Warfarin

Mechanism of Action

Warfarin is a vitamin K antagonist (VKA) that inhibits vitamin K epoxide reductase (VKORC1), preventing the recycling of vitamin K epoxide to its active hydroquinone form. Vitamin K is a required cofactor for gamma-carboxylation of clotting factors II, VII, IX, and X, as well as anticoagulant proteins C and S. By depleting active vitamin K, warfarin produces a state analogous to vitamin K deficiency, reducing functional clotting factor synthesis. The anticoagulant effect is monitored via INR (international normalized ratio). Warfarin has a narrow therapeutic window and extensive drug-drug interactions via CYP2C9 metabolism.

Evidence Level

Clinical Trial - Human

6 studies published