What is the appropriate dosage of amoxicillin (400/5ml suspension) for an 80-pound child with an ear infection?

Amoxicillin Dosing for an 80-Pound Child with Ear Infection

For an 80-pound (36 kg) child with an ear infection, administer 8.2 mL of the 400 mg/5 mL amoxicillin suspension twice daily (every 12 hours) for 10 days. 1, 2

Dosage Calculation

• Weight conversion: 80 pounds = 36.3 kg
• Standard dosing for ear infections: 45 mg/kg/day divided into 2 doses 1, 2
• Total daily dose: 45 mg/kg/day × 36.3 kg = 1,634 mg/day
• Per-dose amount: 1,634 mg ÷ 2 = 817 mg per dose
• Volume per dose: 817 mg ÷ (400 mg/5 mL) = 8.2 mL twice daily 2

Treatment Duration and Monitoring

• Complete a full 10-day course of treatment, even if symptoms improve earlier 1, 2
• The child should demonstrate clinical improvement within 48-72 hours of starting therapy 1, 2
• If no improvement occurs within this timeframe, reevaluation is necessary and alternative antibiotics should be considered 1

Administration Instructions

• Give at the start of meals to minimize gastrointestinal side effects 2
• Shake the suspension well before each dose 2
• The medication can be mixed with formula, milk, fruit juice, water, or cold drinks if needed, but must be taken immediately after mixing 2
• Store the reconstituted suspension in the refrigerator (preferred but not required) and discard after 14 days 2

Important Clinical Considerations

High-dose amoxicillin (80-90 mg/kg/day) is NOT routinely necessary for most children with uncomplicated ear infections unless specific risk factors are present. 1, 3, 4 The standard dose of 45 mg/kg/day is appropriate for this patient and provides adequate coverage for most bacterial pathogens causing acute otitis media. 1, 2

When to Consider High-Dose Therapy (90 mg/kg/day):

• Child attends daycare 4
• Recent antibiotic use within the past 4 weeks 4
• Geographic areas with high pneumococcal resistance 1
• Severe infection or treatment failure 1, 2

For this 80-pound child, high-dose therapy would require 9.1 mL twice daily (90 mg/kg/day = 1,817 mg per dose). 1

Common Pitfalls to Avoid

• Do not underdose: The 400 mg/5 mL concentration requires careful calculation; using adult dosing or rounding down significantly can lead to treatment failure 1
• Do not stop early: Even if symptoms resolve quickly, completing the full 10-day course prevents recurrence and reduces antibiotic resistance 1, 2
• Do not use expired suspension: Discard any unused medication after 14 days from reconstitution 2