Effects of a new histamine H₂-receptor antagonist, ranitidine, on experimental acute gastric and duodenal ulcers

Abstract

Ranitidine at 100 to 200 mg/kg (i.d. or p.o.) potently inhibited the development of Shay ulcers, indomethacinor phenylbutazone-induced gastric ulcers and histamine-carbachol-induced duodenal ulcers in rats. Ranitidine at 100 mg/kg (p.o.) also inhibited the development of water-immersion stress-induced gastric ulcers in rats, histamine-induced gastric and duodenal ulcers in guinea pigs, even though the inhibition rate remained within 70%, At that time, the gastric acid output in guinea pigs was reduced with some doses of the drug. Cimetidine at 100 to 200 mg/kg (p.o.) also inhibited the development of indomethacin-, phenylbutazone-, and waterimmersion stress-induced gastric ulcers in rats and histamine-induced gastric and duodenal ulcers in guinea pigs. Shay ulcers and histamine-carbachol-induced duodenal ulcers in rats were not affected by cimetidine. Both ranitidine and cimetidine inhibited the gastric acid output in pylorus-ligated rats (7 hr) ; the maximal inhibition being 79.6% and 50.7% respectively. The mechanism by which ranitidine inhibits various experimental ulcers might be mainly the inhibition of gastric secretion. Gefarnate at 300 mg/kg (p.o.) significantly inhibited phenylbutazone-induced gastric ulcers in rats but had no effect on other ulcer models.