Amoxicillin Dosing for Pediatric Pneumonia
For babies with pneumonia, administer amoxicillin 90 mg/kg/day divided into 2 doses (given every 12 hours) using the 100 mg/ml suspension, which provides optimal coverage against Streptococcus pneumoniae including resistant strains. 1, 2
Weight-Based Dosing Calculation
To calculate the exact dose for your patient:
- Total daily dose: 90 mg/kg/day 1, 2
- Divide into 2 doses: Give every 12 hours 1, 2
- Using 100 mg/ml suspension: Each ml contains 100 mg of amoxicillin 1
Example calculation for a 6 kg infant:
- 6 kg × 90 mg/kg/day = 540 mg/day total
- 540 mg ÷ 2 doses = 270 mg per dose
- 270 mg ÷ 100 mg/ml = 2.7 ml per dose, given every 12 hours 1
Dosing by Age Group
Infants ≥3 months old:
- Standard dose: 90 mg/kg/day divided every 12 hours for pneumonia 1, 2
- Maximum daily dose: 4000 mg (4 grams) per day regardless of weight 1, 3
Infants <3 months old:
- Reduced dose: 30 mg/kg/day divided every 12 hours due to immature renal function 3
- This lower dose accounts for incomplete renal development affecting amoxicillin elimination 3
Treatment Duration and Monitoring
- Duration: 10 days for pneumonia 1, 2
- Clinical improvement expected: Within 48-72 hours of starting therapy 1, 2
- If no improvement by 48-72 hours: Reevaluate for complications, resistant organisms, or alternative diagnoses 1, 2
Rationale for High-Dose Regimen
The 90 mg/kg/day dosing (rather than the older 40-45 mg/kg/day) is critical because:
- Overcomes penicillin-resistant S. pneumoniae: The most common bacterial cause of pediatric pneumonia 2, 4
- Maintains therapeutic levels: Achieves plasma concentrations above the MIC for >50% of the dosing interval 5, 6
- Underdosing is a common and dangerous error: Using 40-45 mg/kg/day instead of 90 mg/kg/day leads to treatment failure 2
Special Considerations
When to use amoxicillin-clavulanate instead:
- Not fully immunized against Haemophilus influenzae type b or Streptococcus pneumoniae 2
- Concurrent purulent otitis media 1
- Suspected β-lactamase-producing organisms 1, 2
Penicillin allergy management:
- Non-severe allergy: Consider cephalosporins (cefdinir, cefpodoxime, cefuroxime) under supervision 1, 2
- Severe/anaphylactic allergy: Use azithromycin or levofloxacin (age-appropriate) 1, 2
- Never use amoxicillin if there is documented penicillin or amoxicillin allergy with anaphylaxis 1
Administration Instructions
- Give at the start of meals to minimize gastrointestinal intolerance 3
- Shake suspension well before each dose 3
- Refrigeration preferred but not required after reconstitution 3
- Discard unused suspension after 14 days 3
- Can mix with formula, milk, or juice if needed, but administer immediately 3
Common Pitfalls to Avoid
- Underdosing: Using 40-45 mg/kg/day instead of the recommended 90 mg/kg/day is the most common error 2
- Inappropriate macrolide use: Do not use macrolides as first-line for presumed bacterial pneumonia in children <5 years 2
- Premature discontinuation: Complete the full 10-day course even if symptoms improve earlier 1, 2
- Failure to reassess: If no improvement by 48-72 hours, reevaluate rather than continuing ineffective therapy 1, 2