A nurse is caring for a client who is experiencing warfarin toxicity. Which of the following medications should the nurse administer?

Warfarin is an anticoagulant that works by inhibiting vitamin K–dependent clotting factors (II, VII, IX, and X). When toxicity occurs, patients are at high risk for bleeding due to excessive anticoagulation. Management focuses on reversing the anticoagulant effect to restore normal clotting function. The specific antidote depends on the medication involved, and in warfarin toxicity, vitamin K is the primary reversal agent. Rationale: A. Acetylcysteine is the antidote for acetaminophen (paracetamol) toxicity, not warfarin overdose. It works by replenishing glutathione stores to prevent liver damage from toxic metabolites. It has no role in reversing anticoagulation or restoring clotting factor activity. B. Calcium gluconate is used to treat hypocalcemia and stabilize cardiac membranes in hyperkalemia. It does not reverse anticoagulation or affect vitamin K–dependent clotting pathways. Therefore, it is not indicated for warfarin toxicity management. C. Protamine sulfate is the antidote for heparin toxicity, not warfarin. It works by binding to heparin and neutralizing its anticoagulant effect. Since warfarin acts through a different mechanism (vitamin K inhibition), protamine is ineffective in this situation. D. Vitamin K is the specific antidote for warfarin toxicity because it promotes the synthesis of vitamin K–dependent clotting factors in the liver. Administering vitamin K helps reverse excessive anticoagulation and reduces the risk of bleeding. In severe cases, additional therapies such as fresh frozen plasma may be used, but vitamin K remains the primary treatment.