What is the appropriate Augmentin (amoxicillin/clavulanate) dose per administration for an 18‑month‑old child weighing 23 lb (≈10.5 kg) with acute bilateral otitis media?

Augmentin Dosing for 18-Month-Old with Bilateral Otitis Media

For this 18-month-old child weighing 23 lb (10.5 kg) with bilateral acute otitis media, prescribe high-dose amoxicillin-clavulanate 90 mg/kg/day of the amoxicillin component, which equals approximately 945 mg per day divided into two doses of 472.5 mg every 12 hours for 10 days. 1

Why High-Dose Augmentin Is Required

Bilateral otitis media in a child under 2 years mandates immediate antibiotic therapy—not observation—and specifically warrants the high-dose amoxicillin-clavulanate formulation. 1 The bilateral presentation in this age group carries higher risk for treatment failure and complications. 1

Key Indications for High-Dose Augmentin Over Plain Amoxicillin

Use amoxicillin-clavulanate (rather than amoxicillin alone) as first-line when any of these factors are present:

• Age < 2 years with bilateral AOM (this patient meets both criteria) 1
• Recent amoxicillin use within the past 30 days 1, 2
• Concurrent purulent conjunctivitis suggesting Haemophilus influenzae 1, 2
• Daycare attendance or geographic area with high prevalence of β-lactamase-producing organisms 2

Exact Dosing Calculation

Weight conversion: 23 lb ÷ 2.2 = 10.45 kg (round to 10.5 kg) 1

Dose calculation: 90 mg/kg/day × 10.5 kg = 945 mg total daily dose 1, 2

Per-dose amount: 945 mg ÷ 2 = 472.5 mg every 12 hours 1, 2

Practical Formulation Selection

The high-dose formulation provides a 14:1 ratio of amoxicillin to clavulanate (90 mg/kg amoxicillin with 6.4 mg/kg clavulanate), which minimizes diarrhea compared to older 7:1 formulations while maintaining efficacy. 1, 2

Use the 600 mg/42.9 mg per 5 mL suspension (Augmentin ES-600), which is specifically designed for this high-dose regimen. 3 For this child, prescribe approximately 4 mL twice daily to deliver ~480 mg per dose. 3

Alternatively, if only standard formulations are available, you can use the 400 mg/57 mg per 5 mL suspension at approximately 6 mL twice daily, though this provides a less favorable amoxicillin-to-clavulanate ratio. 2

Treatment Duration and Monitoring

Duration: Full 10-day course is mandatory for children under 2 years, regardless of symptom severity. 1 Shorter courses (5–7 days) are only appropriate for children ≥6 years with mild-moderate disease. 1

Reassessment protocol: Evaluate at 48–72 hours. 1 If symptoms worsen or fail to improve:

• Confirm the diagnosis with repeat pneumatic otoscopy 1
• Switch to intramuscular ceftriaxone 50 mg/kg once daily for 3 consecutive days (a 3-day course is superior to single-dose) 1

Pain Management (Critical First Step)

Initiate weight-based acetaminophen or ibuprofen immediately, before or concurrent with antibiotics. 1 Analgesics provide symptomatic relief within 24 hours, whereas antibiotics provide zero pain relief in the first 24 hours—and 30% of children under 2 still have pain after 3–7 days of antibiotic therapy. 1

Microbiologic Rationale

High-dose amoxicillin-clavulanate achieves middle ear fluid concentrations that overcome:

• Penicillin-resistant Streptococcus pneumoniae with MICs up to 2–4 mg/L 1, 3, 4
• β-lactamase-producing Haemophilus influenzae (present in 34% of isolates) 5
• β-lactamase-producing Moraxella catarrhalis 1, 4

The FDA-approved formulation demonstrated 98.4% eradication of S. pneumoniae (including 85.7% of strains with penicillin MIC = 4 mg/L) and 92.6% eradication of H. influenzae in clinical trials. 3

Common Pitfalls to Avoid

• Do not use standard-dose amoxicillin (40–45 mg/kg/day) in children under 2 with bilateral AOM—this is inadequate for resistant organisms. 1, 6
• Do not use azithromycin or other macrolides as first-line—pneumococcal macrolide resistance exceeds 40% in the United States, with bacterial failure rates of 20–25%. 1
• Do not use trimethoprim-sulfamethoxazole or erythromycin-sulfisoxazole for treatment failures—resistance is substantial. 1
• Verify the suspension concentration before dispensing to avoid dosing errors (600/42.9 vs. 400/57 formulations have different volumes per dose). 2

Expected Post-Treatment Course

Middle ear effusion persists in 60–70% of children at 2 weeks after successful therapy, declining to ~40% at 1 month and 10–25% at 3 months. 1 This asymptomatic post-AOM effusion (otitis media with effusion) requires monitoring but not additional antibiotics unless it persists >3 months with documented hearing loss. 1

Adverse Effects

Diarrhea occurs in approximately 25% of patients (vs. 15% with placebo), and diaper dermatitis in 51% (vs. 35% with placebo). 2 Twice-daily dosing causes significantly less diarrhea than three-times-daily dosing while providing equivalent efficacy. 1, 7 Administer with meals to improve gastrointestinal tolerability. 6