The Future of Anticoagulation

ABSTRACT

The conventional management of thrombotic disorders is based on the use of heparin, oral anticoagulants, and aspirin. The development of low molecular weight heparins and the synthesis of heparinomimetics such as the chemically synthesized pentasaccharide represent a refined use of heparin. Aspirin still remains the lead drug in the management of thrombotic and cardiovascular disorders. The newer antiplatelet drugs such as the adenosine diphosphate receptor inhibitors, glycoprotein IIb/IIIa (GPIIb/IIIa) inhibitors and other specific inhibitors have limited effects and have been tested in patients who have already been treated with aspirin. The oral anticoagulants such as warfarin provide a convenient and affordable approach in the long-term outpatient management of thrombotic disorders. The optimized use of these drugs still remains the approach of choice to manage thrombotic disorders. The new anticoagulant drugs target specific sites in the hemostatic network. There is a major thrust on the development of orally bioavailable anticoagulant drugs to replace oral anticoagulants. Heparin and low molecular weight heparins have been considered with various chemical enhancers for absorption. Both the factor Xa and antithrombin agents have been developed for oral use and some of these agents are in clinical development. Besides the limited bioavailability, the therapeutic indices of some of these drugs have been rather disappointing. Factor Xa inhibitors such as the pentasaccharides have undergone aggressive clinical development. The newer antiplatelet drugs have added a new dimension in the management of thrombotic disorders. The newer drugs are attractive for several reasons; however, none of these are expected to completely replace the conventional drugs in polytherapeutic approaches. It is conceivable that some of the newer drugs in combined modalities may mimic the broad therapeutic spectrum of heparins and warfarin. However, clinical validation is required for the therapeutic interchange for specific indications.

KEYWORDS

Anticoagulation - deep vein thrombosis - anti-Xa agents - antithrombin agents - antiplatelet agents - combination therapy

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