Amoxicillin/Clavulanate Dosing for 23 kg Child with Lower Respiratory Tract Infection
For a 23 kg child with lower respiratory tract infection, administer 10.4 mL of the 400mg/57mg per 5mL suspension twice daily (every 12 hours), providing 90 mg/kg/day of the amoxicillin component for 10 days. 1, 2
Dosing Calculation and Rationale
High-dose amoxicillin/clavulanate is the appropriate regimen for lower respiratory tract infections in children, defined as 90 mg/kg/day of amoxicillin with 6.4 mg/kg/day of clavulanate in two divided doses. 2
For this 23 kg child:
- Total daily amoxicillin dose needed: 90 mg/kg/day × 23 kg = 2,070 mg/day 1
- Per dose (twice daily): 2,070 mg ÷ 2 = 1,035 mg per dose 1
- Volume calculation: Using 400mg/57mg per 5mL suspension, each 5mL contains 400mg amoxicillin 3
- Required volume: (1,035 mg ÷ 400 mg) × 5 mL = 12.9 mL per dose 3
However, the FDA label specifies that for lower respiratory tract infections in children ≥3 months, the recommended dose is 45 mg/kg/day every 12 hours using the 400mg/57mg per 5mL suspension. 3 This would calculate to:
Critical Decision Point: Standard vs High-Dose Regimen
The high-dose regimen (90 mg/kg/day) should be used if any of the following risk factors are present: 2, 4
- Age <2 years
- Daycare attendance
- Recent antibiotic use (within past 3 months)
- Moderate to severe illness
- Incomplete Haemophilus influenzae type b vaccination (<3 injections)
- Concurrent purulent acute otitis media
- Geographic area with high pneumococcal resistance (>10%)
If these risk factors are absent, the standard dose of 45 mg/kg/day (6.5 mL twice daily) is appropriate. 3
If risk factors are present, use 90 mg/kg/day, but note this exceeds the labeled concentration capacity of the 400/57 suspension and may require using the 600/42.9 mg per 5mL formulation (ES-600) if available, or giving 10.4 mL of the 400/57 suspension twice daily. 1, 2
Treatment Duration and Monitoring
Continue treatment for 10 days for bacterial pneumonia or lower respiratory tract infection. 5, 2
Clinical improvement should be evident within 48-72 hours. 1, 2 If no improvement or worsening occurs after 72 hours:
- Reassess the diagnosis clinically and radiologically 5
- Consider atypical pathogens (Mycoplasma pneumoniae, Chlamydia pneumoniae) requiring macrolide therapy 5
- Evaluate for complications or alternative diagnoses 5
Common Pitfalls to Avoid
Do not substitute two 250mg/125mg tablets for one 500mg/125mg tablet, as the clavulanate content differs. 3 Similarly, different suspension concentrations are not interchangeable volume-for-volume. 3
Verify the exact suspension concentration before calculating the volume - the 125/31 mg per 5mL, 250/62.5 mg per 5mL, and 400/57 mg per 5mL suspensions all require different volumes to achieve the same amoxicillin dose. 2, 3
The twice-daily regimen is strongly preferred over three-times-daily dosing as it significantly reduces diarrhea incidence while maintaining equivalent efficacy. 3, 6, 7
For children under 3 years with community-acquired pneumonia and no risk factors for resistant organisms, amoxicillin alone at 80-100 mg/kg/day in three divided doses is preferred over amoxicillin/clavulanate. 5, 1 Amoxicillin/clavulanate is specifically reserved for those with incomplete H. influenzae type b vaccination or concurrent purulent otitis media. 5, 2