For the treatment of disorders of the upper gastro-intestinal region that are due to an excess of hydrochloric acid in the gastric juice, i.e. duodenal ulcers, benign gastric ulcers. Also for prophylaxis of recurrent gastric and duodenal ulcers (en)
The H2 antagonists are competitive inhibitors of histamine at the parietal cell H2 receptor. They suppress the normal secretion of acid by parietal cells and the meal-stimulated secretion of acid. They accomplish this by two mechanisms: histamine released by ECL cells in the stomach is blocked from binding on parietal cell H2 receptors which stimulate acid secretion, and other substances that promote acid secretion (such as gastrin and acetylcholine) have a reduced effect on parietal cells when the H2 receptors are blocked. (en)