Protamine sulfate is the antidote for overdose of which anticoagulant?

• A. Heparin
• B. Warfarin
• C. Enoxaparin
• D. Rivaroxaban

Answer: (A)

Protamine sulfate neutralizes unfractionated heparin. It’s a positively charged compound that binds the negatively charged heparin molecule, forming a stable complex that cancels heparin’s anticoagulant effect and allows normal clotting to resume. This makes it the standard reversal agent for heparin overdose.

Warfarin overdose is reversed with vitamin K and, if rapid reversal is needed, blood products or concentrates to replace clotting factors. Enoxaparin (a low-molecular-weight heparin) can be partially reversed by protamine, but not as completely as unfractionated heparin. Rivaroxaban requires different reversal strategies (such as andexanet alfa) rather than protamine.