ANTICOAGULANT AGENTS IN THE MANAGEMENT OF PULMONARY-EMBOLISM

The anticoagulant agents most commonly used in the prevention and trea tment of pulmonary embolism (PE) are unfractionated heparin, oral anti coagulants, and low molecular weight heparins (LMWHs). Unfractionated heparin at low fixed dose is the prophylactic regimen of choice for PE in patients undergoing general surgery or with serious medical diseas es (low to moderate risk patients). In high risk patients perioperativ e prophylaxis with LMWHs or oral anticoagulants should be adopted. The rapy of pulmonary embolism should start with an intravenous bolus dose of 5000 U heparin followed by an infusion of 1250 U/h. Then the dose should be adjusted to maintain the aPTTx2-2.5 pre-treatment value. Hep arin is continued for 7-10 days and is followed by oral anticoagulants for at least 3 months. Unfractionated heparin has some pharmacologica l limitations, mainly due to the aspecific binding to plasma proteins that limits its anticoagulant effect and causes the heparin resistance observed in some patients with PE and the inter-subject variability o f the anticoagulant effect. Other antithrombotic agents such as LMWHs and selective thrombin inhibitors (hirudin and its analogues) do not a specifically bind to plasma proteins. They have recently been used wit h promising results in the prevention and treatment of PE. Their defin itive value in this clinical setting will be defined by the ongoing cl inical trials. (C) 1998 Elsevier Science Ireland Ltd.