Volume 1, Issue 2, 02/04/2009
How is warfarin (Coumadin®, Jantoven®) use in clinical practice influenced by known genetic polymorphisms to CYP450 2C9 and when is testing needed, if at all?
Warfarin (Coumadin®, Jantoven®) is the most prescribed oral anticoagulant for the prevention and treatment of thromboembolic events in both North America and Europe.(1) Despite its common use, it can be one of the more difficult and time consuming medications for clinicians to manage. In most situations, the desired International Normalized Ratio (INR) goal ranges from 2 to 3. It is within this range that benefits of therapy outweigh the risk for bleeding in most patients. Factors such as changes in diet, compliance, other medications and comorbidities provide only some of the explanations for the variation in INR that sometimes result in complicated, patient specific dosing regimens.(1) Two non-changing factors that primarily impact the initial titration phase of warfarin, are genetic polymorphisms of cytochrome P450 (CYP) 2C9 (involved in the metabolism of warfarin) and vitamin K 2,3-epoxide reductase complex 1 (VKORC1) gene expression (involved in the "activation" of vitamin K dependent clotting factors - covered in another newsletter issue).(1,2)......To read the full answer please LOGIN or SUBSCRIBE NOW.
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