Ilaprazole (IY-81149) sodium hydrate is an orally active proton pump inhibitor. Ilaprazole sodium hydrate irreversibly inhibits H + /K + -ATPase in a dose-dependent manner with an IC 50 of 6 μM in rabbit parietal cell preparation. Ilaprazole sodium hydrate is used for the research of gastric ulcers. Ilaprazole sodium hydrate is also a potent TOPK (T-lymphokine-activated killer cell-originated protein kinase) inhibitor.