Amoxicillin Dosing for 16kg Child with Mild URI
For this 16kg child with a mild upper respiratory infection, prescribe amoxicillin 360 mg (22.5 mg/kg/dose) twice daily, which provides a total daily dose of 45 mg/kg/day divided into 2 doses.
Dosing Rationale
The recommended dose for mild to moderate respiratory tract infections in children is 45 mg/kg/day divided into 2 doses (BID) 1. This aligns with both the Infectious Diseases Society of America guidelines and FDA labeling for pediatric respiratory infections 2, 3.
Calculation for this patient:
- Weight: 16 kg
- Total daily dose: 16 kg × 45 mg/kg = 720 mg/day
- Per dose (BID): 720 mg ÷ 2 = 360 mg per dose
- Dosing schedule: 360 mg every 12 hours 1, 3
Important Dosing Considerations
When to use higher dosing:
- The 90 mg/kg/day regimen (higher dose) is reserved for severe infections or areas with high pneumococcal resistance 1
- For mild URI as described in this case, the standard 45 mg/kg/day dose is appropriate 1, 3
Treatment duration:
- Continue treatment for 7-10 days for respiratory infections 1
- Minimum 48-72 hours beyond symptom resolution 3
Practical Administration
Liquid formulation options:
- Most amoxicillin suspensions come as 125 mg/5 mL or 250 mg/5 mL 3
- For 360 mg dose using 250 mg/5 mL concentration: give 7.2 mL per dose
- For 360 mg dose using 125 mg/5 mL concentration: give 14.4 mL per dose
Administration instructions:
- Give at the start of meals to minimize gastrointestinal intolerance 3
- Shake suspension well before each use 3
- Refrigeration is preferable but not required; discard after 14 days 3
Common Pitfalls to Avoid
Do not underdose: The older recommendation of 20-25 mg/kg/day is inadequate for current resistance patterns 4, 5. Research demonstrates that 40 mg/kg/day dosing is insufficient to eradicate resistant Streptococcus pneumoniae, particularly with viral coinfection 4.
Monitor for treatment failure: If no improvement occurs within 48-72 hours, reevaluation is necessary and consideration of step-up therapy to amoxicillin-clavulanate or alternative antibiotics may be needed 1, 6.
Expected Adverse Effects
The most common side effects include: