Antithrombotic effect of OP/LMWH by subcutaneous route in rats

The aim of this study was to compare the antithrombotic and haemorrhagic effects of unfractionated heparin and OP/LMWH, a new low molecular weight heparin fragment, after subcutaneous administration in rats. Both heparins showed antithrombotic efficacy in a model of acute venous thrombosis even at 1 mg/kg; furthermore OP/LMWH presented a significantly higher activity in subacute venous thrombosis of the rat. At all the dosages tested OP/LMWH showed a significantly shorter bleeding time in the rat by the "transection" method, compared with unfractionated heparin. This study suggests the possibility of dissociating the antithrombotic and haemorrhagic effects of some heparin fractions.