Effects of Heparin on the normal clotting mechanisms

Pharmocodynamics

Fibrin formation inhibition

• induces anticoagulation by primarily potentiating the activity of AT-III
• to a lesser degree induces anticoagulation by binding to cofactor II [II inactivates thrombin independent of AT-III]
• attaches to AT-III, thereby altering AT-III, thereby rendering it more attractive to thrombin
• increases the thrombin inhibitory potency of AT-III by >1000X
• Thrombin enzymatically converts fibrinogen to fibrin + activates cofactors V & VIII
• AT-III inhibits thrombin + IXa, XIa & XIIa

K. C. Potger
Copyright © 2001