DA 4626 is H2-receptor antagonism. The compounds which were investigated in a wider concentration range, i.e. DA 4360, DA 4577, and DA 4626, behaved as simple competitive antagonists, yielding apparent KB values comparable with those estimated in conventional H2-receptor assays. These results provide further evidence for the highly selective H2-receptor antagonism of these new molecules, and confirm the suitability of the histamine-stimulated adenylate cyclase assay in guinea-pig gastric cells as a functionally reduced system for the study of H2 antagonists.
