What is the recommended dosage of amoxicillin (400 mg/5 mL concentration) for a 2-year-old female patient weighing 16.15 kg with otitis media?

Amoxicillin-Clavulanate 400/5 Dosing for Otitis Media in a 2-Year-Old

For a 2-year-old weighing 16.15 kg with otitis media using the 400 mg/5 mL concentration, administer 9.1 mL (approximately 9 mL) twice daily for 10 days, providing the recommended high-dose regimen of 90 mg/kg/day of the amoxicillin component. 1, 2

Dose Calculation

• The calculation is: 16.15 kg × 90 mg/kg/day = 1,453.5 mg total daily dose, divided into 2 doses = 726.75 mg per dose 1, 2
• Using the 400 mg/5 mL suspension: (726.75 mg ÷ 400 mg) × 5 mL = 9.08 mL per dose, rounded to 9 mL for practical administration 3
• This provides approximately 720 mg of amoxicillin per dose (88.9 mg/kg/day), which falls within the recommended 80-90 mg/kg/day range 4, 1

Rationale for High-Dose Regimen

This patient requires high-dose therapy because she is under 2 years of age, which is a specific indication for the 90 mg/kg/day regimen. 4, 1

• Children under 2 years with acute otitis media have increased risk for infection with penicillin-resistant Streptococcus pneumoniae and require high-dose amoxicillin-clavulanate as first-line therapy 4, 1
• The high-dose formulation (90 mg/kg/day with 6.4 mg/kg/day clavulanate) achieves middle ear fluid concentrations adequate to overcome penicillin-resistant S. pneumoniae with MICs of 2-4 mg/L 1
• The 400 mg/5 mL concentration provides the optimal 14:1 ratio of amoxicillin to clavulanate, which causes less diarrhea than other formulations while maintaining efficacy 1

Treatment Duration and Monitoring

• Complete the full 10-day course of therapy, as this is the recommended duration for acute otitis media in children under 2 years 4, 1, 3
• Clinical improvement should be evident within 48-72 hours of starting therapy 4, 1
• If symptoms worsen or fail to improve within 48-72 hours, reassess the patient and consider switching to an alternative antibiotic with broader coverage 4

Administration Instructions

• Administer 9 mL of the 400 mg/5 mL suspension twice daily (every 12 hours) 3
• The medication can be given without regard to meals, though administration with food may improve gastrointestinal tolerability 2
• Shake the suspension well before each dose to ensure proper concentration 3

Common Pitfalls to Avoid

• Do not use standard-dose amoxicillin (40-45 mg/kg/day) for children under 2 years with otitis media, as this leads to treatment failure with resistant organisms 1
• Do not substitute the 250 mg/5 mL suspension for the 400 mg/5 mL suspension without recalculating the volume, as this would result in underdosing 3
• The 400 mg/5 mL formulation is specifically designed for twice-daily dosing and should not be given three times daily 3

Expected Adverse Effects

• Diarrhea occurs in approximately 14% of children receiving the twice-daily high-dose regimen, which is significantly lower than the 34% incidence with three-times-daily dosing 3
• Diaper dermatitis may occur in up to 51% of treated children 1
• These adverse effects are generally mild and do not require discontinuation of therapy 1, 3