Antithrombotic potency of
SDZ 217-766, a potent inhibitor of
thrombin and other
trypsin-like
serine proteases, was studied in comparison with
heparin in rat models of
thrombin induced lung platelet accumulation, of
thrombosis in arterio-venous shunt, and of
venous thrombosis induced by
tissue factor.
Thrombin-induced platelet accumulation in the lung was inhibited dose-dependently by
SDZ 217-766 following intravenous (i.v.) administration of 0.03 mg/kg to 0.3 mg/kg as well as by intraduodenal (i.d.) administration of 3 mg/kg and 10 mg/kg. Comparable inhibitory effects were observed with
heparin at 30 IU/kg and 100 IU/kg. In the rat arterio-venous shunt, following i.v. administration of
SDZ 217-766,
thrombus formation was inhibited by 40% at 0.1 mg/kg, by 60% at 0.3 mg/kg and was abolished at 1.0 mg/kg whilst APTT was prolonged 1.1 fold over the control value at 0.1 mg/kg and 2.7 fold at 1.0 mg/kg. Similar inhibitory effects were observed following i.d. administration of 10 and 30 mg/kg with only marginal (1.2 to 1.8 fold) APTT elevation. In the same model,
heparin administered either i.v., 30-300 IU/kg, or subcutaneously, 100 and 300 IU/kg, inhibited
thrombus formation dose dependently but in contrast to
SDZ 217-766, the inhibitory effect was paralleled by 5-to > 10 fold APTT elevation over baseline. In the
venous thrombosis model,
SDZ 217-766 infused
at 10 micrograms/kg/min and 20 micrograms/kg/min, reduced
thrombus formation by 35% and 70%, respectively. In comparison,
thrombus formation was decreased by 22% when
heparin was infused at 1 IU/kg/min, and abolished at 3 IU/kg/min.(ABSTRACT TRUNCATED AT 250 WORDS)