Soraprazan (BYK61359) is a selective, reversible K-competitive inhibitor of the H,K-ATPase ( K i =6.4 nM), with an IC 50 of 0.19 μM in gastric glands. Soraprazan binds to the H,K-ATPase with a Kd of 28.27 nM. Soraprazan shows immediate inhibition of acid secretion and is more than 2000-fold selective for H,K-ATPase over Na,K- and Ca-ATPases. In Vitro Soraprazan (BYK61359) is a potent inhibitor of gastric H,K-ATPase, with an IC 50 of 0.1 μM when measured in ion-leaky vesicles in the presence of 1 mM potassium. Soraprazan (BYK61359) also effectively inhibits dibutyryl cAMP-stimulated [ 14 C]AP accumulation in isolated gastric glands with an IC 50 of 0.19 μM (0.09-0.40 μM geometric mean from n=6 with 95% confidence limits). MCE has not independently confirmed the accuracy of these methods. They are for reference only. In Vivo Soraprazan (1-27 μmol/kg; p.o.) shows rapid and consistent inhibition of acid secretion in dog . MCE has not independently confirmed the accuracy of these methods. They are for reference only. Form:Solid