High-Dose Amoxicillin-Clavulanate at 90 mg/kg/day (Amoxicillin Component) in Two Divided Doses
For a 19-month-old child with acute otitis media, prescribe high-dose amoxicillin-clavulanate at 90 mg/kg/day of the amoxicillin component with 6.4 mg/kg/day of clavulanate, divided into two doses every 12 hours, using the 14:1 ratio formulation (600 mg amoxicillin/42.9 mg clavulanate per 5 mL suspension). 1, 2, 3
Why High-Dose Amoxicillin-Clavulanate Is First-Line for This Age Group
Children under 2 years with acute otitis media require antibiotic therapy and specifically warrant high-dose amoxicillin-clavulanate as first-line treatment because this age group has the highest risk of resistant organisms, treatment failure, and complications. 1, 2, 3
The high-dose regimen achieves middle ear fluid concentrations that overcome penicillin-resistant Streptococcus pneumoniae (MIC 2–4 µg/mL), which is the predominant bacterial pathogen in children under 2 years, with clinical response rates of 76–95% and bacterial eradication rates of 96–98%. 1, 4
The 14:1 ratio formulation (90 mg/kg/day amoxicillin with 6.4 mg/kg/day clavulanate) causes significantly less diarrhea than older formulations while maintaining full efficacy against β-lactamase-producing Haemophilus influenzae and Moraxella catarrhalis. 1, 2, 5
Specific Dosing Calculation
Calculate the total daily amoxicillin dose by multiplying the child's weight in kilograms by 90 mg/kg, then divide by 2 to get each individual dose given every 12 hours. 1, 3
For example, a 19-month-old weighing 11 kg would receive: 11 kg × 90 mg/kg = 990 mg total daily dose, administered as 495 mg (approximately 4.1 mL of the 600 mg/5 mL suspension) every 12 hours. 1, 6
The FDA-approved formulation for this age group is the oral suspension providing 600 mg amoxicillin/42.9 mg clavulanate per 5 mL, which delivers the required 14:1 ratio. 6, 5
Treatment Duration and Expected Response
Treat for 10 days in all children under 2 years of age with acute otitis media. 1, 2, 3
Clinical improvement (reduced pain, fever, and irritability) should be evident within 48–72 hours of starting therapy. 1, 3
If no improvement or worsening occurs after 48–72 hours, reassess the diagnosis and switch to intramuscular or intravenous ceftriaxone 50 mg/kg for three days. 2, 3
Why Not Start with Amoxicillin Alone
While high-dose amoxicillin (80–90 mg/kg/day) is recommended as first-line for older children with uncomplicated acute otitis media, children under 2 years have multiple risk factors that favor starting with amoxicillin-clavulanate: 2, 3
Age under 2 years itself is a risk factor for resistant organisms and treatment failure. 1, 2
This age group has higher rates of daycare attendance (38% in clinical trials), recent antibiotic exposure (50% within 3 months), and bilateral disease (60%), all of which increase the likelihood of β-lactamase-producing organisms. 4
Starting with amoxicillin-clavulanate avoids the need to switch antibiotics after 48–72 hours of treatment failure, reducing both symptom duration and parental anxiety. 2, 3
Common Pitfalls to Avoid
Do not use the 125 mg/31.25 mg per 5 mL suspension for high-dose therapy—this formulation provides only 25 mg/kg/day when dosed appropriately and will result in treatment failure. 1, 6
Verify you are prescribing the 600 mg/5 mL (ES-600) formulation, which is the only suspension concentration that delivers 90 mg/kg/day in practical volumes for young children. 1, 5
Do not substitute two 250 mg tablets for one 500 mg tablet or mix formulations, as the clavulanate ratios differ and this will result in either underdosing amoxicillin or overdosing clavulanate (causing diarrhea). 6
The maximum single dose is 2,000 mg of amoxicillin regardless of weight, though this ceiling is rarely relevant in a 19-month-old. 1, 6
Adverse Effects and Counseling Points
Diarrhea occurs in approximately 17–26% of children on high-dose amoxicillin-clavulanate, compared to 14–15% on placebo, but the 14:1 ratio formulation has significantly lower rates than older 7:1 or 4:1 formulations. 1, 7
Diaper dermatitis occurs in 21–51% of treated children but is generally mild and manageable with barrier creams. 1, 7
Counsel parents that gastrointestinal side effects do not indicate treatment failure and that stopping antibiotics prematurely increases the risk of resistant organisms and recurrent infection. 1, 2