[A simple test for the monitoring of plasma anti-XA activity of patients following subcutaneous administration of enoxaparin].

Since low molecular weight heparin is used for the prevention of thromboembolism, the coagulation laboratories are in need of a simple, reliable and practicable test for factor Xa inhibition in order to monitor the effect of low molecular heparin in plasma. Effects of subcutaneous administration of 20 mg or 40 mg enoxaparin were studied in blood samples drawn from 20 patients before and 1, 2, 3, 4, 6, 12 and 24 hours after injection. Thrombin time, aPTT, Heptest and the anti-Xa activity (amidolytic assay) were measured. Subcutaneous administration of 20 mg or 40 mg enoxaparin was followed by a barely significant (p less than 0.05) rise in aPTT (only at the higher dosage) and thrombin time four hours after injection. Heptest and amidolytic assay (S-2222) correlated well and significant (p less than 0.01) increases, with maximum values 4 hours after injection, were seen after administration of 20 mg as well as of 40 mg enoxaparin. Higher mean values were achieved after injection of 40 mg than 20 mg enoxaparin. We believe the Heptest to be a quick and easily performed test, giving results which agree well with those of the amidolytic anti-Xa activity reference method.