Could Genetics Improve Warfarin Dosing?
News Feb 24, 2009
In a large-scale study and an upcoming clinical trial, scientists supported by the National Institutes of Health address one of the trickiest issues in prescribing medicine - how to quickly optimize each patient's dosage of the common blood-thinning drug warfarin.
One of the most widely prescribed drugs in the world, warfarin is used to prevent dangerous blood clots that can lead to heart attacks, strokes or even death. The drug is challenging for doctors to prescribe because the ideal dosage for each person varies widely and is hard to predict, yet is crucial for the patient's safety.
Every year, an estimated 2 million Americans with certain heart conditions or other risk factors start taking warfarin. Getting the wrong amount of warfarin can be dangerous -- if the dose is too high, patients could bleed profusely; if it's too low, they could develop life-threatening clots.
Using information from thousands of genetically and geographically diverse patients, an international team of researchers developed a way to use genetic information from patients that could help doctors better determine optimal warfarin doses. The results of the analysis are published in an article titled "Warfarin Dosing Using Clinical and Pharmacogenetic Data" in the Feb. 19 issue of The New England Journal of Medicine.
The article is accompanied by an editorial by Janet Woodcock and Lawrence Lesko of the Center for Drug Evaluation and Research at the Food and Drug Administration.
In an important step toward putting these findings into clinical practice, NIH is launching the largest prospective, multi-center, randomized clinical trial in the United States to test whether a gene-based strategy for prescribing the initial warfarin dose will improve patient outcomes. The clinical trial will use a dosing strategy similar to that developed in the international study. The trial will enroll 1,200 participants of diverse backgrounds and ethnicities at twelve clinical sites, and is scheduled to begin next month.
"In these investigations, NIH-funded basic research and clinical trials are working hand in hand to improve the care of the millions of patients on warfarin therapy," said Raynard S. Kington, M.D., Ph.D., acting NIH director. "More broadly, these efforts showcase NIH's firm commitment to building a future of personalized medicine - a future in which doctors will be able to prescribe the optimal dosage of medicine for each patient right from the start."