[Pharmacologic and clinical principles for rational anti-thrombotic preventive treatment with low molecular weight heparin].

Heparin exerts its anticoagulant function by accelerating the inhibitory effect of antithrombin III. Low molecular weight heparin (LMWH), which is derived from unfractionated heparin (UFH), exhibits marked anti-Xa activity and minor thrombin inhibition. It has an elevated bioavailability and longer half-life as to the anti-Xa clearance when compared to UFH. Platelet, endothelial and fibrinolytic effects are also involved in antithrombotic action. Clinical trials have shown that LMWH compared to UFH is an equivalent and even advantageous method of antithrombotic prophylaxis in surgical patients and has also a minor risk of bleeding.