Dose and Administration ^1-3

1. Intravenous (slow infusion over 15 minutes)
   1. Preterm infants <32 weeks and <7 days:  0.5mg/kg every 12 hours
   2. Term infants:  0.5mg/kg every 8 hours
2. Oral:  2mg/kg every 8 hours

Indications ⁴

Safety and efficacy in children has not been established in clinical trials.

1. Treatment of acute gastrointestinal bleeding or stress ulcers.

Contraindications and Precautions ^4,5

1. Known hypersensitivity to ranitidine.
2. Caution in neonates with renal impairment (see "Special Considerations").
3. Possible necrotising enterocolitis (see "Special Considerations").

Clinical Pharmacology

Ranitidine is a highly effective, rapidly acting histamine H2 receptor antagonist. It inhibits both basal stimulated gastric secretions (volume, acid and pepsin content reduced).

Peak plasma concentration occurs 15 minutes after an IV dose and 1-3 hours after an oral dose (in adults).  Oral administration is not influenced by food. Ranitidine is not extensively metabolised; elimination is predominantly renal with 70% of an IV dose and 35-70% of an oral dose eliminated unchanged.  Normal elimination half-life in children is 2-3 hours but is prolonged in patients with renal insufficiency. Very limited data available describing pharmacokinetics and pharmacodynamics in the newborn.

Possible Adverse Effects

1. Rarely, bradycardia or arrhythmias if administration is too rapid.
2. Hepatitis with or without jaundice (rare, and usually reversible).
3. Diarrhoea (rarely)
4. Skin rash.

Drug Interactions ⁶

1. Antacids:  separate antacid and oral ranitidine doses by an hour.
2. Phenytoin: monitor for signs of phenytoin toxicity.

Special Considerations ^5,7

1. Severe renal impairment: use half the normal dose
2. Ranitidine has been associated with necrotising enterocolitis. Whilst this may be because infants with early symptoms of NEC might be treated with ranitidine before the diagnosis is apparent, randitine may potentially contribute to NEC by reducing gastric pH.¹¹