Co-Amoxiclav 457mg/5ml Dosing for 20kg Pediatric Patient
For a 20kg child, administer 10ml of co-amoxiclav 457mg/5ml suspension every 12 hours for 7 days, providing 90mg/kg/day of the amoxicillin component (1800mg total daily dose). 1, 2
Dosing Calculation and Rationale
The 457mg/5ml formulation is specifically designed for high-dose twice-daily dosing in pediatric patients. 2 This concentration provides the recommended 14:1 ratio of amoxicillin to clavulanate (90mg/6.4mg per kg/day) when dosed appropriately. 1, 2
Weight-Based Calculation:
- Target dose: 90mg/kg/day of amoxicillin component divided into 2 doses 1, 2
- For 20kg child: 20kg × 90mg/kg = 1800mg amoxicillin daily
- Per dose: 1800mg ÷ 2 = 900mg per dose
- Volume calculation: 900mg ÷ 457mg/5ml = 9.85ml ≈ 10ml per dose 1, 2
Clinical Indications for High-Dose Regimen
High-dose co-amoxiclav (90mg/kg/day) is indicated when any of the following risk factors are present: 1, 2
- Age <2 years
- Daycare attendance
- Recent antibiotic use within past 30 days
- Incomplete Haemophilus influenzae type b vaccination
- Geographic area with >10% penicillin-resistant S. pneumoniae
- Moderate to severe illness
- Concurrent purulent acute otitis media 1, 2
The high-dose formulation achieves plasma concentrations above the MIC for at least 34% of the dosing interval, which is necessary for efficacy against penicillin-resistant S. pneumoniae with MICs up to 4 mcg/ml. 3
Treatment Duration and Monitoring
Continue treatment for the full 7-day course as prescribed, though 10 days is preferred for pneumonia or severe respiratory infections. 4, 1
Expected Clinical Response:
- Clinical improvement should be evident within 48-72 hours of starting therapy 1, 2
- If no improvement or worsening occurs after 72 hours, reevaluate the diagnosis and consider alternative pathogens or complications 1, 2
- Fever typically resolves within 24-48 hours for pneumococcal infections 1
Critical Dosing Considerations
The maximum daily dose should not exceed 4000mg (4g) of amoxicillin component regardless of weight. 1 For this 20kg patient, the calculated dose of 1800mg/day is well below this maximum.
Verify the suspension concentration before dispensing—the 457mg/5ml formulation is distinct from other co-amoxiclav suspensions (125/31 or 250/62). 2 Using the wrong concentration will result in significant underdosing or overdosing.
Common Pitfalls to Avoid
Do not use standard-dose regimens (45mg/kg/day) when high-dose therapy is indicated, as this leads to treatment failure with resistant organisms. 1, 2 The 457mg/5ml formulation is specifically designed for high-dose therapy and should not be dosed at lower volumes.
Do not confuse age-based dosing recommendations (which apply to older formulations) with weight-based dosing for the 457mg/5ml preparation. 2 This formulation requires precise weight-based calculation.
The twice-daily (every 12 hours) dosing schedule is as effective as three-times-daily dosing and causes less diarrhea. 5, 6 Do not split this into three daily doses.
Adverse Effects
The most common adverse effects are gastrointestinal disturbances including diarrhea, nausea, and vomiting. 1 The 14:1 ratio formulation (90/6.4 mg/kg/day) causes less diarrhea than other amoxicillin-clavulanate preparations while maintaining efficacy. 2
Hypersensitivity reactions including rash and urticaria may occur. 1 For patients with non-anaphylactic penicillin allergy, second- or third-generation cephalosporins may be considered as alternatives. 1