Amoxicillin Dosing for Acute Otitis Media in a 7-Year-Old Weighing 21.68 kg
Prescribe high-dose amoxicillin at 80–90 mg/kg/day divided into two doses for 10 days, which equals 1,734–1,951 mg total daily (approximately 875–975 mg twice daily) for this child. 1
Specific Dose Calculation
For a 21.68 kg child, calculate 80–90 mg/kg/day:
- Lower range: 21.68 kg × 80 mg/kg = 1,734 mg/day
- Upper range: 21.68 kg × 90 mg/kg = 1,951 mg/day 1
Divide into two equal doses given 12 hours apart:
- Practical dosing: 875 mg twice daily (1,750 mg/day total) falls within the recommended range and uses standard tablet/suspension strengths 1
Treatment Duration
- Treat for 10 days in children younger than 6 years with any severity of acute otitis media. 2
- For children 6 years and older with mild-to-moderate symptoms, a 5–7 day course may be sufficient, but given this child is 7 years old and severity is not specified, the 10-day course remains the safest recommendation 2
Rationale for High-Dose Therapy
- High-dose amoxicillin (80–90 mg/kg/day) achieves middle ear fluid concentrations that cover approximately 87% of Streptococcus pneumoniae isolates, including intermediately resistant strains, compared to only 83% coverage with standard dosing. 1
- This regimen provides adequate coverage against the three principal pathogens: S. pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis 1
- High-dose therapy is specifically recommended by the American Academy of Pediatrics to overcome drug-resistant S. pneumoniae 2
When to Switch to Amoxicillin-Clavulanate Instead
Use high-dose amoxicillin-clavulanate (90 mg/kg/day amoxicillin + 6.4 mg/kg/day clavulanate in a 14:1 ratio, divided twice daily) as first-line therapy if any of the following apply:
- The child received amoxicillin within the prior 30 days 1, 2
- Concurrent purulent conjunctivitis is present 1, 2
- The child attends daycare (increased risk of β-lactamase-producing H. influenzae) 2
Management of Treatment Failure
Reassess within 48–72 hours; if no clinical improvement or worsening symptoms occur, first confirm the diagnosis of acute otitis media. 1, 2
If the child fails to improve on amoxicillin alone, switch to high-dose amoxicillin-clavulanate (90 mg/kg/day amoxicillin component + 6.4 mg/kg/day clavulanate). 1, 2
If failure persists after amoxicillin-clavulanate, administer intramuscular ceftriaxone 50 mg/kg/day for 3 days. 1, 2
The predominant pathogens causing treatment failure are β-lactamase-producing organisms, particularly H. influenzae. 3
Important Clinical Caveats
The 14:1 amoxicillin-clavulanate formulation causes significantly less diarrhea than older 7:1 formulations while maintaining efficacy against β-lactamase-producing organisms. 1
Address pain management regardless of antibiotic choice. 2
Avoid trimethoprim-sulfamethoxazole and erythromycin-sulfisoxazole for treatment failures due to high pneumococcal resistance. 2
Persistent middle ear effusion without acute symptoms (60–70% at 2 weeks, 40% at 1 month) is common after treatment and does not require additional antibiotics. 2