What is the appropriate Augmentin (amoxicillin‑clavulanate) dosing regimen for a child weighing 18.2 kg with normal renal function and no penicillin allergy?

Augmentin Dosing for an 18.2 kg Child

For a child weighing 18.2 kg with normal renal function, administer Augmentin 400 mg/5 mL oral suspension at 4 mL twice daily (providing approximately 45 mg/kg/day of amoxicillin) for standard infections, or 8 mL twice daily (providing approximately 90 mg/kg/day) for severe infections or suspected drug-resistant pathogens. 1, 2

Weight-Based Calculation

• At 18.2 kg, this child falls well within the pediatric weight-based dosing range (under 40 kg threshold where adult dosing begins) 1, 3, 2
• The FDA-approved dosing for children ≥3 months is based on the amoxicillin component: 25-45 mg/kg/day for standard infections or 45-90 mg/kg/day for severe infections, divided every 12 hours 2

Standard Dosing Regimen (Mild-to-Moderate Infections)

• For uncomplicated respiratory infections, skin infections, or urinary tract infections: Use 45 mg/kg/day divided into 2 doses 1, 2
• For an 18.2 kg child: 18.2 kg × 45 mg/kg/day = 819 mg/day total amoxicillin 1
• Using the 400 mg/5 mL suspension: approximately 4 mL twice daily (providing 320 mg per dose, 640 mg/day total) 1, 2
• This provides adequate coverage for most susceptible pathogens including Streptococcus pneumoniae, Haemophilus influenzae, and Streptococcus pyogenes 3

High-Dose Regimen (Severe Infections or Drug-Resistant Pathogens)

• For community-acquired pneumonia, recent antibiotic exposure (within 4-6 weeks), daycare attendance, or treatment failure: Use 90 mg/kg/day divided into 2 doses 4, 1, 3
• For an 18.2 kg child: 18.2 kg × 90 mg/kg/day = 1,638 mg/day total amoxicillin 1
• Using the 400 mg/5 mL suspension: approximately 8 mL twice daily (providing 640 mg per dose, 1,280 mg/day total) 1, 2
• The high-dose regimen provides optimal coverage against penicillin-resistant Streptococcus pneumoniae and β-lactamase-producing organisms 1, 3

Infection-Specific Considerations

• For acute otitis media: The American Academy of Pediatrics recommends 10 days of treatment duration, with high-dose regimen (90 mg/kg/day) preferred if the child has received antibiotics within the past 4-6 weeks 1, 2
• For community-acquired pneumonia: The Infectious Diseases Society of America recommends the high-dose regimen (90 mg/kg/day) for children with suspected bacterial pneumonia, particularly in areas with >10% penicillin-resistant S. pneumoniae 4, 1
• For sinusitis: Standard dosing (45 mg/kg/day) is appropriate for children ≥2 years without risk factors, while high-dose regimen is recommended for children <2 years, in daycare, or with recent antibiotic use 3

Treatment Duration and Monitoring

• Standard treatment duration is 7-10 days for most infections, with pneumonia specifically requiring 10 days 1, 3
• Children on appropriate therapy should demonstrate clinical improvement within 48-72 hours; if no improvement occurs, reevaluation and further investigation are necessary 1, 3
• Complete the full course of antibiotics as prescribed, even if symptoms improve before completion 1

Critical Pitfalls to Avoid

• Never use standard adult dosing for pediatric patients under 40 kg - always calculate based on weight in mg/kg 1, 5
• Do not underdose when drug-resistant pathogens are suspected - use the 90 mg/kg/day regimen for recent antibiotic exposure, daycare attendance, or treatment failure 1, 3
• Avoid substituting different formulations without adjusting for clavulanate content - the 250 mg/125 mg tablet contains different clavulanate ratios than chewable formulations and cannot be directly substituted 2
• Always record patient weight in kilograms on prescriptions to enable pharmacists to verify appropriate dosing 6

Administration Guidance

• Augmentin may be taken without regard to meals, but absorption of clavulanate is enhanced when administered at the start of a meal 2
• To minimize gastrointestinal intolerance (particularly diarrhea), administer at the start of a meal 2
• The every 12-hour regimen is recommended over every 8-hour dosing as it is associated with significantly less diarrhea 2, 7