Tenatoprazole inhibits basal gastric acid secretion in pylorus-ligated rats in a dose-dependent manner (ED₅₀=4.2 mg/kg p.o.). In gastric fistula rats, tenatoprazole (2.5 and 5 mg/kg i.d.) also inhibits gastric acid secretion stimulated by histamine, carbachol or tetragastrin. Furthermore, tenatoprazole prevents the formation of water-immersion restraint stress-, pylorus ligation- and indomethacin-induced gastric lesions, and mepirizole-induced duodenal ulcer in rats^[1]. Maximum binding of tenatoprazole is 2.9 nmol/mg of the enzyme at 2 h after IV administration. The binding sites of tenatoprazole are in the TM5/6 region at Cys813 and Cys822. The bioavailability of tenatoprazole is two-fold greater in the (S)-tenatoprazole sodium salt hydrate form as compared to the free form in dogs^[2].