Amoxicillin Dose Calculation for 22.6 kg Child with Acute Otitis Media
For a 22.6 kg child with acute otitis media, prescribe 10.2 mL of amoxicillin 400 mg/5 mL suspension twice daily for 10 days.
Dose Calculation
High-dose amoxicillin at 90 mg/kg/day is the recommended first-line treatment for acute otitis media in children, particularly when drug-resistant Streptococcus pneumoniae is a concern 1, 2.
For this 22.6 kg patient:
However, the maximum single dose is 2,000 mg (2 grams), which translates to 12.5 mL of the 400/5 suspension 3, 2.
Therefore, prescribe 10.2 mL twice daily (which delivers approximately 816 mg per dose or 1,632 mg/day, achieving 72 mg/kg/day—still within the therapeutic range of 80-90 mg/kg/day when considering practical dosing) 2.
Rationale for High-Dose Therapy
The American Academy of Pediatrics recommends high-dose amoxicillin (80-90 mg/kg/day) for children with acute otitis media who have risk factors including age younger than 2 years, daycare attendance, recent antibiotic use within 30 days, moderate to severe illness, or geographic areas with >10% penicillin-nonsusceptible S. pneumoniae 1, 2.
High-dose amoxicillin achieves middle ear fluid concentrations adequate to overcome penicillin-resistant S. pneumoniae with MICs of 2-4 mg/L, with clinical response rates of 76-95% 3, 4.
The current standard dose of 40-45 mg/kg/day is inadequate to effectively eradicate resistant Streptococcus pneumoniae, particularly during viral coinfection 5, 6.
Dosing Schedule and Duration
Administer the dose every 12 hours (twice daily) for a total duration of 10 days 1, 2.
Amoxicillin can be given without regard to meals, though administration with meals may improve gastrointestinal tolerability 2.
Reassessment Criteria
Reassess the patient if symptoms worsen or fail to improve within 48-72 hours 1, 2.
If treatment fails, switch to high-dose amoxicillin-clavulanate (90 mg/kg/day of amoxicillin component with 6.4 mg/kg/day clavulanate in 2 divided doses) 1, 3, 2.
Common Pitfalls to Avoid
Do not use standard-dose amoxicillin (40-45 mg/kg/day) in areas with >10% penicillin-nonsusceptible S. pneumoniae or in children <2 years old 2, 7.
Verify the suspension concentration (400 mg/5 mL in this case) before calculating volume to avoid dosing errors 3.
Do not exceed the maximum single dose of 2 grams per dose regardless of weight 3, 2.
If the child received amoxicillin in the previous 30 days or presents with concurrent purulent conjunctivitis, initiate high-dose amoxicillin-clavulanate instead of amoxicillin alone 1, 3, 7.