The DDDs of nonfractionated heparin and antithrombin are based on prophylaxis of thrombosis and pulmonary emboli, and given in international units (U). The DDDs for the different low molecular weight heparins are assigned according to their recommended dose in prophylaxis of deep vein thrombosis in moderate risk patients. Since the anti Xa activity is a major determinant of the anticoagulant activity of low molecular weight heparins the DDDs are given in international units based on anti Xa activity.
The DDD for sulodexide is expressed in lipoprotein lipase releasing units (LSU).