Mechanisms of action of low molecular weight heparins and heparinoids.

From the Hamilton Civic Hospitals Research Centre and McMaster University, Hamilton, Ont., Canada. Address reprint requests to Dr. Weitz at the Hamilton Civic Hospitals Research Centre, 711 Concession St., Hamilton, ON L8V 1C3, Canada. ©1997, Massachusetts Medical Society. FTER almost two decades of intensive research, low-molecular-weight heparins have established their niche as an important class of antithrombotic compounds. The demonstration that these compounds are safe and effective for the prevention and treatment of venous thromboembolism has led to the licensing of several of them in Europe and North America. In addition, danaparoid sodium, which is a mixture of dermatan sulfate, heparan sulfate, and chondroitin sulfate, is often used for the treatment of heparin-induced thrombocytopenia. 1 Low-molecular-weight heparins have replaced unfractionated heparin in many parts of Europe but are only now finding their place in North America. Their use is likely to increase, however, because two recent studies show that about half of all patients with venous thrombosis can be safely treated with low-molecular-weight heparins without hospital admission, 2,3 and heparin-induced thrombocytopenia, a dangerous complication of unfractionated-heparin therapy, occurs less frequently with low-molecularweight heparins. 4