Famotidine Dosing in Infants
For infants with gastroesophageal reflux disease (GERD), famotidine should be dosed at 0.5 mg/kg per dose, with frequency adjusted based on age: once daily for infants <3 months and every 12 hours for infants ≥3 months. 1, 2
Age-Based Dosing Algorithm
Infants <3 Months of Age
- Dose: 0.5 mg/kg once daily 2
- Rationale: Younger infants have decreased plasma and renal clearance of famotidine due to immature renal function, requiring less frequent dosing 2
Infants ≥3 Months to 12 Months of Age
- Dose: 0.5 mg/kg every 12 hours 1, 2
- Rationale: Pharmacokinetic parameters in infants >3 months are similar to older children and adults, allowing for twice-daily dosing 2
Route of Administration
- Intravenous: 0.5 mg/kg per dose at age-appropriate intervals 2, 3
- Oral: 0.5 mg/kg per dose at age-appropriate intervals 1, 2
- Bioavailability: Oral bioavailability in infants is similar to adult values, making oral administration equally effective when feasible 2
Dose Escalation Considerations
- Higher dose option: 1.0 mg/kg per dose may be more efficacious in some infants who do not respond adequately to 0.5 mg/kg 1
- Individualization: If symptoms persist after 2-4 weeks on standard dosing, consider increasing to 1.0 mg/kg per dose at the same frequency 1
- Evidence: The 1.0 mg/kg dose showed significant improvements in crying time, regurgitation frequency, and regurgitation volume in clinical trials 1
Special Clinical Situations
Stress Ulcers in Neonates
- Dose: 0.5 mg/kg IV every 12 hours 3
- Duration: Continue until hematemesis/vomiting ceases (typically 24-48 hours), then once daily for 2 additional days 3
- Efficacy: 96.3% of neonates had cessation of bleeding within 24 hours 3
Peptic Esophagitis
- Dose: 1 mg/kg once daily, administered before supper 4
- Duration: 6 months of treatment showed 91.6% symptom resolution and 70.8% histological healing 4
Safety Profile
Common adverse effects in infants include: 1
- Agitation or irritability (most common, manifested as head-rubbing in some cases)
- Somnolence
- Anorexia
- Headache
Important safety note: No serious adverse events have been reported in controlled trials, and famotidine does not affect hepatic cytochrome P-450 enzymes, unlike cimetidine 5
Monitoring Parameters
- Gastric pH: Should increase from baseline ~2.0 to >5.0 within 6-12 hours of dosing 3
- Clinical response: Assess regurgitation frequency, volume, and crying time at 2-4 week intervals 1
- Laboratory monitoring: Routine monitoring of white cell count, platelet count, and hepatic enzymes is not required for short-term use 3
Critical Pitfalls to Avoid
- Do not use adult dosing schedules in infants <3 months—their reduced renal clearance necessitates once-daily dosing 2
- Do not assume treatment failure before allowing adequate time for response (typically 2-4 weeks) 1
- Do not overlook agitation/irritability as a potential drug-related adverse effect rather than worsening GERD 1