Low molecular weight heparins and their clinical applications.

Heparin is an anticoagulant medication that was discovered in 1917 and used in clinic since 1935. Low molecular weight heparins (LMWHs) represent a refined use of heparin as anticoagulant medications that were developed in 1980s. LMWHs are obtained by cleaving heparin with different chemical or enzymatic methods. Eight chemically distinct and officially approved LMWHs are Bemiparin, Certoparin, Dalteparin, Enoxaparin, Nadroparin, Parnaparin, Reviparin, and Tinzaparin. LMWHs are mainly used for preventing blood clots, for treating deep vein thrombosis and pulmonary embolism, and for treating myocardial infarction. LMWHs have advantages over heparin in that they can be used at home with good predictability, dose-dependent plasma levels, a long half-life, less bleeding for a given antithrombotic even, smaller risk of osteoporosis in long-term use, and smaller risk of heparin-induced thrombocytopenia and thrombosis, a potential side effect of heparin. However, heparin is reversible with protamine sulfate while LMWHs have no antidote. Moreover, LMWHs have less of an effect on inhibiting thrombin activity than heparin. Furthermore, patients with end-stage renal diseases have to use heparin because LMWHs are dependent on functioning kidney for their clearance but heparin is primarily cleared in the liver. We will review the recent progress made on the clinically approved and under clinical trialed LMWHs and their potential medical applications. In particular, we will provide an update on the chemical characteristics and clinical use of different branded LMWHs. In addition, the potential clinical applications of LMWHs in other therapeutic area will also be discussed.