What is the recommended dose of ranitidine (histamine H2-receptor antagonist) syrup for a 5-year-old child with acute gastroenteritis and severe gastritis?

Ranitidine Syrup Dosing in Children

For pediatric patients with gastroenteritis and gastritis, ranitidine syrup should be administered at 5-10 mg/kg/day divided into 2-3 doses, which for a typical 5-year-old (approximately 18-20 kg) translates to approximately 30-50 mg given 2-3 times daily. 1

FDA-Approved Pediatric Dosing

• Ranitidine is FDA-approved for children aged 1 month to 16 years at a dosage of 5-10 mg/kg/day divided into 2-3 doses for GERD and erosive esophagitis 1
• The maximum daily dose should not exceed 300 mg/day 1
• The acid-inhibiting effects last approximately 6 hours, necessitating 2-3 times daily administration 2

Specific Dosing for a 5-Year-Old Child

For a 5-year-old child weighing approximately 18-20 kg:

• Lower end dosing (5 mg/kg/day): 90-100 mg/day divided into 2-3 doses = 30-35 mg per dose given 3 times daily, or 45-50 mg per dose given twice daily 1
• Higher end dosing (10 mg/kg/day): 180-200 mg/day divided into 2-3 doses = 60-70 mg per dose given 3 times daily, or 90-100 mg per dose given twice daily 1

Important Clinical Considerations

Ranitidine is less effective than proton pump inhibitors (PPIs) for symptom relief and healing of erosive esophagitis in children 2. However, for acute gastroenteritis with gastritis, ranitidine may be appropriate as initial therapy given:

• Tachyphylaxis (diminishing response) develops within 6 weeks of treatment initiation, limiting long-term use 2
• The medication is available in peppermint-flavored syrup formulation, facilitating administration in children 2

Treatment Algorithm for Pediatric Gastritis

1. For mild, intermittent symptoms: Start with ranitidine 5 mg/kg/day divided in 2-3 doses along with lifestyle modifications 2

2. For moderate to severe symptoms or lack of response after 2-4 weeks: Switch to PPI therapy (omeprazole 0.7-3.3 mg/kg/day), as PPIs are more effective than H2-receptor antagonists 2

3. For refractory cases: Consider referral to pediatric gastroenterology 2

Critical Pitfalls to Avoid

• Do not use ranitidine in neonates (<1 month of age) as there is insufficient pharmacokinetic data to make dosing recommendations 1
• Avoid long-term maintenance therapy with ranitidine due to rapid development of tachyphylaxis within 6 weeks 2
• Be aware of increased risk of community-acquired pneumonia, gastroenteritis, and candidemia associated with H2-receptor antagonist use 2
• Adjust dosing in renal impairment: For creatinine clearance <50 mL/min, reduce frequency to every 24 hours 1

Administration Guidance

• Ranitidine syrup should be given as needed for symptom relief in acute gastroenteritis 1
• The medication can be administered with or without food 1
• For optimal effect in GERD, consider administering 30 minutes before meals, though this timing is more critical for PPIs than H2-receptor antagonists 2