What is the maximum amoxicillin dose per dose and per day for a child with acute otitis media when prescribing 90 mg/kg/day?

Maximum Amoxicillin Dose for Pediatric Acute Otitis Media at 90 mg/kg/day

When prescribing amoxicillin at 90 mg/kg/day for acute otitis media in children, the maximum single dose should not exceed 2000 mg per dose, regardless of the child's weight. 1

Dosing Framework

Standard High-Dose Regimen

• The recommended dose is 80-90 mg/kg/day divided into 2 doses (given every 12 hours), which serves as first-line therapy for uncomplicated acute otitis media 1, 2, 3, 4, 5
• This high-dose regimen achieves middle ear fluid concentrations exceeding the minimum inhibitory concentration for approximately 87% of Streptococcus pneumoniae isolates, including intermediately resistant strains 1

Maximum Dose Caps

• The absolute maximum single dose is 2000 mg per dose, meaning no individual dose should exceed this amount even if weight-based calculations suggest a higher dose 1
• For practical purposes, this translates to a maximum total daily dose of 4000 mg/day (2000 mg twice daily) 6, 2

Clinical Application Example

For a child weighing more than 44 kg (approximately 97 pounds):

• Weight-based calculation: 90 mg/kg/day × 44 kg = 3960 mg/day ÷ 2 doses = 1980 mg per dose
• This would be acceptable as it remains under the 2000 mg per dose maximum 1

For a child weighing 50 kg (110 pounds):

• Weight-based calculation: 90 mg/kg/day × 50 kg = 4500 mg/day ÷ 2 doses = 2250 mg per dose
• Cap this at 2000 mg per dose (4000 mg/day total), not the calculated 2250 mg 1

Rationale for High-Dose Therapy

Pharmacokinetic Justification

• Standard dosing of 40 mg/kg/day is inadequate to effectively eradicate resistant Streptococcus pneumoniae, particularly during viral coinfection 7
• Research demonstrates that amoxicillin middle ear fluid penetration is lower in children with viral coinfection, further supporting the need for high-dose therapy 7
• The 75-90 mg/kg/day dosing range was specifically recommended based on pharmacokinetic studies showing improved bacterial eradication rates 7

Efficacy Data

• High-dose amoxicillin achieves 82% bacteriologic eradication compared to lower rates with inadequate dosing 2
• The American Academy of Pediatrics guidelines emphasize that treatment failures with inadequate dosing are predominantly due to beta-lactamase-producing Haemophilus influenzae and resistant pneumococcal strains 2

Common Pitfalls and Caveats

Weight-Related Prescribing Errors

• Primary care physicians frequently prescribe significantly lower-than-recommended doses in older children and those in higher weight categories 8
• There is considerable variation among experts regarding maximum dose specifications, with some capping at the standard adult dose of 1500 mg/day despite guideline recommendations 8
• This practice is inappropriate and may lead to treatment failure—always use the 2000 mg per dose maximum, not the 1500 mg/day adult standard dose 1, 8

When to Switch to Amoxicillin-Clavulanate

Switch to high-dose amoxicillin-clavulanate (90 mg/kg/day of amoxicillin component with 6.4 mg/kg/day clavulanate) in the following situations:

• Amoxicillin use within the previous 30 days 1, 2, 3, 4
• Concurrent purulent conjunctivitis 1, 2, 3, 4
• Treatment failure after 48-72 hours of amoxicillin therapy 1, 2, 3
• Need for coverage against beta-lactamase-producing H. influenzae or Moraxella catarrhalis 1, 2

Treatment Monitoring

• Reassess at 48-72 hours if symptoms fail to improve or worsen 2, 3, 4, 5
• Clinical improvement should be evident within this timeframe; lack of response warrants switching to alternative therapy 1, 2
• Pain management should be addressed concurrently during the first 24 hours 3

Duration Considerations

• Standard treatment duration is 5-10 days depending on age and severity 2, 3
• Children over 2 years with uncomplicated acute otitis media may be treated for 5 days 3