Effects of NC-1300 and its degradation products on gastric secretion and HCl.ethanol-induced gastric lesions in rats.

The proton pump inhibitor NC-1300 has antisecretory and cytoprotective activities in rats. The compound is labile at an acidic pH and degrades into various products. We attempted to identify these products after treatment at different pHs in vitro using HPLC. We also examined whether (A) NC-1300 treated at acidic pHs loses its efficacy on gastric secretion and gastric lesions and (B) whether the degradation products of NC-1300 have pharmacological effects in rats. The acidic degradation products proved to be mainly NC-1300-sulfide and partly o-dimethylaminobenzylalcohol (o-DMABA) and benzimidazole (BI). NC-1300, pretreated at pH 1.0, 1.25 or 1.5 for 30 min and given p.o. at 30 mg/kg, significantly inhibited gastric acid secretion in pylorus ligated rats and prevented development of HCl X ethanol-induced gastric mucosal lesions. The degree of antisecretory and cytoprotective activities by NC-1300 treated at pH 1.5 was almost the same as that obtained by NC-1300 treated at pH 7.0. NC-1300-sulfide or mixtures of degradation products, with or without unchanged NC-1300, also significantly inhibited the gastric acid secretion and lesion formation. We conclude that while NC-1300 degrades at low pHs, the compound treated at such a low pH exerts pharmacological effects presumably by the unchanged form of NC-1300 and/or its degradation products.