Tagamet

Tagamet is the brand name for cimetidine, a histamine H2 receptor antagonist used to reduce gastric acid secretion. By blocking H2 receptors on gastric parietal cells, it decreases acid production, raising stomach pH and aiding the healing of acid-related conditions.

Medical uses of Tagamet include treatment and prevention of peptic ulcers (duodenal and gastric), erosive esophagitis due to gastroesophageal reflux disease, gastritis, and conditions characterized by excess stomach acid such as Zollinger-Ellison syndrome. It is available in oral tablets, liquid, and injectable forms. Dosing varies by condition and patient, with common regimens including 200–400 mg four times daily or 800 mg at night for ulcers; GERD regimens may be similar or involve 400 mg twice daily. Some formulations are available over the counter for heartburn.

Adverse effects are generally mild but can include headache, dizziness, and fatigue. Rare but notable effects include antiandrogenic changes such as gynecomastia and decreased libido in men, galactorrhea, and confusion in the elderly. Cimetidine can cause hepatotoxicity and hypersensitivity reactions in rare cases. It inhibits several cytochrome P450 enzymes, potentially raising levels of drugs such as warfarin, theophylline, phenytoin, and certain benzodiazepines, among others. Antacids may affect absorption if taken simultaneously, so dosing may require separation. Caution is advised in kidney or liver impairment and during pregnancy, where use should be guided by a clinician.

History and status: Tagamet was one of the first histamine H2 blockers introduced in the 1970s and greatly influenced the treatment of peptic ulcer disease and GERD. Today, cimetidine is less commonly used due to drug interaction concerns and the availability of newer therapies, including other H2 blockers and proton pump inhibitors.