Ranitidine

Indications

Oral
Benign gastric and duodenal ulceration
Adult: Initially, 300 mg as a single daily dose at bedtime or 150 mg bid; 300 mg bid for 4 wk may be used in duodenal ulcer to improve healing). Treatment duration: 4-8 wk for benign gastric and duodenal ulceration; up to 8 wk in NSAID-associated ulceration. For prevention of NSAID-associated ulceration: 150 mg bid.
Child: 3-12 yr: 2-4 mg/kg (max: 150 mg) bid for 4-8 wk.
Renal impairment: Dosage reduction is required in severe renal impairment.

CrCl (ml/min)	Dosage Recommendation
≤20	Dosage should be halved.

Oral
H.pylori infection
Adult: 300 mg once daily or 150 mg bid in combination with amoxicillin 750 mg tid and metronidazole 500 mg tid given for 2 wk. Treatment with ranitidine may be continued for a further 2 wk.
Renal impairment: Dosage reduction is required in severe renal impairment.

CrCl (ml/min)	Dosage Recommendation
≤20	Dosage should be halved.

Oral
Gastro-oesophageal reflux disease
Adult: 150 mg bid or 300 mg at bedtime for up to 8 wk, may increase to 150 mg four times daily for 12 wk in severe cases.
Child: 5-10 mg/kg daily, given in 2 divided doses.
Renal impairment: Dosage reduction is required in severe renal impairment.

CrCl (ml/min)	Dosage Recommendation
≤20	Dosage should be halved.

Oral
Hypersecretory conditions
Adult: Initially, 150 mg bid/tid increased to 6 g daily if necessary.
Renal impairment: Dosage reduction is required in severe renal impairment.

CrCl (ml/min)	Dosage Recommendation
≤20	Dosage should be halved.

Oral
Acid aspiration during general anaesthesia
Adult: 150 mg given 2 hr before induction of anaesthesia and preferably, an additional dose on the previous evening.
Renal impairment: Dosage reduction is required in severe renal impairment.

CrCl (ml/min)	Dosage Recommendation
≤20	Dosage should be halved.

Oral
Dyspepsia
Adult: 75 mg repeated if necessary up to 4 doses daily. Max: 2 wk of continuous use at each time. For chronic episodic dyspepsia: 150 mg bid for up to 6 wk.
Renal impairment: Dosage reduction is required in severe renal impairment.

CrCl (ml/min)	Dosage Recommendation
≤20	Dosage should be halved.

Parenteral
Prophylaxis of acid aspiration during general anaesthesia
Adult: 50 mg IV/IM given 45-60 minutes before the induction of anaesthesia.
Renal impairment: Dosage reduction is required in severe renal impairment.

CrCl (ml/min)	Dosage Recommendation
≤20	Doses should be halved.

Intravenous
Hypersecretory conditions
Adult: Initially, 1 mg/kg/hr IV infusion, may increase by increments of 0.5 mg/kg/hr starting after 4 hr if necessary.
Renal impairment: Dosage reduction is required in severe renal impairment.

CrCl (ml/min)	Dosage Recommendation
≤20	Dosage should be halved.

Intravenous
Stress ulceration of upper gastrointestinal tract
Adult: 50 mg by slow IV Inj as priming dose followed by 125-250 mcg/kg/hr as continuous IV infusion then transfer to oral dose of 150 mg bid once oral feeding is resumed.
Renal impairment: Dosage reduction is required in severe renal impairment.

CrCl (ml/min)	Dosage Recommendation
≤20	Dosage should be halved.

Special Populations: Adjust dose in patients with renal impairment: 150 mg/day orally or 25 mg for parenteral administration.

Contraindications

Porphyria.

Warnings / Precautions

Exclude malignancy before treating gastric ulcer. Renal and hepatic impairment. Infants, pregnancy and lactation.

Adverse Reactions

Headache, dizziness. Rarely hepatitis, thrombocytopaenia, leucopaenia, hypersensitivity, confusion, gynaecomastia, impotence, somnolence, vertigo, hallucinations.
Potentially Fatal: Anaphylaxis, hypersensitivity reactions.

Overdose Reactions

May lead to muscular tremors, vomiting and rapid respiration.

Drug Interactions

Antacids may interfere with absorption. May decrease the GI absorption of ketoconazole. Smoking may decrease the plasma levels of ranitidine. May cause an increase in the bioavailability of furosemide.
See Below for More ranitidine Drug Interactions

Mechanism of Actions

Ranitidine blocks histamine H₂-receptors in the stomach and prevents histamine-mediated gastric acid secretion. It does not affect pepsin secretion, pentagastrin-stimulated factor secretion or serum gastrin.
Absorption: 50% with peak plasma concentrations after 2-3 hr (oral); rapid with peak plasma concentrations after 15 min (IM).
Distribution: Widely distributed. Crosses the placental barrier and enters breast milk. Protein-binding: 20%
Metabolism: Hepatic; converted to N-oxide, S-oxide and desmethylranitidine.
Excretion: Urine (as unchanged drug) within 24 hr; faeces; 2-3 hr (elimination half-life).

Administration

May be taken with or without food.

ATC Classification

A02BA02 - ranitidine ; Belongs to the class of H2-receptor antagonists. Used in the treatment of peptic ulcer and gastro-oesophageal reflux disease (GERD).