What is the recommended dose of amoxicillin (a penicillin antibiotic) for a pediatric patient with an ear infection, weighing between 10-25 kilograms (kg) and with no known allergies to penicillin?

Amoxicillin Dosing for Pediatric Ear Infections

For a pediatric patient weighing 10-25 kg with acute otitis media and no penicillin allergy, prescribe high-dose amoxicillin at 80-90 mg/kg/day divided into 2 doses (given every 12 hours) for 10 days. 1

Specific Weight-Based Calculations

For children in the 10-25 kg weight range:

• 10 kg child: 800-900 mg total daily dose = 400-450 mg twice daily 1, 2
• 15 kg child: 1200-1350 mg total daily dose = 600-675 mg twice daily 1, 2
• 20 kg child: 1600-1800 mg total daily dose = 800-900 mg twice daily 1, 2
• 25 kg child: 2000-2250 mg total daily dose = 1000-1125 mg twice daily 1, 2

Rationale for High-Dose Regimen

The high-dose amoxicillin recommendation (80-90 mg/kg/day) is specifically designed to achieve middle ear fluid concentrations that exceed the minimum inhibitory concentration for penicillin-resistant and intermediately-resistant Streptococcus pneumoniae. 1

• High-dose amoxicillin achieves middle ear fluid levels sufficient to eradicate approximately 87% of S. pneumoniae isolates, including intermediately resistant strains (penicillin MICs 0.12-1.0 μg/mL) and many highly resistant strains (penicillin MICs ≥2 μg/mL) 1
• Standard-dose amoxicillin (40 mg/kg/day) only covers approximately 83% of S. pneumoniae isolates and is inadequate for resistant strains 1, 3
• The twice-daily dosing schedule (every 12 hours) maintains therapeutic drug levels throughout the dosing interval while improving compliance compared to three-times-daily regimens 1, 2

Critical Treatment Duration

Complete the full 10-day course of amoxicillin regardless of symptom improvement. 1, 2

• The 10-day duration is mandatory for infections caused by Streptococcus pyogenes to prevent acute rheumatic fever 2
• Treatment should continue for a minimum of 48-72 hours beyond symptom resolution or evidence of bacterial eradication 2

When to Use Amoxicillin-Clavulanate Instead

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

• Child received amoxicillin within the previous 30 days
• Concurrent purulent conjunctivitis (otitis-conjunctivitis syndrome)
• Suspected β-lactamase-producing organisms (H. influenzae or M. catarrhalis)
• Treatment failure after 48-72 hours of standard amoxicillin therapy

Administration Guidelines

Administer amoxicillin at the start of a meal to minimize gastrointestinal intolerance. 2

• For oral suspension, shake the bottle vigorously before each dose 2
• The suspension can be placed directly on the child's tongue or mixed with formula, milk, fruit juice, or water and taken immediately 2
• Refrigeration of reconstituted suspension is preferable but not required; discard unused portion after 14 days 2

Common Pitfalls to Avoid

Do not use the outdated 40-45 mg/kg/day dosing regimen for acute otitis media. 1, 3

• Research demonstrates that standard-dose amoxicillin (40 mg/kg/day) is inadequate to effectively eradicate resistant S. pneumoniae, particularly during viral coinfection 3
• Middle ear fluid amoxicillin concentrations with standard dosing are insufficient, ranging from undetectable to subtherapeutic levels in many children 3
• Viral coinfection (present in approximately 20-40% of AOM cases) further reduces amoxicillin middle ear fluid penetration, making high-dose therapy even more critical 3

Reassessment Criteria

Reevaluate the child if no clinical improvement occurs within 48-72 hours of initiating therapy. 1, 2

• At this point, consider switching to high-dose amoxicillin-clavulanate (90/6.4 mg/kg/day) 1
• If second-line therapy fails, consider intramuscular ceftriaxone (50 mg/kg for 3 days) or tympanocentesis for culture-directed therapy 1

Penicillin Allergy Alternatives

For children with documented penicillin allergy: 1

• Non-anaphylactic reactions: Cefdinir (14 mg/kg/day), cefuroxime (30 mg/kg/day), or cefpodoxime (10 mg/kg/day) are appropriate alternatives with negligible cross-reactivity risk due to distinct chemical structures 1
• Type I hypersensitivity/anaphylaxis: Use azithromycin or clarithromycin, though these have inferior bacteriologic efficacy against resistant S. pneumoniae 1