Amoxicillin Dosing for Acute Otitis Media in a 9-Month-Old
For a 9-month-old infant weighing 9.75 kg with acute otitis media, prescribe high-dose amoxicillin 80-90 mg/kg/day divided into two doses every 12 hours, which equals 390-440 mg twice daily (780-880 mg total daily dose), for a 10-day course. 1, 2
Specific Dose Calculation
- Total daily dose: 80-90 mg/kg/day × 9.75 kg = 780-878 mg/day 1, 2
- Individual dose: 390-440 mg given every 12 hours 1, 2
- Duration: 10 days of therapy (full course required for children under 2 years) 3, 1, 2
Rationale for High-Dose Therapy
High-dose amoxicillin (80-90 mg/kg/day) is specifically indicated for this patient because:
- Age younger than 2 years (this infant is 9 months old) 1
- High-dose therapy achieves middle ear fluid concentrations adequate to overcome resistance in Streptococcus pneumoniae with altered penicillin-binding proteins 1
- The American Academy of Pediatrics recommends high-dose amoxicillin as first-line treatment for acute otitis media in children, particularly when drug-resistant Streptococcus pneumoniae is a concern 1, 4
Practical Administration
- Formulation: Use amoxicillin oral suspension 6 mg/mL concentration 3
- Volume per dose: For 400 mg dose, give approximately 67 mL of 6 mg/mL suspension 3
- Timing: Can be given without regard to meals, though administration with meals may improve gastrointestinal tolerability 1, 2
When to Reassess
Reassess the patient if symptoms worsen or fail to improve within 48-72 hours 1, 2:
- If treatment fails, 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, 2
- The predominant pathogens in amoxicillin failures are beta-lactamase-producing organisms, particularly Haemophilus influenzae 4
Pain Management
- Address pain management concurrently with antibiotic therapy, especially during the first 24 hours 1, 2
- Pain control should be provided regardless of antibiotic use 3
Critical Pitfalls to Avoid
- Do not use standard-dose amoxicillin (40-45 mg/kg/day) in children under 2 years old 1, 2
- Do not shorten the duration to less than 10 days for children younger than 2 years, as several studies favor standard 10-day therapy over shorter courses in this age group 3
- Do not use amoxicillin-clavulanate as first-line unless the child received amoxicillin in the previous 30 days or has concurrent purulent conjunctivitis (otitis-conjunctivitis syndrome) 1, 2