Ranitidine

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Ranitidine
Systematic (IUPAC) name
(E)-N-(2-((5-((dimethylaminomethyl) furan-2-yl)methylthio)ethyl)- N'-methyl-2-nitroethene-1,1-diamine
Identifiers
CAS number	66357-35-5
ATC code	A02BA02
PubChem	3001055
DrugBank	APRD00254
Chemical data
Formula	C₁₃H₂₂N₄O₃S
Mol. mass	314.4 g/mol
Pharmacokinetic data
Bioavailability	39 to 88%
Metabolism	Hepatic
Half life	2–3 hours
Excretion	30–70% Renal
Therapeutic considerations
Licence data	US
Pregnancy cat.	B1(AU)
Legal status	Pharmacy Only (S2)(AU) OTC(US) P/POM (UK)
Routes	Oral, IV

Ranitidine (INN) (IPA: [rəˈnɪ tədin]) is a histamine H₂-receptor antagonist that inhibits stomach acid production, and commonly used in the treatment of peptic ulcer disease (PUD) and gastroesophageal reflux disease (GERD). It is currently marketed over the counter under the trade name Zantac by GlaxoSmithKline and by many other companies under various other names.

[edit] Clinical use

Main article: H2-receptor antagonist

Certain preparations of ranitidine are available over the counter (OTC) in various countries. In the United States, 75 mg and 150 mg tablets are available OTC. In Australia, small packs of 150 mg and 300 mg tablets are Schedule 2 Pharmacy Medicines. Larger doses and pack sizes still require a prescription.

Outside of the United States, ranitidine is combined with bismuth (which acts as a mild antibiotic) as a citrate salt (ranitidine bismuth citrate, Tritec®), to treat Helicobacter pylori infections. This combination is usually given with clarithromycin, another antibiotic.

[edit] History and development

Ranitidine was developed by Glaxo (now GlaxoSmithKline) in an effort to match the success of Smith, Kline & French (also now GlaxoSmithKline) with the first histamine H₂-receptor antagonist cimetidine. Ranitidine was the result of a rational drug-design process utilising the, by then, fairly refined model of the histamine H₂-receptor and quantitative structure-activity relationships (QSAR).

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 ten times the activity of cimetidine.

Ranitidine was introduced in 1981 and was the world's biggest-selling prescription drug by 1988. It has since largely been superseded by the even more effective proton pump inhibitors, with omeprazole becoming the biggest-selling drug for many years.