Amoxicillin Dosing for 3-Year-Old with Strep Pharyngitis
For this 13 kg child with streptococcal pharyngitis, administer 650 mg of amoxicillin once daily (which equals 16.25 mL of the 200mg/5mL suspension) for 10 days. 1, 2
Dosing Calculation
- The recommended dose is 50 mg/kg once daily (maximum 1,000 mg) for 10 days 1, 2
- For this 13 kg child: 50 mg/kg × 13 kg = 650 mg once daily 1, 2
- Using the 200mg/5mL suspension: (650 mg ÷ 200 mg) × 5 mL = 16.25 mL once daily 3
Alternative Dosing Regimen
- If once-daily dosing is not preferred, the alternative is 25 mg/kg twice daily (maximum 500 mg per dose) 1, 2
- For this child: 25 mg/kg × 13 kg = 325 mg twice daily = 8.125 mL twice daily 1, 3
Critical Treatment Principles
- Complete the full 10-day course regardless of symptom improvement to prevent acute rheumatic fever 1, 2, 4, 3
- The child becomes non-contagious after 24 hours of antibiotic therapy, but treatment must continue for the full duration 2, 4
- Administer at the start of a meal to minimize gastrointestinal intolerance 3
Evidence Quality and Strength
- This dosing recommendation carries a "Strong, high" evidence rating from the Infectious Diseases Society of America 1, 2, 4
- Once-daily amoxicillin has been shown to be non-inferior to multiple daily dosing in large controlled trials, with bacteriologic failure rates of 5% for once-daily versus 11% for three-times-daily dosing 5, 6
- Real-time PCR studies demonstrate equivalent bacterial eradication between once-daily and multiple-daily regimens 7
Important Considerations
- Shake the oral suspension well before each use 3
- After reconstitution, the suspension must be discarded after 14 days; refrigeration is preferable but not required 3
- The suspension can be mixed with formula, milk, fruit juice, or water if the child refuses direct administration, but must be taken immediately after mixing 3
Penicillin Allergy Alternatives (If Applicable)
- For documented penicillin allergy: cephalexin 20 mg/kg/dose twice daily (260 mg = 6.5 mL twice daily for this child) for 10 days 1, 4
- Avoid cephalosporins in immediate-type hypersensitivity reactions 1
- Other alternatives include clindamycin 7 mg/kg three times daily or azithromycin 12 mg/kg once daily for 5 days, though macrolide resistance varies geographically 1, 4