What is the appropriate amoxicillin dosage for a child weighing 67.4 lb (≈30.6 kg)?

Amoxicillin Dosing for a Child Weighing 67.4 lbs (30.6 kg)

For a child weighing 67.4 lbs (30.6 kg), the appropriate amoxicillin dosage depends on the indication: for mild to moderate infections, prescribe 45 mg/kg/day divided into two doses (approximately 690 mg twice daily), and for severe infections or high-resistance areas, prescribe 90 mg/kg/day divided into two doses (approximately 1380 mg twice daily). 1, 2

Weight-Based Dosing Algorithm

Standard Dosing (45 mg/kg/day):

• For uncomplicated respiratory tract infections, skin infections, and genitourinary infections, the American Academy of Pediatrics recommends 45 mg/kg/day divided every 12 hours 1, 2
• For this 30.6 kg child, this equals approximately 1377 mg/day, or 690 mg twice daily 1
• This dosing provides adequate coverage for most susceptible pathogens including Streptococcus pneumoniae, Haemophilus influenzae (non-β-lactamase producing), and Streptococcus pyogenes 1

High-Dose Regimen (90 mg/kg/day):

• For severe infections, community-acquired pneumonia in high-resistance areas, or recent antibiotic exposure within 30 days, the Infectious Diseases Society of America recommends 90 mg/kg/day divided every 12 hours 1, 2
• For this 30.6 kg child, this equals approximately 2754 mg/day, or 1380 mg twice daily 1
• The maximum daily dose should not exceed 4000 mg/day regardless of weight 1

Indication-Specific Dosing

Community-Acquired Pneumonia:

• Mild to moderate outpatient cases: 45 mg/kg/day (690 mg twice daily) 1
• Severe cases or high pneumococcal resistance (>10%): 90 mg/kg/day (1380 mg twice daily) 1, 2
• The Pediatric Infectious Diseases Society recommends 90 mg/kg/day in 2 doses for children ≥5 years old with pneumonia 2

Acute Otitis Media:

• Standard dosing: 40-45 mg/kg/day in 2 divided doses 2
• High-dose for recent antibiotic use (within 4-6 weeks): 80-90 mg/kg/day 3, 1
• The American Academy of Family Physicians recommends high-dose amoxicillin (80-90 mg/kg/day) as first-line therapy to address drug-resistant Streptococcus pneumoniae 3

Streptococcal Pharyngitis:

• The American Academy of Family Physicians recommends 50-75 mg/kg/day divided into 2 doses for 10 days 1
• For this child: approximately 1530-2295 mg/day, or 765-1150 mg twice daily, not exceeding 1000 mg per dose 1

Acute Bacterial Sinusitis:

• Children ≥2 years without risk factors: 45 mg/kg/day divided every 12 hours 1
• Children <2 years, in daycare, or with recent antibiotic use: 80-90 mg/kg/day divided every 12 hours 1

Practical Administration Considerations

Formulation Selection:

• The FDA label indicates that for children weighing less than 40 kg, weight-based dosing should be used 4
• Since this child weighs 30.6 kg (less than 40 kg), use pediatric weight-based dosing rather than adult fixed doses 4
• Oral suspension concentrations of 250 mg/5 mL or 400 mg/5 mL are commonly available 3
• For 690 mg dose: approximately 14 mL of 250 mg/5 mL suspension or 8.6 mL of 400 mg/5 mL suspension 3
• Amoxicillin should be taken at the start of a meal to minimize gastrointestinal intolerance 4

Treatment Duration and Monitoring

Duration:

• Most respiratory infections: 7-10 days 1, 2
• Pneumonia specifically: 10 days 2
• Streptococcal pharyngitis: 10 days to prevent acute rheumatic fever 4
• The WHO recommends a 5-day amoxicillin-based empiric treatment for community-acquired pneumonia 2

Clinical Monitoring:

• Clinical improvement should occur within 48-72 hours of starting therapy 1, 2
• If no improvement is seen within this timeframe, consider treatment failure, atypical pathogens, or complications 2
• Fever typically resolves within 24-48 hours for pneumococcal pneumonia, though cough may persist longer 1

Critical Considerations and Pitfalls

When to Use High-Dose Regimen:

• Children <2 years old 1
• Recent antibiotic exposure within the past 30 days 1
• Children attending daycare 1
• Areas with >10% penicillin-resistant S. pneumoniae 1
• Severe infections requiring hospitalization 1

Alternative Agents:

• For β-lactamase-producing organisms (H. influenzae, M. catarrhalis), use amoxicillin-clavulanate at 90 mg/kg/day of the amoxicillin component 1
• For non-anaphylactic penicillin allergy, use second- or third-generation cephalosporins (cefdinir, cefuroxime) 1
• For type I hypersensitivity reactions, azithromycin or other macrolides may be considered, though these are less effective against resistant pneumococci 3

Common Pitfalls:

• Avoid underdosing, which can lead to treatment failure and promote antimicrobial resistance 2
• Be aware that amoxicillin dosing recommendations have increased over time due to increasing pneumococcal resistance 2
• Recent evidence shows treatment failure and recurrence were lower for amoxicillin than for other agents, supporting its continued use as first-line therapy 5