Common Pediatric Drug Dosages
General Principles of Pediatric Dosing
Children are not small adults, and simple weight-based scaling from adult doses is inappropriate—children aged 2 years and older are physiologically mature but differ in size, while neonates and infants require special consideration due to immature drug elimination pathways. 1
Key Dosing Considerations
- For children under 30 kg: Calculate dose as (weight × 2)% of adult dose 2
- For children over 30 kg: Calculate dose as (weight + 30)% of adult dose 2
- Neonates and infants under 2 years: Require maturation-adjusted dosing due to immature hepatic and renal function 1
- Simple mg/kg scaling results in underdosing in children and overdosing in neonates 1
Common Antibiotic Dosages
Amoxicillin (Oral)
Mild to Moderate Infections 3
- Children ≥3 months and <40 kg: 25 mg/kg/day divided every 12 hours OR 20 mg/kg/day divided every 8 hours 3
- Children ≥40 kg and adults: 500 mg every 12 hours OR 250 mg every 8 hours 3
Severe Infections 3
- Children ≥3 months and <40 kg: 45 mg/kg/day divided every 12 hours OR 40 mg/kg/day divided every 8 hours 3
- Children ≥40 kg and adults: 875 mg every 12 hours OR 500 mg every 8 hours 3
Neonates <3 months 3
- Maximum dose: 30 mg/kg/day divided every 12 hours due to immature renal function 3
- Continue treatment minimum 48-72 hours beyond symptom resolution 3
Amoxicillin-Clavulanate (Co-amoxiclav)
For UTI and Other Infections 4
- Standard dosing: 20-40 mg/kg/day (amoxicillin component) divided into 3 doses 4
- Alternative high-dose regimen: 45 mg/kg/day divided into 3 doses OR 90 mg/kg/day divided into 2 doses 4
- Maximum daily dose: Do not exceed 4000 mg of amoxicillin component 4
Ampicillin (IV/IM)
Neonatal Dosing 5
- ≤7 days old and ≤2000 g: 50 mg/kg/day divided every 12 hours 5
- ≤7 days old and >2000 g: 75 mg/kg/day divided every 8 hours 5
- >7 days old and <1200 g: 50 mg/kg/day divided every 12 hours 5
- >7 days old and 1200-2000 g: 75 mg/kg/day divided every 8 hours 5
- >7 days old and >2000 g: 100 mg/kg/day divided every 6 hours 5
Neonatal Sepsis 6
- Empiric therapy for neonates 8-21 days: 150 mg/kg/day divided every 8 hours 6
- For suspected meningitis: 300 mg/kg/day divided every 6 hours 6
Infants and Children 5
- Standard dosing: 100-200 mg/kg/day divided every 6 hours 5
Ceftriaxone (IV/IM)
Neonatal Dosing 7
- ≤7 days old: 50 mg/kg/day given every 24 hours 7
- >7 days old and ≤2000 g: 50 mg/kg/day given every 24 hours 7
- >7 days old and >2000 g: 50-75 mg/kg/day given every 24 hours 7
- CRITICAL: Never use in hyperbilirubinemic neonates due to kernicterus risk 7
Pediatric Dosing by Indication 7
- Mild to moderate infections: 50-75 mg/kg/day once daily or divided every 12-24 hours 7
- Severe infections/pneumonia: 50-100 mg/kg/day once daily or divided every 12-24 hours 7
- Bacterial meningitis: 100 mg/kg/day divided every 12-24 hours (maximum 4 g daily) 7
- Severe sepsis: 80-100 mg/kg/day (use higher end of dosing range) 7
- Maximum dose: Never exceed 4 g daily regardless of weight 7
Special Considerations for Severe Sepsis 7
- If staphylococcal infection suspected: Add flucloxacillin 50 mg/kg every 6 hours plus gentamicin 7.5 mg/kg daily 7
- If Listeria suspected: Add ampicillin 50 mg/kg every 6 hours 7
Ceftazidime (IV)
Neonatal Dosing 5
- 0-4 weeks and <1200 g: 100 mg/kg/day divided every 12 hours 5
- ≤7 days and 1200-2000 g: 100 mg/kg/day divided every 12 hours 5
- ≤7 days and >2000 g: 100-150 mg/kg/day divided every 8-12 hours 5
- >7 days and ≥1200 g: 150 mg/kg/day divided every 8 hours 5
Neonatal Sepsis 6
- Empiric therapy for neonates 8-21 days: 150 mg/kg/day divided every 8 hours 6
Infants and Children ≤12 years 5
- Standard dosing: 100-150 mg/kg/day divided every 8 hours 5
Gentamicin (IV)
Neonatal Dosing 5
- 0-4 weeks and <1200 g: 7.5 mg/kg every 18-24 hours 5
- ≤7 days and 1200-2000 g: 7.5 mg/kg every 12 hours 5
- ≤7 days and >2000 g: 7.5-10 mg/kg every 12 hours 5
- >7 days and <1200 g: 7.5-10 mg/kg every 8-12 hours 5
- >7 days and >2000 g: 10 mg/kg every 8 hours 5
Neonatal Sepsis 6
- Empiric therapy for neonates 8-21 days: 4 mg/kg/dose every 24 hours (once daily dosing) 6
Infants and Children 5
- Standard dosing: 15-22.5 mg/kg/day divided every 8 hours 5
- For cystic fibrosis or febrile neutropenia: May require 30 mg/kg/day divided every 8 hours based on serum levels 5
Antituberculosis Medications
Isoniazid
Daily Dosing 5
Intermittent Dosing (2-3 times weekly) 5
Rifampin
Daily Dosing 5
Intermittent Dosing (2-3 times weekly) 5
Pyrazinamide
Daily Dosing 5
- Children: 15-30 mg/kg (maximum 2.0 g) 5
Twice Weekly Dosing 5
- Children: 50 mg/kg (maximum 4 g) 5
Ethambutol
Daily Dosing 5
- Children: 15-20 mg/kg daily (maximum 1.0 g) 5
Twice Weekly Dosing 5
- Children: 50 mg/kg (maximum 4 g) 5
Important Note: Children weighing more than 40 kg should be dosed as adults 5
Urinary Tract Infection Treatment
Oral Antibiotic Options for Pediatric UTI
Cephalexin 4
- Dosing: 50-100 mg/kg/day divided into 4 doses 4
Cefixime 4
- Dosing: 8 mg/kg/day as a single dose 4
Cefpodoxime 4
- Dosing: 10 mg/kg/day divided into 2 doses 4
Cefprozil 4
- Dosing: 30 mg/kg/day divided into 2 doses 4
Treatment Duration 4
- Recommended duration: 7-14 days for all pediatric UTIs 4
- Shorter courses (1-3 days) are inferior for febrile UTIs 4
Critical Pitfalls to Avoid
- Never use ceftriaxone in hyperbilirubinemic neonates due to displacement of bilirubin and kernicterus risk 6, 7
- Do not use simple mg/kg scaling from adult doses as this underdoses children and overdoses neonates 1
- Avoid lower-end dosing for severe infections such as sepsis or meningitis—always use the higher recommended range 7
- Ensure minimum 10 days treatment for Streptococcus pyogenes infections to prevent acute rheumatic fever 3
- Adjust doses in renal impairment particularly for renally eliminated drugs like aminoglycosides and beta-lactams 5
- Continue treatment 48-72 hours beyond symptom resolution or bacterial eradication 3