Dosing Recommendation for Co-amoxiclav Suspension
Give 15 mL of co-amoxiclav suspension 457 mg/5 mL every 12 hours for 7 days.
Calculation Rationale
For this 11-year-old child weighing 30 kg, the appropriate dosing is based on FDA-approved guidelines for co-amoxiclav (amoxicillin/clavulanate) suspension 1.
Dose Selection
- Target dose: 45 mg/kg/day of amoxicillin component (divided every 12 hours) for respiratory tract infections and more severe infections 1
- Daily requirement: 30 kg × 45 mg/kg/day = 1,350 mg amoxicillin per day
- Per-dose requirement: 1,350 mg ÷ 2 doses = 675 mg amoxicillin per dose
Volume Calculation
The suspension contains 457 mg amoxicillin per 5 mL (this is the 400 mg/57 mg formulation, where 400 mg refers to amoxicillin trihydrate equivalent to 400 mg amoxicillin, but the actual amoxicillin content is 457 mg per 5 mL when accounting for the complete formulation).
- Concentration: 457 mg amoxicillin / 5 mL = 91.4 mg/mL
- Volume needed: 675 mg ÷ 91.4 mg/mL = 7.4 mL per dose
However, rounding to practical measurement: 7.5 mL per dose provides 685.5 mg amoxicillin (45.7 mg/kg/dose), which is appropriate.
Alternative calculation: If using the 400 mg/57 mg per 5 mL formulation labeling:
- 675 mg ÷ 80 mg/mL = 8.4 mL, which rounds to 8.5 mL per dose
Clinical Context
The FDA label specifies that for otitis media, sinusitis, lower respiratory tract infections, and more severe infections, the recommended dose is 45 mg/kg/day every 12 hours using the 400 mg/57 mg per 5 mL formulation 1. This twice-daily regimen is preferred as it is associated with significantly less diarrhea compared to three-times-daily dosing 1.
For a 30 kg child:
- Standard dosing: 8-8.5 mL every 12 hours achieves the target of 45 mg/kg/day
- Duration: 7 days is appropriate for most respiratory infections
Important Caveats
- The suspension should be given with food to enhance clavulanate absorption and reduce gastrointestinal side effects 1
- Ensure proper reconstitution of the suspension before dispensing
- The 400 mg/57 mg formulation contains aspartame and should not be used in phenylketonuric patients 1
- Monitor for common adverse effects including diarrhea, nausea, and skin rash
- This child weighs less than 40 kg, so pediatric dosing (not adult tablet dosing) is appropriate 1
Final Answer: 8 mL every 12 hours (practical rounding) or 7.5 mL every 12 hours (precise calculation) - either provides adequate dosing within the recommended 45 mg/kg/day range.