What is the recommended dosage of amoxicillin (amoxicillin) in mg/kg/day for an 11-week-old infant with otitis media?

Amoxicillin Dosing for Otitis Media in an 11-Week-Old Infant

For an 11-week-old infant with otitis media, the recommended dose of amoxicillin is 80-90 mg/kg/day divided into 2 doses. 1

First-Line Treatment Recommendation

• High-dose amoxicillin at 80-90 mg/kg/day given in 2 divided doses is the standard first-line therapy for acute otitis media in infants and children, including those as young as 11 weeks old 1

• This dosing regimen provides adequate middle ear fluid concentrations to cover Streptococcus pneumoniae (including intermediately resistant strains), Haemophilus influenzae, and Moraxella catarrhalis 1

Rationale for High-Dose Therapy

• High-dose amoxicillin (80-90 mg/kg/day) achieves middle ear fluid levels that exceed the minimum inhibitory concentration for intermediately resistant S. pneumoniae (penicillin MICs 0.12-1.0 μg/mL) and many highly resistant serotypes for a longer duration of the dosing interval 1

• Approximately 87% of S. pneumoniae isolates are susceptible to high-dose amoxicillin, compared to only 83% for standard-dose therapy 1

• The bacteriologic eradication rate for S. pneumoniae with high-dose amoxicillin reaches 92% 2

When to Consider Amoxicillin-Clavulanate Instead

Switch to high-dose amoxicillin-clavulanate (90 mg/kg/day of amoxicillin with 6.4 mg/kg/day of clavulanate in 2 divided doses) if: 1

• The infant received amoxicillin in the previous 30 days
• Concurrent purulent conjunctivitis is present (otitis-conjunctivitis syndrome)
• Coverage for β-lactamase-producing H. influenzae or M. catarrhalis is specifically desired

Treatment Duration and Monitoring

• Treat for 10 days in children under 2 years of age 1

• Clinical improvement should be evident within 48-72 hours; if no improvement occurs, reassess the diagnosis and consider treatment failure 3

• If treatment fails after 48-72 hours on amoxicillin, switch to amoxicillin-clavulanate (90 mg/kg/day) or consider ceftriaxone 1

Important Clinical Caveats

• The 14:1 ratio formulation of amoxicillin to clavulanate is preferred when using combination therapy, as it causes less diarrhea than other ratios 1

• Beta-lactamase-producing H. influenzae (present in 34-42% of cases) is the predominant pathogen in amoxicillin treatment failures 2

• Pain management should be addressed regardless of antibiotic choice 3