What is the mechanism of action of heparin?

What is the mechanism of action of heparin?

• A. Binds to antithrombin to inactivate thrombin and disrupt clotting cascade.
• B. Directly inhibits platelet aggregation.
• C. Increases fibrinolysis.
• D. Inhibits vitamin K.

Answer: (A)

Heparin works by binding to antithrombin III and greatly increasing its ability to inhibit key enzymes in the clotting cascade, especially thrombin (factor IIa) and factor Xa. This prevents fibrin formation and stops further clot development. It’s an anticoagulant effect, not a so-called “plaque breaker” or clot breaker. It doesn’t directly inhibit platelet aggregation (that’s more typical of antiplatelet drugs), it doesn’t by itself promote fibrinolysis (that would be agents like tPA), and it doesn’t affect vitamin K (that’s the mechanism of warfarin). In unfractionated heparin, clinicians monitor with aPTT and reverse with protamine sulfate if needed.

Heparin works by binding to antithrombin III and greatly increasing its ability to inhibit key enzymes in the clotting cascade, especially thrombin (factor IIa) and factor Xa. This prevents fibrin formation and stops further clot development. It’s an anticoagulant effect, not a so-called “plaque breaker” or clot breaker. It doesn’t directly inhibit platelet aggregation (that’s more typical of antiplatelet drugs), it doesn’t by itself promote fibrinolysis (that would be agents like tPA), and it doesn’t affect vitamin K (that’s the mechanism of warfarin). In unfractionated heparin, clinicians monitor with aPTT and reverse with protamine sulfate if needed.