Augmentin Dosing for 8-Year-Old, 89 Pounds
For an 8-year-old child weighing 89 lb (40 kg), the appropriate dose of Augmentin 400/57 mg per 5 mL suspension depends on the indication and severity of infection: give 10 mL twice daily (standard dosing for 45 mg/kg/day) for mild-to-moderate infections, or 18 mL twice daily (high-dose 90 mg/kg/day) for severe infections or suspected resistant pathogens.
Dosing Calculation
Standard-Dose Regimen (45 mg/kg/day)
- Target dose: 45 mg/kg/day of amoxicillin component divided twice daily
- Calculation: 40 kg × 45 mg/kg/day = 1,800 mg/day
- Per dose: 900 mg twice daily
- Volume: 900 mg ÷ 400 mg/5 mL = 11.25 mL twice daily (round to 10-11 mL)
High-Dose Regimen (90 mg/kg/day)
- Target dose: 90 mg/kg/day of amoxicillin component divided twice daily
- Calculation: 40 kg × 90 mg/kg/day = 3,600 mg/day
- Per dose: 1,800 mg twice daily
- Volume: 1,800 mg ÷ 400 mg/5 mL = 22.5 mL twice daily (round to 20-22 mL)
However, note that the 400/57 mg per 5 mL formulation is NOT the high-dose ES-600 formulation 1. The ES-600 contains 600 mg amoxicillin and 42.9 mg clavulanate per 5 mL and is specifically designed for high-dose therapy.
Clinical Decision Algorithm
Use Standard-Dose (45 mg/kg/day = ~10 mL twice daily) if:
- First-line treatment for uncomplicated infection
- Child ≥2 years old
- No recent antibiotic use (within 30 days)
- Not attending daycare
- Mild-to-moderate severity 2
Use High-Dose (90 mg/kg/day) if:
- Age <2 years
- Recent antibiotic exposure (within 30 days)
- Daycare attendance
- Moderate-to-severe illness
- Treatment failure on standard dosing
- Geographic area with >10% penicillin-nonsusceptible S. pneumoniae 2
- Suspected β-lactamase-producing organisms (H. influenzae, M. catarrhalis) 3
For high-dose therapy in this 40 kg child, you should ideally switch to Augmentin ES-600 formulation (12 mL twice daily per FDA label) rather than using large volumes of the 400/57 formulation 1.
Important Caveats
Formulation Limitations
The 400/57 mg per 5 mL suspension contains 57 mg clavulanate per 5 mL, while ES-600 contains only 42.9 mg per 5 mL. These formulations are NOT interchangeable 1. Using high volumes of the 400/57 formulation to achieve 90 mg/kg/day amoxicillin will deliver excessive clavulanate, increasing diarrhea risk.
Practical Considerations
- Twice-daily dosing improves compliance compared to three-times-daily regimens (82.8% vs 73.3% adherence) 4
- Reduced diarrhea with twice-daily dosing: 9.6% vs 26.7% with three-times-daily 5
- Administer at the start of meals to minimize GI intolerance and enhance clavulanate absorption 1
- Shake suspension well before each dose 1
Resistance Considerations
For community-acquired pneumonia with β-lactamase-producing H. influenzae, guidelines recommend amoxicillin-clavulanate at 45 mg/kg/day in 3 doses OR 90 mg/kg/day in 2 doses 3. The higher dose provides better coverage against penicillin-intermediate S. pneumoniae (MIC 2-4 mcg/mL), achieving 85.7-100% bacteriologic eradication 1.
Maximum Dose
For children weighing ≥40 kg, do not exceed adult dosing: maximum 2,000 mg amoxicillin per dose 1.
Bottom Line
Give 10 mL of Augmentin 400/57 mg per 5 mL twice daily for standard therapy, or switch to ES-600 formulation (12 mL twice daily) if high-dose therapy is indicated. Do not attempt high-dose therapy with the 400/57 formulation due to excessive clavulanate content.