Amoxicillin Dosing for 58-Pound Patient with Otitis Media
For a 58-pound (26.3 kg) patient with otitis media, prescribe amoxicillin 80-90 mg/kg/day divided into two doses, which equals approximately 1050-1185 mg twice daily (total daily dose 2100-2370 mg), given for 10 days. 1
Dose Calculation
- Patient weight: 58 lbs = 26.3 kg
- High-dose amoxicillin: 80-90 mg/kg/day 1
- Total daily dose: 2100-2370 mg/day (26.3 kg × 80-90 mg/kg) 1
- Divided dosing: Give 1050-1185 mg twice daily (every 12 hours) 1
- Practical prescription: Amoxicillin 1100 mg twice daily for 10 days
Rationale for High-Dose Therapy
- High-dose amoxicillin (80-90 mg/kg/day) is specifically recommended by the American Academy of Pediatrics and American Academy of Family Physicians for otitis media to achieve adequate middle ear fluid concentrations against drug-resistant Streptococcus pneumoniae 1
- Approximately 87% of S. pneumoniae isolates are susceptible to high-dose amoxicillin versus only 83% for standard-dose therapy 1
- Standard-dose amoxicillin (40-45 mg/kg/day) is inadequate to effectively eradicate resistant Streptococcus pneumoniae, particularly during viral coinfection 2
Volume Calculation for Liquid Formulation
If using liquid suspension (common concentrations):
- 400 mg/5 mL suspension: Give 13.75 mL twice daily (for 1100 mg dose) 1
- 250 mg/5 mL suspension: Give 22 mL twice daily (for 1100 mg dose) 1
Treatment Duration and Follow-Up
- Duration: 10 days of treatment 1
- Reassessment: Evaluate at 48-72 hours if symptoms do not improve or worsen 1
- Pain management: Address pain regardless of antibiotic choice 1
Alternative Therapy for Treatment Failure
- If the patient fails to improve within 48-72 hours on high-dose amoxicillin, switch to high-dose amoxicillin-clavulanate (90 mg/kg/day of amoxicillin component with 6.4 mg/kg/day clavulanate) 1
- For persistent failure, consider intramuscular ceftriaxone 50 mg/kg/day for 3-5 days 1
Common Pitfalls to Avoid
- Do not underdose: Physicians frequently prescribe significantly lower-than-recommended amoxicillin doses in older children and those in higher weight categories 3
- Do not use standard adult dosing: This patient requires weight-based dosing, not the standard adult dose of 1500 mg/day 3
- Do not use standard-dose amoxicillin: The 40-45 mg/kg/day dosing is inadequate for current resistance patterns 2, 4