Amoxicillin Dosing for Otitis Media in a 12 kg Child
For a 12 kg child with acute otitis media, administer amoxicillin 80-90 mg/kg/day divided into 2 doses, which equals 480-540 mg twice daily (approximately 960-1080 mg total daily dose). 1, 2
Specific Dose Calculation
- Total daily dose: 80-90 mg/kg/day × 12 kg = 960-1080 mg/day 1
- Divided dosing: Give 480-540 mg twice daily (every 12 hours) 1, 2
- Treatment duration: 10 days for children under 2 years of age 1, 2
Rationale for High-Dose Therapy
- High-dose amoxicillin achieves middle ear fluid concentrations that exceed the minimum inhibitory concentration for intermediately resistant Streptococcus pneumoniae and covers the majority of common otitis media pathogens 1, 2
- Approximately 87% of S. pneumoniae isolates are susceptible to high-dose amoxicillin compared to only 83% with standard dosing 1
- This dosing provides adequate coverage against Haemophilus influenzae and Moraxella catarrhalis as well 1
When to Switch to Amoxicillin-Clavulanate
Use high-dose amoxicillin-clavulanate (90 mg/kg/day of amoxicillin component with 6.4 mg/kg/day clavulanate in 2 divided doses) instead of amoxicillin alone if: 1, 2
- The child received amoxicillin in the previous 30 days 1
- Concurrent purulent conjunctivitis is present 1
- Coverage for β-lactamase-producing H. influenzae or M. catarrhalis is specifically desired 1
The 14:1 ratio formulation (amoxicillin to clavulanate) is preferred as it causes less diarrhea than other preparations 1, 3
Monitoring and Treatment Failure
- Assess clinical response at 48-72 hours: The child should show improvement in fever, pain, and irritability 2, 3
- If no improvement after 48-72 hours: Switch to high-dose amoxicillin-clavulanate or consider ceftriaxone (50 mg/kg IM/IV for 1-3 days) 1, 2
- Beta-lactamase-producing H. influenzae is the most common cause of amoxicillin treatment failure, occurring in approximately 62% of persistent infections 4
Important Clinical Caveats
- Pain management is essential regardless of antibiotic choice and should be addressed at the initial visit 2, 3
- The current standard-dose amoxicillin (40 mg/kg/day) is inadequate to effectively eradicate resistant S. pneumoniae, particularly during viral coinfection 5
- Research shows that middle ear fluid amoxicillin concentrations are lowest in virus-infected children, supporting the need for higher dosing 5
- For penicillin-allergic children, cefdinir (14 mg/kg/day), cefuroxime (30 mg/kg/day), or cefpodoxime (10 mg/kg/day) are appropriate alternatives 1, 3