ラニチジン

用途ラニチジン（英: Ranitidine、開発コードAH19065）は、ヒスタミンH2受容体拮抗薬の一つである。壁細胞のH2受容体を遮断することにより胃酸分泌を抑制するため、胃酸分泌抑制薬として使用される。商品名ザンタック。消化性潰瘍、胃食道逆流症、Zollinger–Ellison症候群（英語版）の治療に使用される他、蕁麻疹の治療で有効であるとの報告がある。

説明Ranitidine, a H2-receptor agonist, caused contact dermatitis within the pharmaceutical industry.

来歴Ranitidine was first prepared in England as AH19065 by John Bradshaw in the summer of 1977 in the Ware research laboratories of Allen and Hanburys, part of the former Glaxo organisation.Glaxo refined the model further, by replacing the imidazole ring of cimetidine with a furan ring with a nitrogen-containing substituent, and in doing so developed ranitidine. Ranitidine was found to have a far-improved tolerability profile (i.e. fewer adverse drug reactions), longer-lasting action, and 10 times the activity of cimetidine. Ranitidine was introduced in 1981, and was the world's biggest-selling prescription drug by 1987. Subsequently, it was largely superseded by the more effective proton-pump inhibitor (PPI) class of drugs, with omeprazole becoming the biggest-selling drug for many years.In September 2019, the probable carcinogen N-nitrosodimethylamine (NDMA) was discovered in ranitidine products from a number of manufacturers, resulting in recalls; in April 2020, it was withdrawn from the United States market and suspended in Europe and Australia. In 2024, ranitidine was re-approved for sale in Australia after the local sponsor of Zantac changed suppliers and tablet formulation. The new formulation was demonstrated to be stable throughout its shelf life and that nitrosamines are controlled within internationally established acceptable intake limits applied to the maximum daily dose.

使用Ranitidine (cas# 66357-35-5) was used as a standard for testing the therapeutic effect of brown propolis extract against aspirin and ethanol- induced gastric ulcers.

一般的な説明Ranitidine, N-[2-[[[5-(dimethylamino)methyl]-2-furanyl]methyl]thiol] ethyl]-N'-methyl-2-nitro-l,1-ethenediamine (Zantac), is a white solid, which inits hydrochloride salt form is highly soluble in water. It is anaminoalkyl furan derivative with pKa values of 2.7 (sidechain) and 8.2 (dimethylamino). Ranitidine is more potentthan cimetidine, but less potent than famotidine. Likeother H2-antagonists, it does not appear to bind to otherreceptors.Bioavailability of an oral dose of ranitidine is about 50%and is not significantly affected by the presence of food.Some antacids may reduce ranitidine absorption and shouldnot be taken within 1 hour of administration of this drug. Theplasma half-life of the drug is 2 to 3 hours, and it is excretedalong with its metabolites in the urine. Three metabolites, ranitidineN-oxide, ranitidine S-oxide, and desmethyl ranitidine,have been identified. Ranitidine is only a weak inhibitor ofthe hepatic cytochrome isozymes, and recommended doses ofthe drug do not appear to inhibit the metabolism of otherdrugs. However, there have been isolated reports of drug interactions(warfarin, triazolam) that suggest that ranitidinemay affect the bioavailability of certain drugs by someunidentified mechanism, perhaps by pH-dependent effect onabsorption or a change in volume of distribution.In addition to being available in various dosage forms asthe hydrochloride salt, ranitidine is also available as a bismuthcitrate salt for use with the macrolide antibiotic clarithromycinin treating patients with an active duodenalulcer associated with H. pylori infection. Eradication of H.pylori reduces the risk of duodenal ulcer recurrence.