What is the antidote that reverses warfarin’s effects?

What is the antidote that reverses warfarin’s effects?

• A. Vitamin K
• B. Protamine sulfate
• C. Fresh frozen plasma
• D. Platelet transfusion

Answer: (A)

Warfarin blocks the vitamin K–dependent production of clotting factors II, VII, IX, and X, so reversing its effect means restoring that vitamin K cycle to resume making these factors. Vitamin K serves as the antidote by reactivating the liver's production of functional clotting factors, so the coagulation cascade can resume. In urgent cases, IV vitamin K is used for quicker reversal, often alongside fresh frozen plasma or prothrombin complex concentrates to supply clotting factors immediately while vitamin K takes effect. Protamine sulfate reverses heparin, not warfarin; fresh frozen plasma provides factors but does not address the underlying deficiency caused by warfarin; platelet transfusion targets platelets, not the clotting factor deficit.

Warfarin blocks the vitamin K–dependent production of clotting factors II, VII, IX, and X, so reversing its effect means restoring that vitamin K cycle to resume making these factors. Vitamin K serves as the antidote by reactivating the liver's production of functional clotting factors, so the coagulation cascade can resume. In urgent cases, IV vitamin K is used for quicker reversal, often alongside fresh frozen plasma or prothrombin complex concentrates to supply clotting factors immediately while vitamin K takes effect. Protamine sulfate reverses heparin, not warfarin; fresh frozen plasma provides factors but does not address the underlying deficiency caused by warfarin; platelet transfusion targets platelets, not the clotting factor deficit.