What is the recommended dose of amoxicillin (amox) in milliliters (mL) for a 5-year-old child weighing 21 kilograms (kg) with otitis media?

Amoxicillin Dosing for a 5-Year-Old with Otitis Media

For a 21 kg child with acute otitis media, prescribe amoxicillin 80-90 mg/kg/day divided into 2 doses, which equals 840-945 mg twice daily (1,680-1,890 mg total daily dose). 1, 2

Dose Calculation

• The recommended high-dose amoxicillin is 80-90 mg/kg/day for acute otitis media 1, 2
• For a 21 kg child:
  • 80 mg/kg/day = 1,680 mg/day
  • 90 mg/kg/day = 1,890 mg/day 1, 2
• Divide into twice-daily dosing: 840-945 mg per dose 1, 2
• Practical dosing: 850-900 mg twice daily (approximately 81-86 mg/kg/day) 1

Converting to Milliliters

• Amoxicillin suspension commonly comes in concentrations of 200 mg/5 mL, 250 mg/5 mL, or 400 mg/5 mL
• For 850 mg per dose using 400 mg/5 mL concentration: 10.6 mL twice daily
• For 850 mg per dose using 250 mg/5 mL concentration: 17 mL twice daily
• For 900 mg per dose using 400 mg/5 mL concentration: 11.25 mL twice daily 1, 2

Rationale for High-Dose Therapy

• High-dose amoxicillin (80-90 mg/kg/day) is first-line treatment because it provides effective coverage against drug-resistant Streptococcus pneumoniae while maintaining safety, low cost, acceptable taste, and narrow microbiologic spectrum 1, 3
• The American Academy of Pediatrics and American Academy of Family Physicians recommend this higher dosage over standard-dose (40-45 mg/kg/day) due to increasing prevalence of penicillin-resistant organisms 2, 3
• High-dose amoxicillin achieves bacteriologic eradication in 92% of S. pneumoniae cases, including penicillin-nonsusceptible strains 3

Treatment Duration

• For a 5-year-old child with uncomplicated acute otitis media, prescribe a 5-7 day course 1, 2
• Children over 2 years with uncomplicated disease require only 5 days of treatment 1
• Duration of 5-10 days is acceptable depending on severity and clinical response 1, 2

When to Switch Antibiotics

• Switch to amoxicillin-clavulanate (90 mg/kg/day of amoxicillin component) if:
  • The child received amoxicillin in the previous 30 days 1, 2
  • Concurrent purulent conjunctivitis is present 1, 2
  • Symptoms fail to improve or worsen at 48-72 hours 1, 2
• Beta-lactamase-producing H. influenzae is the predominant pathogen in treatment failures (62% bacteriologic failure rate with amoxicillin alone) 3

Critical Monitoring Points

• Reassess at 48-72 hours if symptoms fail to improve 1, 2
• Treatment failure is defined as worsening condition, persistence of symptoms beyond 48 hours, or recurrence within 4 days of completing therapy 1
• Provide pain management concurrently during the first 24 hours regardless of antibiotic use 1, 2

Common Pitfalls to Avoid

• Underdosing by using standard-dose (40-45 mg/kg/day) instead of high-dose amoxicillin leads to treatment failures 2, 4
• Failure to adjust dosing based on actual weight can result in subtherapeutic levels 2
• Not recognizing when to switch to broader-spectrum coverage (amoxicillin-clavulanate) in treatment failures 1, 2
• Prescribing three-times-daily dosing when twice-daily is equally effective and improves adherence 5