E-3710 (Z-215) is a new proton pump inhibitor (PPI). E-3710 irreversibly inhibited H(+),K(+)-ATPase activity in pig gastric vesicles with an acidic internal environment. E-3710 is a long-acting inhibitor of gastric acid secretion and a promising novel therapy for acid-related diseases, such as gastroesophageal reflux disease. E-3710 is metabolized through oxidation, reduction and conjugation. Unchanged E-3710 was excreted in urine at trace levels but was not detected in faces. The major isozyme contributing to the oxidation of Z-215, including the formation of Z-215 sulphone, was CYP3A4. It is useful for treating gastroesophageal reflux disease in all CYP2C19 genotypes. E-3710 is in phase II clinical trial for the treatment of erosive esophagitis and gastro-esophageal reflux.