Hypercoagulability and the management of anticoagulant therapy in surgical patients: review and recommendations

Unfractionated Heparin, Low Molecular Weight Heparins, and Pentasaccharide: Basic Mechanism of Actions, Pharmacology, and Clinical Use

During the past decade, a large number of new anticoagulant and antithrombotic drugs have been developed. These agents represent a wide variety of substances that are derived using natural sources, biotechnology-based methods, and synthetic approaches. Because of the structural and molecular characteristics, these agents exhibit physicochemical and functional diversities. Thus, each of these classes of drugs controls thrombogenesis by way of distinct mechanisms. The main classes of these new drugs include peptides, peptidomimetics, heparinomimetics, and recombinant proteins. Despite these significant developments, heparin and heparin-derived drugs have continued to play a major role in the management of thrombotic and cardiovascular disorders.

Clinical aspects of heparin-induced thrombocytopenia and thrombosis and other side effects of heparin therapy

Heparin, first used to prevent the clotting of blood in vitro, has been clinically used to treat thrombosis for more than 50 years. Although several new anticoagulant drugs are in development, heparin remains the anticoagulant of choice to treat acute thrombotic episodes. The clinical effects of heparin are meritorious, but side effects do exist. Bleeding is the primary untoward effect of heparin. Major bleeding is of primary concern in patients receiving heparin therapy. However, additional important untoward effects of heparin therapy include heparin-induced thrombocytopenia, heparin-associated osteoporosis, eosinophilia, skin reactions, allergic reactions other than thrombocytopenia, alopecia, transaminasemia, hyperkalemia, hypoaldosteronism, and priapism. These side effects are relatively rare in a given individual, but given the extremely widespread use of heparin, some are quite common, particularly HITT and osteoporosis. Although reasonable incidences of many of these side effects can be "softly" deduced from current reports dealing with unfractionated heparin, at present the incidences of these side effects with newer low molecular weight heparins appear to be much less common. However, only longer experience will more clearly define the incidence of each side effect with low molecular weight preparations.