What is the recommended dose of amoxicillin (amoxicillin) for a 3-year-old pediatric patient with acute otitis media (ear infection)?

Amoxicillin Dosing for Acute Otitis Media in a 3-Year-Old

For a 3-year-old child with acute otitis media, prescribe high-dose amoxicillin at 80-90 mg/kg/day divided into 2 doses (given every 12 hours) for 5-7 days. 1

Dose Calculation and Practical Prescribing

• Calculate the total daily dose by multiplying the child's weight in kilograms by 80-90 mg, then divide by 2 to determine the individual dose given twice daily 1, 2
• For example, a 15 kg child would receive 1200-1350 mg/day total, administered as 600-675 mg twice daily 1, 2
• The high-dose regimen (80-90 mg/kg/day) is superior to standard-dose (40-45 mg/kg/day) because it achieves middle ear fluid concentrations adequate to overcome drug-resistant Streptococcus pneumoniae, which has altered penicillin-binding proteins 1, 3

Rationale for High-Dose Amoxicillin as First-Line

• Amoxicillin remains the first-line antibiotic for uncomplicated acute otitis media due to its effectiveness against common bacterial pathogens (S. pneumoniae, H. influenzae, M. catarrhalis), excellent safety profile, low cost, acceptable taste, and narrow microbiologic spectrum 1, 2
• High-dose amoxicillin achieves 92% eradication of S. pneumoniae (including penicillin-nonsusceptible strains with MIC ≤2.0 mcg/mL) and 84% eradication of beta-lactamase-negative H. influenzae by days 4-6 of therapy 4
• The standard dose of 40-45 mg/kg/day is inadequate, particularly when viral coinfection is present, as viral infection reduces middle ear fluid antibiotic penetration 3

Treatment Duration

• For children over 2 years of age with uncomplicated AOM, treat for 5-7 days 1, 2
• For children under 2 years or those with severe symptoms (high fever, intense earache, bilateral disease), extend treatment to 10 days 1
• Continue treatment for a minimum of 48-72 hours beyond symptom resolution 5

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, 14:1 ratio) in the following situations: 1, 6, 2

• The child received amoxicillin within the previous 30 days
• Concurrent purulent conjunctivitis is present (suggests H. influenzae infection)
• The child attends daycare
• The child is younger than 2 years with moderate-to-severe illness

The 14:1 ratio formulation (Augmentin ES-600) provides adequate coverage against beta-lactamase-producing H. influenzae and M. catarrhalis while minimizing diarrhea compared to higher clavulanate formulations 1, 6

Reassessment and Treatment Failure

• Reassess the patient at 48-72 hours if symptoms fail to improve 1, 2
• Treatment failure is defined as worsening condition, persistence of symptoms beyond 48 hours after starting antibiotics, or recurrence within 4 days of completing therapy 1, 2
• If initial amoxicillin fails, switch to high-dose amoxicillin-clavulanate 1, 6
• If amoxicillin-clavulanate fails, administer intramuscular ceftriaxone 50 mg/kg/day for 3 days 1, 6
• Beta-lactamase-producing H. influenzae is the predominant pathogen in treatment failures (present in 64% of bacteriologic failures) 4

Common Pitfalls to Avoid

• Do not use standard-dose amoxicillin (40-45 mg/kg/day) for initial treatment, as it provides inadequate middle ear fluid concentrations against resistant organisms 3, 4
• Avoid macrolides (azithromycin, clarithromycin) as first-line therapy—they achieve only 20-25% bacteriologic efficacy against major AOM pathogens and are significantly inferior to high-dose amoxicillin-clavulanate (96% vs lower eradication rates) 6
• Do not use the 7:1 amoxicillin-clavulanate ratio formulations (higher clavulanate content), as they significantly increase diarrhea risk without improving efficacy 6
• Ensure the medication is taken at the start of meals to minimize gastrointestinal intolerance 5

Pain Management

• Address pain management concurrently with antibiotic therapy during the first 24 hours using acetaminophen or ibuprofen 1, 2