[Anticoagulants in clinical practice]

Four classes of anticoagulants are now available: vitamin K antagonists, heparin, Orgaran and hirudin. For each of these classes the mechanism of the anticoagulant effect, the usual doses and biological monitoring are described. Each low molecular weight heparin must be considered as an original product. Orgaran and hirudin are new antithrombotic agents allowing to solve the dramatic problems raised by heparin-induced thrombocytopenia.