A comparison of the antithrombotic and haemorrhagic effects of a low molecular weight heparin (LHN-1) and conventional heparin.
The antithrombotic effects after intravenous administration of a low molecular weight heparin (LHN-1) and conventional heparin were compared in a rabbit model of experimental thrombosis, where thrombus formation was induced by a combination of endothelial damage and stasis. Both compounds were able to prevent thrombosis completely. However, LHN-1 was significantly less potent than conventional heparin, the ratio between doses with the same antithrombotic effect being 2.4:1 on a weight basis. Bleeding times after administration of LHN-1 and conventional heparin were determined by tail transsection in anaesthetized rats and by template bleeding in the ear of conscious pigs. Given intravenously at a dose ratio of 2.4:1 (w/w), LHN-1 affected APTT less than conventional heparin, whereas the effects on haemostasis were not significantly different. In conclusion, it was found that after intravenous administration LHN-1 prevented experimental thrombosis as effectively as conventional heparin. However, the correlation between antithrombotic and haemorrhagic effects of LHN-1 was the same as that of conventional heparin. The corresponding relation in man remains to be determined.
D000818:Animals; D001760:Bleeding Time; D005260:Female; D006470:Hemorrhage / Q000139:chemically induced; D006487:Hemostasis / Q000187:drug effects*; D006493:Heparin / Q000494:pharmacology*; D008297:Male; D010314:Partial Thromboplastin Time; D011817:Rabbits; D051381:Rats; D011919:Rats, Inbred Strains; D013552:Swine; D013927:Thrombosis / Q000188:drug therapy*
D006493:Heparin