Cimetidiinin

Cimetidiinin is the term used in some languages for cimetidine, a histamine H2 receptor antagonist used to reduce gastric acid production. Developed in the 1970s and marketed as Tagamet, it was one of the first drugs in its class and helped transform the treatment of peptic ulcer disease and gastroesophageal reflux disease.

Mechanism and effects: Cimetidiinin works by competitively inhibiting histamine at H2 receptors on gastric parietal cells. This decreases both nocturnal and meal-stimulated acid secretion, leading to higher gastric pH and relief of ulcer and reflux symptoms. It does not inhibit acid production at all times but lowers it substantially during stimulation by gastrin and acetylcholine.

Indications: It has been used for the treatment and prevention of duodenal and gastric ulcers, GERD, dyspepsia, and erosive esophagitis. It has also been employed in certain eradication regimens for Helicobacter pylori in older protocols, though modern guidelines favor other regimens or proton pump inhibitors.

Pharmacokinetics: Cimetidiinin is administered orally or by intravenous injection. Oral bioavailability is about 60–70%, with peak levels in 1–3 hours. It is partly metabolized in the liver and largely excreted by the kidneys. The elimination half-life is about 2 hours in adults with normal renal function, and increases with renal impairment.

Safety and interactions: Common adverse effects include headache and dizziness; rare CNS effects such as confusion in elderly or renally impaired patients. Long-term high-dose use can cause antiandrogenic effects like gynecomastia. Cimetidiinin can inhibit several cytochrome P450 enzymes, leading to interactions with drugs such as warfarin, phenytoin, theophylline, lidocaine, and diazepam.

Status: Use has declined with proton pump inhibitors, but it remains available for specific indications or patient contexts where alternatives are not suitable.