Amoxicillin Dosing for Otitis Media
High-dose amoxicillin at 80-90 mg/kg/day divided into 2 doses is the recommended first-line treatment for acute otitis media in children. 1, 2, 3
Standard Dosing Regimen
- Administer 80-90 mg/kg/day divided into 2 daily doses for most pediatric patients with acute otitis media 1, 2, 3
- This high-dose regimen achieves middle ear fluid concentrations that exceed the minimum inhibitory concentration (MIC) for intermediately resistant Streptococcus pneumoniae (penicillin MICs 0.12-1.0 μg/mL) and many highly resistant serotypes (penicillin MICs ≥2 μg/mL) for a longer duration of the dosing interval 4, 2
- Approximately 87% of S. pneumoniae isolates are susceptible to high-dose amoxicillin, compared to only 83% for standard-dose therapy 4, 2
- The twice-daily dosing schedule is as effective as three-times-daily administration and improves adherence by reducing family-perceived problems with dosing schedules 5
Treatment Duration by Age
- Children under 2 years of age: treat for 10 days 2
- Children 2-5 years with severe symptoms: treat for 10 days 3
- Children ≥6 years or those 2-5 years with mild symptoms: treat for 5-7 days 3
When to Use Amoxicillin-Clavulanate Instead
Switch to high-dose amoxicillin-clavulanate (90 mg/kg/day of amoxicillin with 6.4 mg/kg/day of clavulanate in a 14:1 ratio, divided into 2 doses) in these specific situations: 4, 1, 2
- Child received amoxicillin in the previous 30 days
- Concurrent purulent conjunctivitis is present
- Coverage for β-lactamase-producing Haemophilus influenzae or Moraxella catarrhalis is specifically desired
- The 14:1 ratio formulation causes less diarrhea than other amoxicillin-clavulanate preparations 4, 2
Management of Treatment Failure
- Reassess at 48-72 hours if symptoms fail to improve 1, 3
- If no improvement occurs by 48-72 hours, switch to amoxicillin-clavulanate (90 mg/kg/day of amoxicillin with 6.4 mg/kg/day of clavulanate) 1, 3
- Alternatively, administer ceftriaxone 50 mg/kg IM or IV for 3 days 1
- Beta-lactamase-producing H. influenzae is the predominant pathogen in children failing high-dose amoxicillin therapy, with 62% eradication rate for beta-lactamase-positive strains compared to 84% for beta-lactamase-negative strains 6
Important Clinical Caveats
- High-dose amoxicillin is preferred due to its safety, low cost, acceptable taste, and narrow microbiologic spectrum 1, 3
- Pain management should be addressed concurrently during the first 24 hours regardless of antibiotic choice 2, 3
- For children weighing >20 kg, physicians often prescribe lower-than-recommended doses; however, the full weight-based dose should be prescribed unless it exceeds the standard adult maximum of 1500 mg/day 7
- In communities with low prevalence of highly resistant S. pneumoniae (<5%), standard-dose amoxicillin may be considered, though current guidelines universally recommend high-dose therapy 8