Ranitidine Hydrochloride (AH19065) is a member of the class of histamine H2-receptor antagonists with antacid activity. Ranitidine is a competitive and reversible inhibitor of the action of histamine, released by enterochromaffin-like (ECL) cells, at the histamine H2-receptors on parietal cells in the stomach, thereby inhibiting the normal and meal-stimulated secretion of stomach acid. In addition, other substances that promote acid secretion have a reduced effect on parietal cells when the H2 receptors are blocked.

Ranitidine bismuth citrate, an orally administered Histamine H2-receptor antagonist, demonstrates a potent inhibitory concentration (IC 50) of 3.3 μM and exhibits high selectivity towards SARS-CoV-2-infected cells. It is widely utilized as an anti-Helicobacter pylori agent, exhibiting a minimum inhibitory concentration (MIC 90) value of 16 ng/L.

Ranitidine (HSDB 3925) is a non-imidazole blocker of those histamine receptors that mediate gastric secretion (H2 receptors). It is used to treat gastrointestinal ulcers.