Amoxicillin Suspension Dosing for Otitis Media in a 5-Year-Old Child
For a 5-year-old child weighing 40 pounds (18.2 kg) with otitis media, prescribe amoxicillin suspension 80-90 mg/kg/day divided into two doses, which equals approximately 730-820 mg twice daily (or 1,460-1,640 mg total daily dose). 1, 2
Weight-Based Dose Calculation
- 40 pounds = 18.2 kg 1, 2
- Recommended dosing: 80-90 mg/kg/day 3, 1, 2
- Total daily dose: 1,456-1,638 mg/day 1, 2
- Practical twice-daily dosing: 730-820 mg per dose (every 12 hours) 1, 2
- Alternative three-times-daily dosing: 485-545 mg per dose (every 8 hours) 1
Rationale for High-Dose Amoxicillin
High-dose amoxicillin (80-90 mg/kg/day) is the first-line antibiotic for acute otitis media when treatment is indicated, as recommended by the American Academy of Pediatrics. 3, 1, 2
- This higher dosing (compared to the older standard of 40-45 mg/kg/day) is necessary due to increasing prevalence of penicillin-resistant Streptococcus pneumoniae 1, 2, 4
- High-dose amoxicillin achieves middle ear fluid concentrations adequate to eradicate resistant organisms, particularly when viral coinfection is present 5
- Research demonstrates that standard-dose amoxicillin (40 mg/kg/day) is inadequate for resistant S. pneumoniae, especially during viral coinfection 5
- Bacteriologic studies show 92% eradication of S. pneumoniae (including penicillin-nonsusceptible strains) with high-dose amoxicillin 4
Practical Prescribing Details
Available suspension concentrations:
- 125 mg/5 mL or 250 mg/5 mL 6
For 750 mg twice daily (using 250 mg/5 mL suspension):
- Give 15 mL (3 teaspoons) twice daily 6
For 800 mg twice daily (using 250 mg/5 mL suspension):
- Give 16 mL twice daily 2
Administration instructions:
- Give at the start of a meal to minimize gastrointestinal intolerance 6
- Shake suspension well before each use 6
- Suspension can be mixed with formula, milk, fruit juice, water, or cold drinks if needed, and should be taken immediately 6
Treatment Duration
Treat for 10 days in children under 6 years of age with acute otitis media. 7, 6
- The American Academy of Pediatrics recommends a minimum 10-day course for children under 6 years 7
- Continue treatment for at least 48-72 hours beyond symptom resolution 6
When to Use Amoxicillin-Clavulanate Instead
Switch to amoxicillin-clavulanate (Augmentin) if: 3, 7, 2
- The child received amoxicillin in the past 30 days 3, 7, 2
- Concurrent purulent conjunctivitis is present 3, 7
- History of recurrent AOM unresponsive to amoxicillin 3
- The child attends daycare with high exposure to resistant organisms 7
The primary reason for treatment failure with high-dose amoxicillin is beta-lactamase-producing Haemophilus influenzae (62% eradication rate vs. 84% for non-beta-lactamase producers), which requires beta-lactamase coverage 4
Monitoring and Reassessment
Reassess the patient at 48-72 hours if symptoms worsen or fail to improve. 3, 7, 2
- Treatment failure is defined as worsening condition, persistence of symptoms beyond 48 hours, or recurrence within 4 days of completing therapy 2
- If treatment failure occurs, switch to amoxicillin-clavulanate or another antibiotic with beta-lactamase coverage 3, 2
- Provide appropriate pain management during the first 24 hours regardless of antibiotic use 2
Common Pitfalls to Avoid
- Underdosing: Using the older standard dose (40-45 mg/kg/day) instead of high-dose (80-90 mg/kg/day) leads to treatment failure, particularly with resistant S. pneumoniae 1, 2, 5
- Incorrect weight conversion: Always verify the child's weight in kilograms (40 lbs = 18.2 kg, not 20 kg) 1
- Inadequate duration: Treating for less than 10 days in young children increases risk of recurrence 7, 6
- Not recognizing treatment failure: Failure to reassess at 48-72 hours and switch to broader-spectrum coverage when indicated 3, 2
- Improper storage: Reconstituted suspension must be discarded after 14 days; refrigeration is preferable but not required 6