[Effect of low-molecular heparin on blood coagulation]

The coagulation-inhibiting effect of subcutaneously administered commercial and a low-molecular heparin was compared in healthy volunteers. Global clotting activity, measured as activated partial thromboplastin time as well as thrombin activity were inhibited almost equally by commercial and low-molecular heparin. Low-molecular heparin caused a ten-fold stronger inhibition of factor Xa. The effect on factor Xa increased nearly logarithmically with the injected dose. Half-life of heparin measured in terms of the inhibition of factor Xa was 5.5 hours for the low-molecular and 3.5 hours for the commercial preparation. These results indicate that low-molecular heparin has a high specificity in the inhibition of factor Xa. A lower dose of low-molecular heparin, administered once daily, may have an anti-thrombotic effect while reducing the risk of bleeding.