Low molecular weight heparin mainly inhibits which factor?
INDIRECT THROMBIN INHIBITORS This group includes unfractionated heparin, low molecular weight heparin and fondaparinux Acts by activating antithrombin III (AT III) in plasma. Normally AT III inactivates factor Xa and IIa (thrombin) but the reaction is very slow. Heparin accelerates this inactivation process by binding to AT III and inducing the conformational change in it to expose the binding sites. Only conformational change is required for inactivation of factor Xa whereas inactivation of thrombin is also dependent on formation of scaffolding by heparin Unfractionated heparin Provides this scaffolding and thus inhibits both factor IIa and Xa Anticoagulant of choice for cardiopulmonary bypass LMW heparins and fondaparinux only cause conformational change in AT III and thus inhibit mainly factor Xa.
Factor IIIa
Factor VIIIa
Factor Xa
Factor XIIa
Hematology