Betazole is a histamine H2 receptor agonist. Also known as Ametazole. Betazole hydrochloride is known as gastramine and histalog. It has been used as a gastric stimulant to test for maximal production of gastric secretion activity. The test can be used in diagnosis of diseases such as Zollinger-Ellison syndrome where there is excess acid production, in this case driven by over production of gastrin.