🏥 USMLE Exam Prep

Warfarin inhibits coagulation by:

A Directly inhibiting thrombin
B Blocking vitamin K epoxide reductase, preventing synthesis of factors II, VII, IX, and X
C Activating antithrombin III
D Inhibiting platelet aggregation

✓ Correct Answer: Option B

Warfarin: vitamin K antagonist → inhibits gamma-carboxylation of factors II, VII, IX, X and proteins C/S. Monitored by INR/PT. Onset delayed (factor half-lives). Bridge with heparin initially.

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