What is the recommended dose of amoxicillin (400mg/5ml) for a 5-year-old child with otitis media?

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

For a 5-year-old child with acute otitis media, prescribe high-dose amoxicillin at 80-90 mg/kg/day divided into two daily doses, which translates to approximately 8-10 mL of the 400mg/5mL suspension twice daily for an average-weight child. 1, 2

Dose Calculation Steps

To calculate the exact dose:

• Determine the child's weight in kilograms (average 5-year-old weighs approximately 18-20 kg) 2
• Multiply weight by 80-90 mg/kg/day to get total daily dose 1
• Divide by 2 for twice-daily dosing 2
• Convert to mL using the 400mg/5mL concentration (80 mg per mL)

For example, for a 20 kg child:

• Total daily dose: 1600-1800 mg/day (20 kg × 80-90 mg/kg) 2
• Per dose: 800-900 mg twice daily 2
• Volume per dose: 10-11.25 mL of 400mg/5mL suspension twice daily

Rationale for High-Dose Therapy

High-dose amoxicillin (80-90 mg/kg/day) is the first-line treatment because it:

• Provides effective coverage against drug-resistant Streptococcus pneumoniae, achieving middle ear fluid levels that exceed the minimum inhibitory concentration for intermediately and many highly resistant strains 1, 3
• Maintains excellent safety profile, low cost, acceptable taste, and narrow microbiologic spectrum 1, 2
• Achieves 92% eradication of S. pneumoniae including penicillin-resistant strains 3

Treatment Duration

Prescribe for 5-10 days depending on severity and age: 2

• Children ≥2 years with uncomplicated AOM: 5 days is sufficient 2
• Younger children or severe cases: consider 10 days 1, 3

When to Switch Antibiotics

Use amoxicillin-clavulanate (90 mg/kg/day of amoxicillin component with 6.4 mg/kg/day clavulanate) instead if: 1, 2

• Child received amoxicillin in the previous 30 days 1
• Concurrent purulent conjunctivitis is present 1
• Coverage for beta-lactamase-producing H. influenzae or M. catarrhalis is needed 1, 2

Follow-Up and Treatment Failure

Reassess at 48-72 hours if symptoms fail to improve: 2

• Treatment failure is defined as worsening condition, persistence of symptoms beyond 48 hours, or no improvement by 48-72 hours 2
• Switch to amoxicillin-clavulanate or ceftriaxone if treatment failure occurs 2
• Beta-lactamase-producing H. influenzae is the most common cause of amoxicillin treatment failure 2, 3

Critical Pitfalls to Avoid

Common dosing errors include:

• Using standard-dose amoxicillin (40 mg/kg/day) instead of high-dose, which provides inadequate coverage for resistant S. pneumoniae 1, 4
• Failing to account for the child's actual weight, leading to underdosing 2
• Not addressing pain management concurrently during the first 24 hours 2