Dosing Safety Assessment for Augmentin 600/5 in a 45-Pound Child
The prescribed dose of 6 mL twice daily of Augmentin 600/5 (amoxicillin 600 mg/5 mL with clavulanate 42.9 mg/5 mL) is UNSAFE and significantly underdoses this 45-pound (20.4 kg) child.
Correct Dosing Calculation
For a 45-pound (20.4 kg) child, the FDA-approved dosing for Augmentin ES-600 is:
- Standard dose: 90 mg/kg/day of amoxicillin divided every 12 hours 1
- Calculation: 20.4 kg × 90 mg/kg/day = 1,836 mg/day
- Per dose: 918 mg every 12 hours
- Volume needed: Approximately 7.5 mL twice daily (since 5 mL contains 600 mg amoxicillin)
The prescribed 6 mL twice daily delivers only 720 mg per dose (1,440 mg/day total), which is only 78% of the recommended dose.
Why This Matters for Clinical Outcomes
Underdosing amoxicillin-clavulanate directly compromises treatment efficacy and promotes antibiotic resistance. The high-dose amoxicillin regimen (80-90 mg/kg/day) was specifically developed to achieve middle ear and sinus fluid concentrations that exceed the minimum inhibitory concentration (MIC) for penicillin-resistant Streptococcus pneumoniae 2.
For β-lactamase-producing Haemophilus influenzae and Moraxella catarrhalis, adequate clavulanate levels are essential 2. The 6 mL dose provides insufficient amoxicillin to overcome intermediate and highly resistant pneumococcal strains.
Correct Prescribing Based on Weight
According to FDA labeling for Augmentin ES-600 1:
| Body Weight | Correct Volume (twice daily) |
|---|---|
| 16 kg | 6.0 mL |
| 20 kg | 7.5 mL |
| 24 kg | 9.0 mL |
For this 20.4 kg child, the correct dose is 7.5 mL twice daily, not 6 mL.
Clinical Context and Indications
High-dose amoxicillin-clavulanate (90 mg/kg/day) is indicated for 2, 3, 4:
- Children under 2 years old
- Recent antibiotic exposure (within 30 days)
- Daycare attendance
- Geographic areas with >10% penicillin-resistant S. pneumoniae
- Moderate-to-severe infections
- Treatment failures on standard-dose amoxicillin
The Augmentin ES-600 formulation was specifically designed to deliver 90 mg/kg/day of amoxicillin with optimized clavulanate (6.4 mg/kg/day) to minimize diarrhea while maintaining efficacy 1.
Common Prescribing Pitfalls
Critical error to avoid: Do NOT substitute other Augmentin suspensions for ES-600. The 200 mg/5 mL and 400 mg/5 mL suspensions contain different clavulanate ratios and are NOT interchangeable 1. Using volume-based dosing from other formulations will result in incorrect dosing.
Storage reminder: Augmentin suspension must be refrigerated after reconstitution and discarded after 10 days. Heat exposure significantly degrades potency 5.
Recommendation
The prescription should be corrected to 7.5 mL twice daily for 10 days to achieve the evidence-based 90 mg/kg/day dosing that maximizes bacterial eradication and clinical cure rates while minimizing resistance selection 2, 1.