What amoxicillin dose and volume should be given to a 19.05‑kg child with streptococcal infection using a 400 mg/mL suspension?

Amoxicillin Dosing for Streptococcal Infection in a 19.05 kg Child

For this 19.05 kg child with streptococcal infection, prescribe 952.5 mg of amoxicillin once daily (2.4 mL of 400 mg/mL suspension) for 10 days. 1

Dosing Calculation

Weight-based calculation:

• The IDSA guideline recommends 50 mg/kg once daily (maximum 1,000 mg) for streptococcal pharyngitis 1
• For 19.05 kg: 50 mg/kg × 19.05 kg = 952.5 mg once daily 1
• This dose is well below the 1,000 mg maximum 1

Volume calculation with 400 mg/mL suspension:

• 952.5 mg ÷ 400 mg/mL = 2.4 mL once daily 2

Alternative twice-daily regimen:

• The IDSA also recommends 25 mg/kg twice daily (maximum 500 mg per dose) as an alternative 1
• For 19.05 kg: 25 mg/kg × 19.05 kg = 476.25 mg twice daily 1
• Volume: 476.25 mg ÷ 400 mg/mL = 1.2 mL twice daily 2

Treatment Duration and Administration

Duration:

• 10 days of treatment is mandatory for Group A streptococcal infections to prevent acute rheumatic fever 1, 3, 2
• Complete the full course even if symptoms improve 3

Administration instructions:

• Give at the start of a meal to minimize gastrointestinal intolerance 2
• Shake suspension well before each use 2
• Can be mixed with formula, milk, fruit juice, water, or cold drinks if needed, but must be taken immediately after mixing 2

Important Clinical Considerations

Strength of recommendation:

• This dosing regimen has strong recommendation with high-quality evidence from the IDSA 1

Common pitfall to avoid:

• Do not use the lower 40-90 mg/kg/day dosing range intended for multidrug-resistant organisms 1 for standard streptococcal pharyngitis, as the IDSA specifically recommends 50 mg/kg once daily for this indication 1