What is the recommended dosage of Amoxicillin (Amox) 400mg/5ml for a 9-year-old patient weighing 61 pounds?

Amoxicillin 400mg/5ml Dosing for a 9-Year-Old Weighing 61 Pounds

For a 9-year-old child weighing 61 pounds (27.7 kg), the recommended dose of amoxicillin 400mg/5ml is 8.7 mL twice daily (every 12 hours) for standard respiratory tract infections, or 17.4 mL twice daily for severe infections or areas with high pneumococcal resistance. 1

Weight-Based Calculation

• The child weighs 61 pounds, which converts to 27.7 kg 1
• For mild to moderate respiratory tract infections, the standard dose is 45 mg/kg/day divided into 2 doses, which equals 1,247 mg per day or approximately 623 mg per dose 1, 2
• Using the 400mg/5ml suspension, this translates to 8.7 mL twice daily (every 12 hours) 1
• For severe infections or high pneumococcal resistance areas, the dose is 90 mg/kg/day divided into 2 doses, which equals 2,493 mg per day or approximately 1,247 mg per dose 1
• This higher dose translates to 17.4 mL twice daily using the 400mg/5ml suspension 1

Indication-Specific Dosing Algorithm

For Standard Respiratory Infections (Mild to Moderate)

• Dose: 45 mg/kg/day in 2 divided doses 1, 2
• For this 27.7 kg child: 8.7 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-Risk Situations

• Dose: 90 mg/kg/day in 2 divided doses 1, 2
• For this 27.7 kg child: 17.4 mL of 400mg/5ml suspension twice daily 1
• High-dose therapy is indicated for: 1
  • 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
  • Severe infections requiring hospitalization

For Group A Streptococcal Infections (Strep Throat, Scarlet Fever)

• Dose: 50-75 mg/kg/day in 2 divided doses for 10 days 1
• For this 27.7 kg child: 11-14.5 mL of 400mg/5ml suspension twice daily 1
• Maximum dose per intake should not exceed 1000 mg 1

Treatment Duration

• Respiratory infections: 7-10 days 1
• Pneumonia specifically: 10 days 1
• Streptococcal infections: 10 days (critical to prevent acute rheumatic fever) 2
• Treatment should continue for a minimum of 48-72 hours beyond the time the patient becomes asymptomatic 2

Administration Instructions

• Amoxicillin should be taken at the start of a meal to minimize gastrointestinal intolerance 2
• Shake the suspension well before each use 2
• The suspension can be mixed with formula, milk, fruit juice, water, ginger ale, or cold drinks, and should be taken immediately after mixing 2
• Store the reconstituted suspension in the refrigerator (preferred but not required) and discard any unused portion after 14 days 2

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 1
• Complete the full course of antibiotics as prescribed, even if symptoms improve before completion 1

Critical Considerations and Common Pitfalls

• Never underdose: The standard 45 mg/kg/day dose is appropriate only for uncomplicated infections without risk factors 1
• Consider high-dose therapy (90 mg/kg/day) if: 1
  • The child has received antibiotics in the past 30 days
  • The child attends daycare
  • Local pneumococcal resistance rates are high
  • The infection is severe
• Maximum daily dose: Do not exceed 4000 mg/day regardless of weight 1
• For β-lactamase-producing organisms: Consider switching to amoxicillin-clavulanate (Augmentin) at 90 mg/kg/day of the amoxicillin component 1, 3
• Verify the suspension concentration before calculating the volume to avoid dosing errors 1