Osutidine (T-593) is a H2 receptor antagonist which was undergoing development by Toyama Chemical for the treatment of peptic/gastric and duodenal ulcers. It is a beta-hydroxyphenethylamine derivative with both antisecretory and cytoprotective properties. Osutidine inhibited the histamine-induced cAMP generation in a concentration-dependent manner. Osutidine suppressed the maximal response of the histamine-induced positive chronotropic response, indicating that the compound is unsurmountable H2-antagonists. The metabolism of Osutidine in humans may not differ from that of rodents and dogs. No clinically relevant accumulation occurred following repeated dosage. In the single oral and subcutaneous dose toxicity studies in rats, there were no dead animals. The oral LD50 value was greater than 5 g/kg for both sexes, and there was no abnormality in general signs. An oral formulation of the drug was in phase III clinical trials in Japan, however Toyama has dropped it from clinical development.