What is the mode of action of warfarin?: (A) Factor Xa inhibitor, (B) Vitamin K antagonist, (C) Activates antithrombin III, (D) Activates factor IX
Answer is B. Ref: KD Tripathi, 7th ed. pg. 620, 621* Warfarin and its congeners act as anticoagulants only in vivo (body), NOT in vitro (lab).* It acts by inhibiting Vitamin K. Due to overdose, hematuria is the first manifestation noted.* Dose monitoring is done by INR* Antidote of warfarin overdose: Vitamin K