Amoxicillin Dosing for Streptococcal Pharyngitis in a 34‑kg Child
Give 12.5 mL of amoxicillin 400 mg/5 mL suspension once daily for 10 days.
Dose Calculation
The recommended pediatric dose is 50 mg/kg once daily (maximum 1000 mg/day) for Group A streptococcal pharyngitis. 1
For a 34‑kg child: 50 mg/kg × 34 kg = 1700 mg, but this exceeds the maximum allowable dose. 1
The dose must be capped at 1000 mg per day for once‑daily regimens to prevent overtreatment while maintaining efficacy. 1
Using the 400 mg/5 mL suspension: 1000 mg ÷ 400 mg = 2.5 × 5 mL = 12.5 mL once daily. 2
Rationale for Once‑Daily Dosing
Once‑daily amoxicillin 1000 mg for 10 days is the preferred regimen for children, providing effective eradication of Streptococcus pyogenes and improving adherence compared to multiple‑daily dosing schedules. 1
Strong, high‑quality evidence from the IDSA guideline supports once‑daily dosing as equivalent in efficacy to traditional twice‑ or thrice‑daily regimens. 1, 3
Molecular biology studies using real‑time PCR confirm that once‑daily amoxicillin is as effective in eradicating GAS as twice‑ or thrice‑daily regimens. 4
Alternative Twice‑Daily Regimen
If once‑daily dosing is not feasible, give 475 mg (approximately 6 mL of 400 mg/5 mL suspension) twice daily for 10 days, which delivers a total daily dose of approximately 950 mg. 1
This twice‑daily alternative provides approximately 25 mg/kg per dose and is supported by strong, high‑quality evidence. 1
Mandatory Treatment Duration
A full 10‑day course is mandatory to reliably prevent acute rheumatic fever, regardless of early symptom resolution. 1, 3, 2
The FDA label explicitly states that at least 10 days' treatment is required for any infection caused by Streptococcus pyogenes to prevent acute rheumatic fever. 2
Clinical improvement within 24–48 hours does not justify shortening therapy; the full 10‑day course must be completed. 1
Administration Instructions
Administer at the start of a meal to minimize gastrointestinal intolerance. 2
Shake the suspension well before each use and keep the bottle tightly closed. 2
Refrigeration is preferable but not required; discard any unused portion after 14 days. 2
Common Pitfalls to Avoid
Never exceed 1000 mg per day for once‑daily regimens or 500 mg per individual dose for twice‑daily regimens to avoid unnecessary toxicity. 1, 3
Do not shorten the 10‑day course even if symptoms resolve early; this is essential for rheumatic fever prevention. 1, 3
Do not use macrolides (azithromycin, clarithromycin) as first‑line therapy because regional resistance rates are 5–8% in most U.S. areas. 1, 3