A 4-(3-methoxypropoxy)-3-methylpyridinyl derivative of timoprazole that is used in the therapy of STOMACH ULCERS and ZOLLINGER-ELLISON SYNDROME. The drug inhibits H(+)-K(+)-EXCHANGING ATPASE which is found in GASTRIC PARIETAL CELLS.

An alpha-pyridylmethylsulfinyl benzimidazole and a selective and irreversible proton pump inhibitor with antisecretory property. Rabeprazole enters the parietal cell and accumulates in the acidic secretory canaliculi where the agent is activated by a proton-catalyzed process that results in the formation of a thiophilic sulfonamide or sulfenic acid. The activated rabeprazole forms covalent bonds with the sulfhydryl amino acids cysteine on the extracellular domain of the proton pump (H+/K+ ATPase) at the secretory surface, thereby inhibiting the transport of hydrogen ions, via exchange with potassium ions, into the gastric lumen. Binding to cysteine 813, in particular, is essential for inhibition of gastric acid production.