Histamine H2 receptor (H2R) (H2R)

The Histamine H2 receptor (H2R) is a G protein-coupled receptor (GPCR) that serves as the primary mediator of histamine-stimulated gastric acid secretion (UniProt, P25021). Located on the basolateral membrane of gastric parietal cells, H2R activation triggers the Gs-adenylyl cyclase pathway, increasing intracellular cAMP and activating the H+/K+ ATPase proton pump (StatPearls, NBK532971). Beyond the stomach, H2 receptors are expressed in the heart, brain, and immune cells, where they influence cardiac chronotropy and inflammatory signaling (PubMed, 21251154). The term Pharmacokinetic interaction with ranitidine refers to the clinical phenomenon where ranitidine, an H2R antagonist, alters the absorption or excretion of other drugs (PubChem, CID 5035). These interactions occur either through the elevation of gastric pH, which affects drug solubility, or through the inhibition of renal transporters such as Organic Cation Transporter 2 (OCT2) (PubMed, 11566464). While ranitidine was widely used for peptic ulcers and GERD, many formulations were withdrawn globally due to concerns regarding N-nitrosodimethylamine (NDMA) contamination (FDA, 2020).

Other names

HRH2H2 receptorGastric receptor H2Histamine receptor H2

Competitive antagonism of the Histamine H2 receptor on gastric parietal cells, which inhibits the stimulation of adenylyl cyclase and reduces the production of gastric acid (StatPearls, NBK532971).