These are drugs that inhibit the production of acid in the stomach by blocking a key enzyme system, known as the PROTON PUMP, of the parietal cells of the stomach. The drugs include omeprazole, lansoprazole and pantoprazole, and they are the treatment of choice for oesophagitis (erosion and stricture – see under OESOPHAGUS, DISEASES OF); for the short-term treatment for gastric ulcer (see under STOMACH, DISEASES OF) and DUODENAL ULCER; and, in combination with ANTIBIOTICS, for the eradication of Helicobacter pylori.