What is the recommended dose of amoxicillin (amoxicillin) for a 2-year-old female with acute otitis media (AOM) weighing 31 pounds?

Amoxicillin Dosing for AOM in a 2-Year-Old

For a 2-year-old female weighing 31 pounds (14 kg) with acute otitis media, prescribe high-dose amoxicillin at 80-90 mg/kg/day divided into two doses, which equals 560-630 mg twice daily for 10 days. 1

Dose Calculation

• Weight conversion: 31 pounds = 14 kg
• Recommended dosing: 80-90 mg/kg/day of amoxicillin 2, 1
• Daily total: 14 kg × 80-90 mg/kg = 1,120-1,260 mg/day
• Per dose (twice daily): 560-630 mg given every 12 hours 1

Formulation Selection

• Use amoxicillin suspension (typically 400 mg/5 mL or 250 mg/5 mL formulations) 2
• Practical dosing: Give approximately 7-8 mL of 400 mg/5 mL suspension twice daily, or 11-13 mL of 250 mg/5 mL suspension twice daily 3
• The twice-daily regimen is preferred over three-times-daily dosing as it significantly reduces diarrhea (14% vs 34%) while maintaining equivalent efficacy 3, 4

Treatment Duration

• Treat for 10 days in children under 2 years of age 1, 3
• This duration is specifically studied and recommended for acute otitis media in this age group 3

Rationale for High-Dose Therapy

• High-dose amoxicillin achieves middle ear fluid concentrations that exceed the minimum inhibitory concentration for intermediately resistant Streptococcus pneumoniae 1
• Approximately 87% of S. pneumoniae isolates are susceptible to high-dose amoxicillin, compared to only 83% for standard-dose therapy 1
• Standard dosing of 40 mg/kg/day is inadequate to effectively eradicate resistant S. pneumoniae, particularly during viral coinfection 5

When to Switch to Amoxicillin-Clavulanate

Consider switching to high-dose amoxicillin-clavulanate (90 mg/kg/day of amoxicillin component) if: 2, 1

• The child received amoxicillin in the previous 30 days
• Concurrent purulent conjunctivitis is present
• The child attends daycare
• No clinical improvement occurs within 48-72 hours of starting amoxicillin 1

Monitoring and Follow-Up

• Expect clinical improvement within 48-72 hours of starting therapy 2, 1
• If no improvement occurs within this timeframe, reassess the diagnosis and consider treatment failure requiring a switch to amoxicillin-clavulanate or ceftriaxone 1
• Address pain management regardless of antibiotic choice 2, 1

Important Clinical Caveat

• The predominant pathogens causing failure of high-dose amoxicillin are beta-lactamase-producing organisms, particularly Haemophilus influenzae 6
• Despite this, high-dose amoxicillin remains the appropriate first-line choice due to its overall good clinical efficacy (82% bacteriologic eradication rate), with beta-lactamase-stable drugs reserved for treatment failures 6