What is the antidote for heparin?

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

Answer: (A)

Reversing heparin exposure relies on protamine sulfate, which binds heparin to form a stable complex and neutralize its anticoagulant effect. Protamine is a positively charged protein that directly neutralizes unfractionated heparin, restoring normal coagulation. In practice, dosing is tied to how much heparin was given and how recently; a common approach is about 1 mg of protamine for every 100 units of unfractionated heparin administered within the last 2–3 hours, with adjustments based on timing and bleeding status. Be mindful of potential adverse reactions, including hypotension and rare anaphylaxis. For low-molecular-weight heparin, protamine reverses only part of the effect, so reversal is incomplete. Other options: vitamin K reverses warfarin, desmopressin addresses certain platelet function disorders, and fresh frozen plasma provides clotting factors but is not the targeted antidote for heparin.