Amoxicillin Dosing for Tonsillitis in a 6-Year-Old, 28.4kg Patient
For this 6-year-old patient weighing 28.4kg with tonsillitis, prescribe amoxicillin 1,278 mg per day divided into two doses (639 mg twice daily) or three doses (426 mg three times daily), which can be practically administered as 650 mg twice daily or 425 mg three times daily for 10 days. 1
Dosing Calculation and Rationale
The FDA-approved dosing for pediatric patients aged 3 months and older with ear/nose/throat infections recommends 45 mg/kg/day in divided doses every 12 hours for severe infections or 40 mg/kg/day in divided doses every 8 hours 1
For this 28.4kg patient, the calculation yields:
- 45 mg/kg/day = 1,278 mg/day (divided as 639 mg twice daily)
- 40 mg/kg/day = 1,136 mg/day (divided as approximately 379 mg three times daily)
Given that tonsillitis caused by Group A Streptococcus requires adequate dosing to prevent acute rheumatic fever, the higher dosing regimen (45 mg/kg/day) is preferred 1
Practical Administration
Administer at the start of meals to minimize gastrointestinal intolerance 1
Twice-daily dosing is as efficacious as more frequent dosing regimens and significantly improves compliance 2
The oral suspension can be mixed with formula, milk, fruit juice, water, or cold drinks and should be taken immediately after mixing 1
Treatment Duration
Continue treatment for a minimum of 10 days for any infection caused by Streptococcus pyogenes to prevent acute rheumatic fever 1
Treatment should continue for at least 48-72 hours beyond when the patient becomes asymptomatic 1
Research supports that 10-day courses are more effective than shorter 5-6 day regimens for streptococcal tonsillopharyngitis in children, particularly for bacteriologic eradication 3, 4
Monitoring and Follow-Up
Assess for clinical improvement within 48-72 hours of starting treatment 5
Common side effects include gastrointestinal disturbances (diarrhea, nausea, vomiting) and rash 5
If no improvement occurs within 48-72 hours or clinical deterioration develops, reevaluation is necessary 5
Important Clinical Considerations
Amoxicillin demonstrates superior tissue penetration compared to other antibiotics, though concentrations in tonsillar tissue may be lower than serum levels 6
The twice-daily dosing regimen (every 12 hours) is strongly supported by meta-analysis data showing equivalent efficacy to more frequent dosing schedules while improving adherence 2
Shake oral suspension well before each use and refrigerate after reconstitution (though not required); discard any unused portion after 14 days 1