Soraprazan (BYK61359) is a reversible, and fast-acting inhibitor of gastric H⁺/K⁺ ATPase. In Vitro: Soraprazan (BYK61359) is a potent inhibitor of gastric H,K-ATPase, with an IC₅₀ 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 [¹⁴C]AP accumulation in isolated gastric glands with an IC₅₀ of 0.19 μM (0.09-0.40 μM geometric mean from n=6 with 95% confidence limits). In ion-leaky vesicles, soraprazan is a potent k-competitive inhibitor of the H,K-ATPase, with K_i of 6.4 nM. Soraprazan binds to the H,K-ATPase in ion-leaky vesicles with a K_d of 26.4 nM and a Bmax of 2.89 nmol/mg^[1].