Gastric mucosal bleeding after unfractionated and low molecular weight heparin in rats

The bleeding from an induced gastric mucosal lesion was monitored after intravenous administration of unfractionated heparin and enoxaparin, a low molecular weight heparin. The gastric mucosa was exposed in a chamber, which was superfused with saline and emptied at 1-min intervals for quantitation of bleeding. Both heparins prolonged the bleeding time and increased the blood loss dose-dependently. Five to ten times higher doses of enoxaparin (in terms of anti-Xa units) were required to achieve similar prolongation of the bleeding times as with unfractionated heparin. The results indicate a more favourable antihaemostatic effect of enoxaparin than of unfractionated heparin.