5-Aminobenzimidazole inhibits gastric acid secretion in Shay-rats.

Benzimidazole and some of its derivatives as 4-nitro and 5-nitro-benzimidazoles, 2-amino-, 4-amino- and 5-aminobenzimidazoles have been tested on gastric acid secretion in Shay-rats. Only 5-aminobenzimidazole decreased the gastric secretory process basal or stimulated by betazole. The antisecretory properties of 5-aminobenzimidazole seem to be linked to an anti H2-histamine activity, since this compound depresses the amplitude of contractions of guinea pig isolated auricle stimulated by betazole. The antisecretive activity appears to be associated to a definite distance between the amino group and the imidazolyl nitrogen, since it appears only when the amino function is located in position 5 of the benzimidazole structure.