Protamine Sulfate Mechanism of Action

    Mechanism of Action (API Function)

Protamine sulfate acts by electrostatic binding to heparin:

• Heparin is a strongly anionic glycosaminoglycan used as an anticoagulant.
• Protamine is a strongly cationic protein; when combined with heparin, they form a stable, inactive salt complex with no anticoagulant activity. 

This neutralization is rapid (typically within ~5 minutes after IV administration). 

Additionally:

• Unbound protamine itself can have a weak anticoagulant effect at high doses.
• Some interactions with clotting factors (e.g., factor Xa/antithrombin complexes) have been observed in experimental contexts