Amoxicillin Dosing for a 100-Pound Pediatric Patient
For a 100-pound (45.4 kg) pediatric patient, the recommended amoxicillin dosage is 1000 mg twice daily (approximately 45 mg/kg/day divided every 12 hours) for most uncomplicated infections, with treatment duration of 10 days for streptococcal infections. 1, 2
Weight-Based Dosing Algorithm
Since this patient weighs >40 kg, they should follow adult dosing recommendations rather than pediatric weight-based calculations 3:
For mild to moderate ear/nose/throat, skin, or genitourinary infections: 500 mg every 12 hours or 250 mg every 8 hours 3
For severe infections or lower respiratory tract infections: 875 mg every 12 hours or 500 mg every 8 hours 3
For Group A Streptococcal pharyngitis: 50-75 mg/kg/day divided into 2 doses for 10 days, which translates to approximately 1100-1650 mg twice daily, though not exceeding 1000 mg per dose 1, 2
Indication-Specific Considerations
The appropriate dose depends critically on the infection type and severity:
Community-acquired pneumonia (mild to moderate): Standard dosing of 500 mg every 12 hours is typically adequate 3
Community-acquired pneumonia (severe) or high-resistance areas: 875 mg every 12 hours provides better coverage against penicillin-resistant Streptococcus pneumoniae 2, 3
Acute otitis media with recent antibiotic exposure: High-dose amoxicillin-clavulanate (90 mg/kg/day of amoxicillin component, maximum 4000 mg/day) may be warranted for β-lactamase-producing organisms 1, 2
Critical Dosing Parameters
The maximum daily dose should not exceed 4000 mg regardless of weight or indication 2. For this 45.4 kg patient, standard adult dosing applies since they exceed the 40 kg threshold 3.
Treatment Duration
Streptococcal infections require a minimum 10-day course to prevent acute rheumatic fever 3
Most respiratory infections: 7-10 days, with pneumonia specifically requiring 10 days 1, 2
Treatment should continue for 48-72 hours beyond symptom resolution 3
Administration Guidelines
Amoxicillin should be taken at the start of a meal to minimize gastrointestinal intolerance 3
Clinical improvement should be evident within 48-72 hours; if no improvement occurs, reevaluation is necessary 1, 2
Common Pitfalls to Avoid
Do not substitute two 250 mg tablets for one 500 mg tablet when using amoxicillin-clavulanate formulations, as this results in excessive clavulanate dosing 1
For patients with recent antibiotic exposure (within 30 days), daycare attendance, or age <2 years, consider high-dose therapy even for uncomplicated infections 1, 2
Ensure the prescription specifies the daily dose, number of divided doses, duration of therapy, indication, and patient weight to prevent dispensing errors 4