The antithrombotic activity of BAY g 6575

The activity of 1-[2-(beta-naphthyloxy)ethyl]-3-methyl-2-pyrazolin-5-one (= BAY g 6575) was evaluated in models of experimental thrombosis caused by traumatically induced damage of vessel segments. After prophylactic administration of BAY g 6575 (0.3 mg/kg p.o.) to rats the thrombus formation was significantly reduced in the carotid artery as well as in the jugular vein. The thrombus formation in the femoral arteries of rabbits is inhibited at a minimal effective dose of 1 mg/kg p.o. The incidence of occlusive thrombi is not influenced. BAY g 6575 is 10 times more potent than acetylsalicylic acid (ASA). In the arterial system the thrombus formation is frequently completely abolished.