Amoxicillin Dosing for Acute Otitis Media in a 3-Year-Old Weighing 13.7kg
For a 3-year-old child weighing 13.7 kg with an ear infection, prescribe high-dose amoxicillin at 80-90 mg/kg/day divided into two daily doses, which equals approximately 550-615 mg twice daily (or practically, 600 mg twice daily) for 10 days. 1, 2
Dose Calculation
- Total daily dose: 80-90 mg/kg/day × 13.7 kg = 1,096-1,233 mg/day 1, 2
- Divided dosing: Give approximately 550-615 mg twice daily (every 12 hours) 1, 2, 3
- Practical prescription: 600 mg twice daily is a reasonable approximation (approximately 88 mg/kg/day) 2
- Alternatively, you could prescribe 550 mg twice daily using oral suspension 3
Rationale for High-Dose Therapy
High-dose amoxicillin (80-90 mg/kg/day) is the first-line treatment because it provides effective coverage against drug-resistant Streptococcus pneumoniae while maintaining safety, acceptable taste, and narrow microbiologic spectrum. 1, 2
- The most common bacterial pathogens in acute otitis media are S. pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis 1, 2
- High-dose amoxicillin achieves middle ear fluid concentrations sufficient to eradicate resistant pneumococcal strains 4, 5
- Standard-dose amoxicillin (40-45 mg/kg/day) is inadequate for resistant S. pneumoniae, particularly during viral coinfection 4
Treatment Duration
- Treat for 10 days in children under 6 years of age with acute otitis media 1
- Some guidelines suggest 5-7 days may be sufficient for children over 2 years with uncomplicated cases, but 10 days remains standard for this age group 2
Administration Instructions
- Give at the start of meals to minimize gastrointestinal intolerance 3
- Shake oral suspension well before each use 3
- Reconstituted suspension remains stable for 14 days (refrigeration preferred but not required) 3
When to Switch to Alternative Therapy
Consider amoxicillin-clavulanate (90 mg/kg/day of amoxicillin component) instead of amoxicillin alone if: 1, 2
- The child received amoxicillin in the previous 30 days 1, 2
- Concurrent purulent conjunctivitis is present 1, 2
- History of recurrent AOM unresponsive to amoxicillin 1
Reassessment Criteria
Reassess the patient at 48-72 hours if symptoms fail to improve or worsen at any time. 1, 2
- Treatment failure indicators include: persistent fever, worsening ear pain, or no improvement in symptoms after 48-72 hours 1, 2
- If treatment fails, switch to amoxicillin-clavulanate or consider intramuscular ceftriaxone 1, 2
- Beta-lactamase-producing H. influenzae is the most common cause of amoxicillin treatment failure 5
Pain Management
Address pain management concurrently during the first 24 hours with acetaminophen or ibuprofen as this is a critical component of AOM treatment. 1, 2
Important Caveats
- Viral coinfection reduces amoxicillin efficacy: Middle ear fluid amoxicillin concentrations are lower in children with concurrent viral infections 4
- Beta-lactamase producers: Approximately 34% of H. influenzae strains produce beta-lactamase and may not respond to amoxicillin alone 5
- Bacteriologic failure rate: Even with high-dose amoxicillin, approximately 28% of patients may have bacteriologic failure by days 4-6, though clinical efficacy remains good at 94% 5
- Penicillin allergy: If the child has a true penicillin allergy, alternative agents are needed; this scenario may require specialist consultation 1