What is the appropriate dosing of Amoxicillin (Amox) 400mg/5ml for a 63-pound pediatric patient?

Amoxicillin 400mg/5ml Dosing for a 63-Pound Child

For a 63-pound (28.6 kg) child, administer 6.4 mL of amoxicillin 400mg/5ml suspension twice daily for standard respiratory infections, or 12.9 mL twice daily for severe infections or high-resistance areas.

Weight-Based Calculation

• A 63-pound child weighs 28.6 kg 1
• The standard dose for uncomplicated respiratory tract infections is 45 mg/kg/day divided every 12 hours 1
• This calculates to 1,287 mg/day total, or 643.5 mg per dose (approximately 8 mL twice daily of 400mg/5ml suspension) 1

Indication-Specific Dosing Algorithm

For Mild to Moderate Respiratory Infections

• Administer 45 mg/kg/day divided into 2 doses, which equals approximately 6.4 mL of 400mg/5ml suspension twice daily 1
• This provides adequate coverage for most susceptible pathogens including Streptococcus pneumoniae, Haemophilus influenzae (non-β-lactamase producing), and Streptococcus pyogenes 1

For Severe Infections or High-Resistance Areas

• Administer 90 mg/kg/day divided into 2 doses, which equals approximately 12.9 mL of 400mg/5ml suspension twice daily 1
• This high-dose regimen is indicated for community-acquired pneumonia in areas with >10% penicillin-resistant S. pneumoniae, children <2 years old, recent antibiotic exposure within the past 30 days, children attending daycare, or severe infections requiring hospitalization 1

For Group A Streptococcal Pharyngitis

• Administer 50-75 mg/kg/day divided into 2 doses for 10 days, which equals approximately 14-21 mL of 400mg/5ml suspension twice daily, not exceeding 1000 mg per dose 1

Critical Dosing Considerations

• The maximum daily dose of amoxicillin should not exceed 4000 mg/day regardless of weight 1
• For β-lactamase-producing organisms (H. influenzae, M. catarrhalis), switch to amoxicillin-clavulanate (Augmentin) at 90 mg/kg/day of the amoxicillin component 1
• Treatment duration should typically be 7-10 days for most respiratory infections, with pneumonia specifically requiring 10 days 1

Monitoring and Follow-Up

• Children on appropriate antibiotic therapy should show clinical improvement within 48-72 hours 1
• If no improvement is seen within this timeframe, reevaluation is necessary and consider switching antibiotics or investigating for complications 1
• Complete the full course of antibiotics as prescribed, even if symptoms improve before completion 1

Common Pitfalls to Avoid

• Do not underdose older or heavier children by capping at standard adult doses prematurely—primary care physicians frequently prescribe significantly lower-than-recommended doses in higher weight categories 2
• Verify the suspension concentration (200mg/5ml vs 400mg/5ml) before calculating volume to avoid dosing errors 1
• The twice-daily dosing regimen improves compliance compared to three-times-daily dosing while maintaining therapeutic efficacy 3