Gastric antisecretory properties of SCH 32651

This report describes the gastric antisecretory properties of SCH 32651 (3-amino-2-methyl-8-phenylmethoxyimidazo[1,2-a] pyrazine HCl . 1/3 H2O). In the pyloric ligated rat, SCH 32651 inhibited gastric acid secretion; the oral ID50 (95% confidence limits) was 23.7 (13.8-39.2) mg/kg. In Heidenhain pouch dogs, SCH 32651 antagonized histamine-stimulated acid secretion with an ID50 of 1.44 (0.55-3.91) mg/kg p.o. SCH 32651 was also active against secretory responses to dimaprit, pentagastrin and feeding in dogs. In all test models SCH 32651 showed similar potency to cimetidine. Chronic administration of SCH 32651 or cimetidine caused slight tolerance and its antisecretory effect was readily reversible on cessation of dosing. The data indicate that SCH 32651 is an orally effective novel antisecretory drug.