- Last Update On : 2013-01-26
In August 2007, the Food and Drug Administration (FDA) introduced new labeling to the warfarin and Coumadin package insert to inform physicians that gene variations may influence how patients respond to warfarin therapy. However, FDA did not recommend or require that genotyping be performed before initiation of warfarin therapy. Since that time, many pundits have predicted that warfarin pharmacogenomics would become the first major success story for personalized medicine. It was reasonable to expect that more accurate, pharmacogenetic-based initial dosing of warfarin would reduce the risk of serious bleeding and thrombotic complications. However, to date, only 3 small prospective randomized control trials have compared pharmacogenetic-based initiation of warfarin to empiric dosing and none of these studies have convincingly demonstrated that pharmacogenetic-based dosing is more efficacious than empiric dosing. Because of this paucity of data, the Centers for Medicare and Medicaid Services has announced that it will not pay for warfarin pharmacogenetic tests.
Consistent calls for additional trials to evaluate the clinical utility of pharmacogenetic-based warfarin dosing have been heard by the National Heart Lung and Blood Institute. The COAG (Clarification of Optimal Anticoagulation through Genetics) trial which is funding a prospective multicenter randomized controlled study is scheduled to begin in 2009. However, sufficient outcomes data will probably not be available for several years..