Effect of cilostazol, a new antithrombotic drug, on cerebral circulation

The effects on cerebral blood flow and the selectivity of the vasodilating action of cilostazol (6-[4-(1-cyclohexyl-1H-tetrazol-5-yl)butoxy]-3,4-dihydro-2(1H)-qui nolinone, OPC-13013), a new antithrombotic drug, were investigated. In anesthetized dogs, cilostazol increased the venous outflow from the superior sagittal sinus in doses of higher than 10 micrograms/kg i.v. In anesthetized cats, cilostazol was demonstrated by the hydrogen clearance method to cause a dose-dependent increase in blood flow in both the white matter and the grey matter in doses of higher than 10 micrograms/kg/min i.v. The effective dose of cilostazol when compared at ED25 values, which is the dose required to produce a 25% increase in blood flow, was almost equal to that of papaverine and more potent than those of bencyclane and pentoxifylline. Arterial blood gas analysis revealed no significant changes in pCO2, pO2 and pH by intravenous administration of cilostazol. In anesthetized dogs, after intra-arterial administration at a constant perfusion pressure, cilostazol increased the blood flow of the common carotid, internal carotid, vertebral, superior mesenteric and femoral arteries in a dose-dependent manner in doses higher than 1 microgram, and had almost no effect on renal blood flow. High selectivity for the vertebral and femoral arteries was observed.