Pharma & Specialty Chemical Standards

Cimetidine (IUPAC: 4-amino-5-(2-thiazolyl)-2-imidazolidinone; molecular formula C8H13N5S, molecular weight 211.29 g/mol) is a thiazole-containing imidazolidinone derivative. Its structure features a fused thiazole and imidazolidinone ring system with an amino substituent. A classic H2-receptor antagonist, it inhibits histamine-mediated gastric acid secretion by competitively blocking H2 receptors on parietal cells. Therapeutically used for peptic ulcers and gastroesophageal reflux disease (GERD). It exhibits weak basicity (pKa ~6.8), is lipophilic, and crosses the blood-brain barrier. Metabolized in the liver via N-demethylation and thiazole ring oxidation.