Prevention of subarachnoid hemorrhage-induced cerebral vasospasm by oral administration of endothelin receptor antagonists

✓ The purpose of this study was to investigate the effectiveness of oral treatment with the endothelin (ET)A/B receptor antagonist Ro 47-0203, 4-tert-butyl-N-[6-(hydroxy-ethoxy)-5-(2-methoxy-phenoxy)-2′-bipyrimidin-4-yl]-benzenesulfonamide (bosentan), and the ETA receptor antagonist 2-benzo[1,3]dioxol-5-yl-3-benzyl-4-(4-methoxy-phenyl)-4-oxobut-2-enoic acid monosodium salt (PD155080), in the prevention of subarachnoid hemorrhage (SAH)—induced delayed cerebral vasospasm. Double hemorrhage in the rabbit constricted the basilar artery to 34% of control as determined by angiography. Oral bosentan and PD155080 administration after the initial SAH decreased the magnitude of constriction to 9% and 16% of control, respectively. Plasma and cerebrospinal fluid bosentan levels and plasma PD155080 levels were consistent with concentrations reported to inhibit ET-1 constriction of blood vessels in vitro. These results support the use of oral administration of ETA/B and ETA receptor antagonists as potential specific treatment for vasospasm resulting from SAH in humans.