What is the recommended dosage of amoxicillin for a child with a severe acute respiratory infection at 80-90 mg/kg/day?

Amoxicillin Dosing for Severe Acute Respiratory Infections in Children

For children with severe acute respiratory infections, amoxicillin at a dose of 80-90 mg/kg/day is appropriate as a high-dose regimen, particularly when treating suspected resistant pathogens or as second-line therapy after treatment failure.

Dosing Recommendations Based on Infection Severity

• For severe acute respiratory infections, high-dose amoxicillin at 80-90 mg/kg/day is recommended as second-line therapy after treatment failure with standard dosing 1
• For initial treatment of presumed bacterial pneumonia in outpatient settings, amoxicillin at 90 mg/kg/day in 2 doses is recommended for children of all ages 1
• For Haemophilus influenzae infections (if β-lactamase negative), amoxicillin at 75-100 mg/kg/day in 3 doses is appropriate 1
• For pneumococcal infections with high penicillin MICs (≥4.0 μg/mL), higher doses of amoxicillin (300-400 mg/kg/day) may be needed for parenteral therapy 1

Clinical Scenarios for High-Dose Amoxicillin (80-90 mg/kg/day)

Second-Line Therapy

• Children who fail initial treatment with standard-dose amoxicillin should receive high-dose amoxicillin with clavulanic acid (80-90 mg/kg/day of amoxicillin component) 1
• This higher dosing is specifically intended to provide coverage for major pathogens likely to cause severe disease that were not adequately treated with first-line therapy 1

Areas with High Pneumococcal Resistance

• In regions with significant penicillin resistance among pneumococcal strains, higher dosing of amoxicillin (90 mg/kg/day) is warranted from the outset 2
• This higher dosing helps overcome resistance by achieving adequate drug concentrations in the respiratory tract 3

Administration Considerations

• The total daily dose should be divided into 2-3 doses per day 1, 4
• For twice-daily dosing, each dose would be 40-45 mg/kg 4
• For three-times-daily dosing, each dose would be approximately 27-30 mg/kg 4
• Administration should occur at the start of a meal to minimize gastrointestinal intolerance 4

Treatment Duration

• For most respiratory infections, treatment should continue for 5-7 days 1, 5
• For infections caused by Streptococcus pyogenes, treatment should continue for at least 10 days to prevent acute rheumatic fever 4
• Treatment should generally continue for 48-72 hours beyond the time that the patient becomes asymptomatic 4

Special Considerations

• For children with viral co-infections, higher dosing may be particularly important as viral infections can reduce amoxicillin penetration into middle ear fluid and potentially other respiratory sites 3
• For children less than 3 months of age, dosing should not exceed 30 mg/kg/day due to incompletely developed renal function 4
• For children with severe renal impairment (GFR <30 mL/min), dose adjustment is necessary 4

Monitoring and Follow-up

• Children on adequate therapy should demonstrate clinical improvement within 48-72 hours 1
• If a child's condition deteriorates or shows no improvement within this timeframe, further investigation should be performed 1
• Common adverse effects to monitor include gastrointestinal disturbances (diarrhea, nausea, vomiting) and hypersensitivity reactions 2

The 80-90 mg/kg/day dosing represents a high-dose strategy that balances efficacy against resistant pathogens with safety considerations in pediatric patients with severe respiratory infections.