A potent and selective EP4 receptor antagonist (Kis = 11.7, >10,000, and >10,000 nM for EP4, EP2, and EP3, respectively); selective for EP4, exhibiting 2-induced cAMP accumulation in HEK293 EBNA cells that stably express human EP4 receptors; reverses PGE2-induced vasorelaxation (Kb = 15.85 nM) in human middle cerebral and middle meningeal arterial rings; prevents PGE2-induced increases in carotid blood flow and decreases in carotid resistance in dogs (ID50 = 5 mg/kg)