This invention relates to compounds of the formula (I): or a pharmaceutically acceptable salt thereof, wherein: R′, R2, R3, R4, R5, R6, R7, R8 A and B are each as described herein or a pharmaceutically acceptable salt, and compositions containing such compounds and the method of treatment and the use, comprising such compounds for the treatment of a condition mediated by acid pump antagonistic activity such as, but not limited to, as gastrointestinal disease, gastroesophageal disease, gastroesophageal reflux disease (GERD), peptic ulcer, gastric ulcer, duodenal ulcer, NSAID-induced ulcers, gastritis, infection of Helicobacter pylori, dyspepsia, functional dyspepsia, Zollinger-Ellison syndrome, non-crosive reflux disease (NERD), visceral pain, heartburn, nausea, esophagitis, dysphagia, hypersalivation, airway disorders or asthma.