Amoxicillin Dosing for a 12-Year-Old with Ear Infection
For a 12-year-old weighing 67.9 kg with an ear infection (acute otitis media), prescribe high-dose amoxicillin 1,000 mg twice daily (total 2,000 mg/day) for 10 days. 1, 2, 3
Dose Calculation and Rationale
The American Academy of Pediatrics recommends high-dose amoxicillin at 80-90 mg/kg/day divided into two doses as first-line therapy for acute otitis media in children 1, 2, 3
For this 67.9 kg patient, the calculated dose would be:
- 80 mg/kg/day = 5,432 mg/day
- 90 mg/kg/day = 6,111 mg/day
However, the maximum single dose is 2,000 mg (1,000 mg twice daily), which is the practical upper limit for adolescents and adults 1
This patient should receive 1,000 mg twice daily (every 12 hours) for 10 days 4, 1, 3
Why High-Dose Therapy Matters
High-dose amoxicillin achieves middle ear fluid concentrations adequate to overcome resistance in Streptococcus pneumoniae with altered penicillin-binding proteins 1
The high-dose regimen provides effective coverage against drug-resistant S. pneumoniae while maintaining safety, low cost, and narrow microbiologic spectrum 2
Standard-dose amoxicillin (40-45 mg/kg/day) is inadequate to effectively eradicate resistant S. pneumoniae, particularly in areas with >10% penicillin-nonsusceptible strains 3, 5
Treatment Duration and Administration
Duration: 10 days of therapy is the standard recommendation from the American Academy of Pediatrics 1, 2, 3
Amoxicillin can be given without regard to meals, though administration with meals may improve gastrointestinal tolerability 1
The patient is considered no longer contagious after 24 hours of antibiotic therapy 4
When to Reassess and Switch Therapy
Reassess at 48-72 hours if symptoms worsen or fail to improve 1, 2, 3
If treatment fails (no improvement by 48-72 hours), switch to high-dose amoxicillin-clavulanate (90 mg/kg/day of amoxicillin component with 6.4 mg/kg/day clavulanate in 2 divided doses) 1, 3
The predominant pathogens isolated from children failing high-dose amoxicillin therapy are beta-lactamase-producing organisms (Haemophilus influenzae, Moraxella catarrhalis) 6
Important Clinical Considerations
Address pain management concurrently with antibiotic therapy, especially during the first 24 hours 1, 2
Consider amoxicillin-clavulanate as first-line instead if the patient:
Common Pitfalls to Avoid
Do not use standard-dose amoxicillin (40-45 mg/kg/day) in areas with >10% penicillin-nonsusceptible S. pneumoniae 3
Do not exceed the maximum single dose of 2,000 mg even when weight-based calculations suggest higher doses 1
Do not use amoxicillin-clavulanate as first-line therapy unless the child received amoxicillin in the previous 30 days or has otitis-conjunctivitis syndrome 1, 3