To discover a gastric antisecretory agent more potent than existing proton pump inhibitors, novel pyrrole derivatives were synthesized, and their H+, K+-ATPase inhibitory activities and inhibitory action on histamine-stimulated gastric acid secretion in rats were evaluated. Among the compounds synthesized, compound 17a exhibited selective and potent H+, K+- ATPase inhibitory activity through reversible and K+-competitive ionic binding; furthermore ...