Low Molecular Weight Heparin

Low Molecular Weight Heparin

In medicine, low-molecular-weight heparin (LMWH) is a class of medication used as an anticoagulant in diseases that feature thrombosis, as well as for prophylaxis in situations that lead to a high risk of thrombosis. Thrombosis, or thrombotic disease, is the formation of a clot within a blood vessel which interferes with the blood supply to tissues and causes problems such as deep vein thrombosis, pulmonary embolism when it is located in the veins, or heart attacks and strokes when located in the arteries.

Heparin is a naturally occurring polysaccharide that inhibits coagulation, the process that forms a thrombosis. Natural heparin consists of molecular chains of varying lengths, or molecular weights. Chains of varying molecular weights, from 5000 to over 40,000 Daltons, make up polydisperse pharmaceutical-grade heparin. LMWHs, in contrast, consist of only short chains of polysaccharide. LMWHs are defined as heparin salts having an average molecular weight of less than 8000 Da and for which at least 60% of all chains have a molecular weight less than 8000 Da. These are obtained by various methods of fractionation or depolymerisation of polymeric heparin.

Heparin derived from natural sources, mainly porcine intestine or bovine lung, can be administered therapeutically to prevent thrombosis. However, the effects of natural, or unfractionated heparin are more unpredictable than LMWH.