Chemical formula: C₁₃H₂₂N₄O₃S Molecular mass: 314.4 g/mol PubChem compound: 3001055
Ranitidine interacts in the following cases:
Accumulation of ranitidine with resulting elevated plasma concentrations will occur in patients with renal impairment (creatinine clearance less than 50 ml/min). Accordingly, it is recommended that the daily dose of ranitidine in such patients should be 150 mg at night for 4-8 weeks. The same dose should be used for maintenance treatment, if necessary. If an ulcer has not healed after treatment, 150 mg twice daily dosage should be instituted followed, if need be, by maintenance treatment of 150 mg at night.
There have been reports of altered prothrombin time with coumarin anticoagulants (e.g. warfarin). Due to the narrow therapeutic index, close monitoring of increased or decreased prothrombin time is recommended during concurrent treatment with ranitidine.
The bioavailability of certain drugs may be affected by coadministration of ranitidine. This can result in a decrease in absorption of ketoconazole, atazanavir, delavirdine, gefitinib.
Since ranitidine is partially eliminated by the cationic system, it may affect the clearance of other drugs eliminated by this route. High doses of ranitidine (e.g. such as those used in the treatment of Zollinger-Ellison syndrome) may reduce the excretion of procainamide and N-acetylprocainamide resulting in increased plasma level of these drugs.
If high doses (2 g) of sucralfate are co-administered with ranitidine the absorption of the latter may be reduced. This effect is not seen if sucralfate is taken after an interval of 2 hours.
The bioavailability of certain drugs may be affected by coadministration of ranitidine. This can result in an increase in absorption of triazolam, midazolam, glipizide.
Ranitidine crosses the placenta but therapeutic doses administered to obstetric patients in labour or undergoing caesarean section have been without any adverse effect on labour, delivery or subsequent neonatal progress. Like other drugs, ranitidine should only be used during pregnancy if considered essential.
Ranitidine is excreted in human breast milk. Like other drugs ranitidine should only be used during breast-feeding if considered essential.
There are no data on the effects of ranitidine on human fertility. There were no effects on male and female fertility in animal studies.
None reported.
The following convention has been utilised for the classification of undesirable effects: very common (≥1/10), common (≥1/100, <1/10), uncommon (≥1/1000, ≤1/100), rare (≥1/10,000, ≤1/1000), very rare (≤1/10,000). Adverse event frequencies have been estimated from spontaneous reports from post-marketing data.
Very Rare: Blood count changes (leucopenia, thrombocytopenia). These are usually reversible. Agranulocytosis or pancytopenia, sometimes with marrow hypoplasia or marrow aplasia.
Rare: Hypersensitivity reactions (urticaria, angioneurotic oedema, fever, bronchospasm, hypotension and chest pain).
Very Rare: Anaphylactic shock.
Not known: Dyspnoea.
These events have been reported after a single dose.
Very Rare: Reversible mental confusion, depression and hallucinations.
These have been reported predominantly in severely ill patients, in elderly and in nephropatic patients.
Very Rare: Headache (sometimes severe), dizziness and reversible involuntary movement disorders.
Very Rare: Reversible blurred vision.
There have been reports of blurred vision, which is suggestive of a change in accommodation.
Very Rare: As with other H2 receptor antagonists bradycardia, A-V block and tachycardia.
Very Rare: Vasculitis.
Uncommon: Abdominal pain, constipation, nausea (these symptoms mostly improved during continued treatment).
Very Rare: Acute pancreatitis, diarrhoea
Rare: Transient and reversible changes in liver function tests.
Very Rare: Hepatitis (hepatocellular, hepatocanalicular or mixed) with or without jaundice, these were usually reversible.
Rare: Skin Rash.
Very Rare: Erythema multiforme, alopecia.
Very Rare: Musculoskeletal symptoms such as arthralgia and myalgia.
Rare: Elevation of plasma creatinine (usually slight; normalised during continued treatment)
Very Rare: Acute interstitial nephritis.
Very Rare: Reversible impotence, breast symptoms and breast conditions (such as gynaecomastia and galactorrhoea).
The safety of ranitidine has been assessed in children aged 0 to 16 years with acid-related disease and was generally well tolerated with an adverse event profile resembling that in adults. There are limited long term safety data available, in particular regarding growth and development.
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