A genetic test is being used to determine the proper dosage of the blood thinner warfarin in patients at the University of Illinois Hospital & Health Sciences System. The medical center is one of the first in the nation to use genetic information in order to cater to individual patients’ specific dosages of a drug that ranks among the leading causes of drug-related adverse events.
Warfarin is an anticoagulant that has been on the market for more than 50 years. It is used to treat deep vein thrombosis and pulmonary embolism and to prevent stroke in patients with atrial fibrillation or who have had heart valve replacement. The drug is difficult to dose and is usually begun at similar amounts for all patients.
Warfarin carries a black box warning from the Food and Drug Administration (FDA) because of its bleeding risk. Patients who are prescribed warfarin must be monitored on a regular basis to prevent serious and potentially deadly internal bleeding events.
All blood thinners carry a risk of bleeding, which has prompted researchers to develop novel new anticoagulants such as Pradaxa. In 2010, Pradaxa was approved by the FDA to prevent strokes in atrial fibrillation patients. The drug showed promise as a safer alternative to warfarin, but in 2011, a review of FDA records showed the drug had been associated with more deaths than any other monitored medication.
The genetic test is only for patients on warfarin. It is designed to identify common variants in CYP2C9, an enzyme that breaks down warfarin, and VKORC1, a clotting enzyme that is the target of warfarin. While it cannot improve the bleeding risk for patients taking Pradaxa, it can help medical professionals determine the best dosage of warfarin to reduce a patient’s risk of hemorrhaging.
Source: News Medical