Summary
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.
Keywords
LMW heparin - Venous thrombosis - Bleeding - Experimental Summary
