Warfarin exerts its anticoagulant effect through inhibition of which enzyme?

• A Thrombin (factor IIa)
• B Adenosine diphosphate receptor on platelets
• C Factor Xa directly
• D Vitamin K epoxide reductase ✓

Explanation

Warfarin blocks vitamin K epoxide reductase (VKORC1), preventing regeneration of reduced vitamin K needed for gamma-carboxylation of glutamate residues on factors II, VII, IX and X and on proteins C and S. Un-carboxylated factors cannot bind calcium and phospholipid surfaces, so coagulation fails. Direct thrombin and Xa inhibition describes dabigatran and rivaroxaban respectively, while ADP receptor blockade describes clopidogrel.

Reference: Katzung's Basic and Clinical Pharmacology, 16th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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