Ranitidine
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Ranitidine
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| Systematic (IUPAC) name | |
| N-(2-[(5-[(dimethylamino)methyl]furan-2-yl)methylthio]ethyl)-N-methyl-2-nitroethene-1,1-diamine | |
| Identifiers | |
| CAS number | |
| ATC code | A02 |
| PubChem | |
| DrugBank | |
| ChemSpider | |
| 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 | |
| Pregnancy cat. |
B1(AU) |
| Legal status |
Pharmacy Only (S2)(AU) OTC(US) P/POM (UK) |
| Routes | Oral, IV |
Ranitidine hydrochloride (INN) (pronounced /rəˈnɪtɨdiːn/) is a histamine H2-receptor antagonist that inhibits stomach acid production. It is commonly used in treatment of peptic ulcer disease (PUD) and gastroesophageal reflux disease (GERD). Ranitidine is also used alongside fexofenadine and other antihistamines for the treatment of skin conditions such as hives. Ranitidine is currently marketed under the brand name Zantac by GlaxoSmithKline and other brand names by various pharmaceutical companies.
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[edit] Clinical Use
Dosage:150mg night time for prophylaxis of ulcer;300mg night time(preferred)or150mg bd for treatment of ulcer(but not used now for curing ulcer after PPI's invention,however used routinely for prophylaxis) 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, packs containing 7 or 14 doses of the 150 mg tablet are available in supermarkets, 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, an antibiotic.
[edit] History and Development
Ranitidine was developed by Glaxo in an effort to match the success of Smith, Kline & French (prior to the merger of the two companies into GlaxoSmithKline) with the first histamine H2-receptor antagonist cimetidine. Ranitidine was the result of a rational drug-design process using what was by then a 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 has 10% the affinity that cimetidine has to CYP450 so it causes fewer side effects, but other H2 blockers Famotidine and Nizatidine have no CYP450 significant interactions.[1]
Ranitidine was introduced in 1981 and was the world's greatest-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.
[edit] Interference with Amphetamine
Ranitidine increases absorption and decreases excretion of amphetamines. Ranitidine can also be taken separately with amphetamines based in sulphate (amphetamine sulphate) to increase its central effects and half-life.[2]
Ranitidine increases oral absorption of triazolam in both young and older people. This effect is likely caused by elevation of gastrointestinal pH, allowing for greater absorption of acid-labile triazolam. Ranitidine-Coadministration of ranitidine increased the maximum plasma concentration of triazolam by 30%, increased the area under the concentration curve by 27%, and increased half-life by 3.3%. Caution is recommended during coadministration with triazolam. Thus this co-administration can lead to an overdose of triazolam which can lead to somnolence, confusion, impaired coordination, coma and death.
[edit] References
- ^ Goodman and Gilman's page 972 11th addition
- ^ Positive Predictive Values of Abused Drug Immunoassays on the Beckman Synchron in a Veteran Population
[edit] External links
- [1] - Consumer information on Zantac from the manufacturer.
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