Amoxicillin Dosing for Strep Throat in a 28.1kg 6-Year-Old Female
For this 28.1kg 6-year-old with streptococcal pharyngitis, prescribe amoxicillin 750 mg once daily (or alternatively 375 mg twice daily) for a full 10 days. 1, 2, 3
Weight-Based Dosing Calculation
The recommended dose is 50 mg/kg once daily (maximum 1,000 mg) or 25 mg/kg twice daily (maximum 500 mg per dose) for 10 days. 1, 2
For this 28.1kg child: 28.1 kg × 50 mg/kg = 1,405 mg, which exceeds the maximum daily dose of 1,000 mg, so the dose should be capped at 750 mg once daily (since she weighs <40 kg). 1, 2, 3
Alternative twice-daily dosing: 28.1 kg × 25 mg/kg = 702.5 mg per dose, which can be rounded to 375 mg twice daily. 1, 2
Critical Treatment Duration
A full 10-day course is absolutely essential to prevent acute rheumatic fever, regardless of symptom resolution. 4, 1, 3
The FDA label explicitly states: "It is recommended that there be at least 10 days' treatment for any infection caused by Streptococcus pyogenes to prevent the occurrence of acute rheumatic fever." 3
Symptoms typically resolve within 3-4 days, but stopping antibiotics early dramatically increases treatment failure rates and rheumatic fever risk. 5, 1
Why Once-Daily Dosing is Preferred
Once-daily amoxicillin has strong, high-quality evidence demonstrating non-inferiority to multiple-daily dosing regimens. 1, 2, 6, 7
The American Heart Association recently endorsed once-daily amoxicillin dosing for streptococcal pharyngitis. 2, 8
Once-daily dosing may improve adherence compared to multiple daily doses, which is particularly important for completing the full 10-day course. 2, 8
Multiple high-quality studies demonstrate bacteriologic eradication rates of 79-88% with once-daily amoxicillin, comparable to or better than conventional penicillin V. 9, 10, 6, 7
Administration Instructions
Amoxicillin should be taken at the start of a meal to minimize gastrointestinal intolerance. 3
For oral suspension, shake well before each use and discard any unused portion after 14 days. 3
The child will be considered non-contagious after 24 hours of antibiotic therapy. 2
Common Pitfalls to Avoid
Do not use the adult 875 mg tablet in children <40 kg, as this exceeds recommended pediatric dosing. 1
Do not prescribe shorter courses (e.g., 5-7 days) despite some studies suggesting efficacy, as current guidelines do not endorse this for routine therapy and it increases rheumatic fever risk. 5, 1
Do not stop antibiotics early even if the child feels better after 3-4 days, as bacterial eradication requires the full 10-day course. 5, 1, 3
Do not use sulfonamides (like Bactrim) or tetracyclines, which have high resistance rates and poor eradication of Group A Streptococcus. 5, 1
Alternative Regimens if Needed
If once-daily dosing is not feasible, twice-daily dosing of 375 mg (25 mg/kg/dose) is equally effective. 1, 2, 3
Three-times-daily dosing (250 mg TID) is also acceptable but may reduce adherence. 1, 3
If Penicillin Allergy Were Present
For non-immediate penicillin allergy: First-generation cephalosporins like cephalexin 20 mg/kg twice daily (maximum 500 mg/dose) for 10 days. 5, 2
For immediate/anaphylactic penicillin allergy: Clindamycin 7 mg/kg three times daily (maximum 300 mg/dose) for 10 days or azithromycin 12 mg/kg once daily (maximum 500 mg) for 5 days. 4, 5, 2