The inhibition of histamine formation in vivo

Histamine formation was measured by the [¹⁴C]histamine content of the stomach following injection of [¹⁴C]histidine into rats. Carbonyl reagents (e.g. oxyamines) which inactivate pyridoxal phosphate, the co-enzyme of histidine decarboxylase, were the most effective inhibitors of histamine formation in vivo. Although the oximes prepared from imidazol-4(5)-ylmethoxyamine and pyridoxal or pyridoxal phosphate cannot inactivate the co-enzyme, they proved sufficiently potent to merit further study as inhibitors of histamine formation in vivo.