Which agent is used to reverse heparin anticoagulation?

• A. Protamine sulfate
• B. Vitamin K
• C. Warfarin
• D. Calcium gluconate

Answer: (A)

Reversing heparin’s effect is achieved with protamine sulfate. Heparin works by boosting antithrombin III, which blocks thrombin and factor Xa, preventing clot formation. Protamine sulfate is a positively charged protein that binds tightly to the negatively charged heparin, forming a stable complex that neutralizes heparin’s anticoagulant activity.

The reversal is usually dose-dependent on the amount of heparin given, with typical guidance around one milligram of protamine per about 100 units of unfractionated heparin. It’s most effective for unfractionated heparin; reversal of low-molecular-weight heparin is incomplete and may require different management.

Be mindful of potential reactions to protamine, including hypotension or an anaphylactoid reaction in some patients, so administer slowly and monitor closely. Vitamin K reverses warfarin, not heparin, and calcium gluconate does not reverse heparin’s effect.