Spizofurone (also known as AG-629) is a spirobenzofuranone derivative patented by Japan's largest pharmaceutical company Takeda Chemical Industries, Ltd. as the anti-ulcer agent. In preclinical models Spizofurone dose-dependently increase in gastric mucosal blood flow in anesthetized dogs. The reduction in the gastric mucosal blood flow as induced by indomethacin was markedly improved by spizofurone. The topical action of spizofurone was confirmed in an in situ experiment using a stomach flap fixed to a lucite chamber. Spizofurone given orally or i.p. in a dose range of 25-200 mg/kg inhibited indomethacin-induced gastric antral ulcers in rats. Furthermore, spizofurone potentiated the inhibitory effect of prostaglandin E2 on indomethacin-induced gastric antral ulcers. The increase in alkaline secretion in bullfrog duodenal mucosa seen in the presence of spizofurone is mediated, at least in part, by stimulation of endogenous prostaglandins synthesis.