What is the recommended dose of amoxicillin (amoxicillin) for a child weighing 30 pounds (13.6 kilograms) with streptococcal pharyngitis?

Amoxicillin Dosing for Streptococcal Pharyngitis in a 30-pound Child

For a 30-pound (13.6 kg) child with streptococcal pharyngitis, the recommended dose of amoxicillin is 50 mg/kg/day, which equals 680 mg per day, divided into two doses (340 mg twice daily) or given as a single daily dose for 10 days. 1

Dosing Calculation and Options

• Weight-based calculation:

  • 30 pounds = 13.6 kg
  • At 50 mg/kg/day: 13.6 kg × 50 mg/kg = 680 mg daily

• Administration options:

  1. Twice-daily regimen: 340 mg every 12 hours for 10 days 1, 2
  2. Once-daily regimen: 680 mg once daily for 10 days 1, 3

Evidence for Dosing Recommendations

The most recent guidelines from Praxis Medical Insights recommend amoxicillin at 50 mg/kg once daily (maximum 1000 mg) or 25 mg/kg twice daily (maximum 500 mg per dose) for a full 10-day course 1. This is supported by the FDA drug label, which indicates that for streptococcal infections, amoxicillin should be administered for at least 10 days to prevent acute rheumatic fever 2.

Once-Daily vs. Twice-Daily Dosing

Recent research has demonstrated that once-daily amoxicillin dosing is not inferior to twice-daily dosing for streptococcal pharyngitis:

• A randomized non-inferiority trial showed comparable eradication rates between once-daily and twice-daily regimens 4
• A 2019 study using real-time PCR to measure bacterial load found no statistical difference in GAS eradication between once-daily, twice-daily, or three-times-daily dosing 3
• The American Heart Association has endorsed once-daily amoxicillin dosing for GAS pharyngitis 5

Duration of Treatment

A full 10-day course of treatment is essential for streptococcal pharyngitis, regardless of symptom resolution, to prevent complications such as acute rheumatic fever 1, 2. Treatment should not be shortened even if symptoms improve quickly.

Clinical Pearls and Pitfalls

• Common pitfall: Underdosing amoxicillin. Research suggests that higher doses (40-50 mg/kg/day) are more effective than traditional lower doses of penicillin V 6
• Important consideration: Medication should be taken at the start of a meal to minimize gastrointestinal intolerance 2
• Practical advantage: Once-daily dosing may improve medication adherence compared to multiple daily doses 5, 3
• Monitoring: The child should be considered non-contagious after 24 hours of appropriate antibiotic therapy 1

Alternative Options for Penicillin-Allergic Patients

For patients with penicillin allergy, alternative options include:

• Cephalexin: 20 mg/kg twice daily (maximum 500 mg per dose)
• Clindamycin: 7 mg/kg three times daily (maximum 300 mg per dose)
• Azithromycin: 12 mg/kg once daily (maximum 500 mg)

These alternatives should be used for the full recommended duration (10 days for cephalexin and clindamycin; 5 days for azithromycin) 1.