What is the recommended dose of Amoxicillin (amoxicillin) for an 11-year-old patient weighing 59.87 kg with streptococcal pharyngitis?

Amoxicillin Dosing for Streptococcal Pharyngitis

For this 11-year-old patient weighing 59.87 kg with streptococcal pharyngitis, prescribe amoxicillin 1000 mg once daily for 10 days, or alternatively 500 mg twice daily for 10 days. 1

Weight-Based Dosing Calculation

• The IDSA guideline recommends 50 mg/kg once daily (maximum 1000 mg) for children with streptococcal pharyngitis 1
• For this patient: 50 mg/kg × 59.87 kg = 2993.5 mg, which exceeds the maximum dose of 1000 mg 1
• Therefore, use the maximum dose of 1000 mg once daily 1, 2

Alternative Dosing Regimen

• The twice-daily alternative is 25 mg/kg twice daily, which calculates to approximately 1497 mg/day for this patient 1
• This also exceeds the maximum, so use 500 mg twice daily (1000 mg total daily dose) 1, 2
• Both once-daily and twice-daily regimens have strong, high-quality evidence for efficacy 1

Practical Pill Formulations

• Once-daily option: One 1000-mg tablet (or two 500-mg tablets) taken once daily 2
• Twice-daily option: One 500-mg tablet taken every 12 hours 2
• The once-daily regimen may improve adherence, which is particularly important for the required 10-day course 3, 4

Critical Treatment Duration

• A full 10-day course is mandatory to prevent acute rheumatic fever, regardless of symptom resolution 1, 2
• Treatment should continue even if the patient becomes asymptomatic before completing the course 2

Administration Instructions

• Amoxicillin should be taken at the start of a meal to minimize gastrointestinal intolerance 2
• If using oral suspension instead of tablets, shake well before each dose and refrigerate (though not required) 2

Common Pitfalls to Avoid

• Do not underdose: This patient's weight places them at the maximum adult dose; using pediatric weight-based calculations without applying the maximum cap would be incorrect 1, 2
• Do not shorten the course: Even though symptoms typically resolve in 3-4 days, the full 10-day course is essential for preventing rheumatic fever 1, 2
• Do not use azithromycin as first-line: Penicillin or amoxicillin remains the drug of choice due to narrow spectrum, low cost, and lack of resistance 1