Warfarin Pharmacogenetics: A Rising Tide for its Clinical Value
Warfarin has been in clinical use for nearly 60 years, and in 2010 there were over 25 million prescriptions for warfarin in the U.S. While warfarin is highly efficacious, it has a narrow therapeutic window to achieve desired anticoagulation without excess risk of bleeding. Anticoagulation status is monitored with the International Normalized Ratio (INR), where the most common target INR is 2 to 3. Not only does warfarin exhibit a narrow therapeutic index, but there can be 10 to 20-fold differences in the warfarin dose required to achieve target INR. Thus the early period after warfarin therapy initiation requires frequent INR monitoring to determine the proper dose for the patient, is often associated with multiple dose adjustments, and many patients experience prolonged periods of over- or under-anticoagulation while the appropriate dose is identified. These challenges lead warfarin to be a leading cause of emergency room visits and hospitalizations for an adverse drug reaction, and lead to significant underuse of the drug in patients for whom it is strongly indicated, particularly those with atrial fibrillation.1 (SELECT FULL TEXT TO CONTINUE)
- Received March 12, 2012.
- Accepted March 14, 2012.
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