Effect of metiamide, a histamine H2 - receptor antagonist, on the development of gastric stress ulcers and acid secretion.

In normal and stressed rats with chronic gastric fistula small doses of metiamide (0.001-0.01 muM/kg) increased and doses of over 20 muM/kg decreased gastric acid secretion. In both these dose ranges of dosage metiamide suppressed the development of stress ulcers, most markedly in doses of 0.005 and 100 muM/kg. Intermediate doses had no such action. Only the anti-ulcer action of large doses of metiamide ran parallel to a reduction in acid secretion. Small doses of metiamide increased gastric secretion, but like larger doses, had a weak adrenergic action.