for your mom.

"It's a big deal," said Edward Abrahams of the Personalized Medicine Coalition, which includes industry, government and patient advocacy groups as well as insurers and research centers. "Warfarin is a very widely used drug, it's been around for 50 years and it has all these adverse events associated with it."

If the warfarin studies are successful, patients will start demanding personalized medicine, he predicted. Insurers will, too, if the Medco study proves it saves money and protects patients.

That's fairly likely, given Medco data showing that if patients have their warfarin dose changed more than once _ meaning doctors didn't get it right the first two tries _ their risk of being hospitalized for complications jumps from 20 percent to 31 percent.

Epstein said he's hit "a home run" with his pitch to get employers and insurance companies sponsoring the prescription plans to join the study.

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