Amoxicillin Dosing for a 10-Year-Old Weighing 33.75 kg
For a 10-year-old male weighing 33.75 kg, the appropriate dose of amoxicillin (400 mg/5 mL) is 40 mg/kg/day divided into three doses, which equals approximately 450 mg (5.6 mL) three times daily. 1
Dosing Calculation
The FDA-approved dosing for amoxicillin in children is based on weight and severity of infection:
For mild to moderate infections:
- 20-25 mg/kg/day divided every 8 hours (three times daily)
- OR 25 mg/kg/day divided every 12 hours (twice daily)
For severe infections:
- 40-45 mg/kg/day divided every 8 hours (three times daily)
- OR 45 mg/kg/day divided every 12 hours (twice daily) 1
For this 10-year-old child weighing 33.75 kg:
- Mild/moderate infection dose: 33.75 kg × 25 mg/kg/day = 844 mg/day
- Divided three times daily = approximately 281 mg (3.5 mL) per dose
- Severe infection dose: 33.75 kg × 40 mg/kg/day = 1350 mg/day
- Divided three times daily = approximately 450 mg (5.6 mL) per dose
Administration Guidelines
- Administer at the start of a meal to minimize gastrointestinal intolerance 1
- Shake the oral suspension well before using
- The reconstituted suspension should be refrigerated (preferred) and discarded after 14 days
- Treatment should continue for a minimum of 48-72 hours after the patient becomes asymptomatic 1
- For Streptococcal infections, a minimum of 10 days of treatment is recommended to prevent acute rheumatic fever 1
Important Clinical Considerations
- The British Thoracic Society guidelines also support this dosing approach for respiratory infections 2
- Higher doses (40-45 mg/kg/day) are recommended for more severe infections or those caused by less susceptible organisms 1
- For children with renal impairment, dose adjustments may be necessary if GFR is less than 30 mL/min 1
- Amoxicillin absorption appears to be saturable, so dividing the total daily dose into three administrations rather than two may provide more consistent coverage 3
Practical Administration Tips
- For the 400 mg/5 mL concentration:
- Mild/moderate infection: 3.5 mL three times daily
- Severe infection: 5.6 mL three times daily
- Use a calibrated measuring device for accurate dosing
- Complete the full course of antibiotics even if symptoms improve before completion