What is the appropriate dose of Augmentin (amoxicillin‑clavulanate) for a child weighing 11.25 kg?

Augmentin Dosing for an 11.25 kg Child

For an 11.25 kg child, administer 506 mg of amoxicillin twice daily (1012 mg/day total), which corresponds to approximately 5.6 mL of the 90 mg/mL (600 mg/5 mL) high-dose suspension twice daily. This provides the guideline-recommended 90 mg/kg/day high-dose regimen that is strongly indicated for most pediatric infections requiring amoxicillin-clavulanate. 1, 2

High-Dose Regimen: The Standard of Care

• The American Academy of Pediatrics and Infectious Diseases Society of America recommend 90 mg/kg/day of the amoxicillin component with 6.4 mg/kg/day of clavulanate, divided into two doses every 12 hours, as the preferred regimen for most pediatric infections. 1, 2

• This high-dose formulation provides a 14:1 ratio of amoxicillin to clavulanate, which significantly reduces diarrhea compared to older formulations while maintaining superior efficacy against resistant organisms. 1, 2

• The maximum single dose is 2000 mg of amoxicillin per administration, regardless of weight—well above what this child requires. 2

When High-Dose Therapy Is Indicated

High-dose amoxicillin-clavulanate (90 mg/kg/day) should be used when ANY of the following risk factors are present: 1, 2

• Age < 2 years (this 11.25 kg child likely falls into this category based on typical weight-for-age) 1, 2
• Daycare attendance 1, 2
• Antibiotic use within the preceding 30 days 1, 2
• Incomplete Haemophilus influenzae type b vaccination (< 3 doses) 1, 2
• Geographic area with > 10% penicillin-resistant Streptococcus pneumoniae 1, 2
• Moderate to severe illness at presentation 1, 2
• Concurrent purulent acute otitis media 1, 2
• Prior treatment failure with amoxicillin alone 1, 2

Infection-Specific Dosing

Acute Otitis Media

• 90 mg/kg/day in two divided doses for 10 days, providing 90-92% predicted clinical efficacy against penicillin-resistant S. pneumoniae. 1, 2
• Children under 2 years with AOM specifically require the high-dose formulation. 1

Community-Acquired Pneumonia

• For children < 5 years: 90 mg/kg/day in two divided doses for 10 days. 1, 2
• If H. influenzae type b vaccination is incomplete or concurrent purulent otitis media is present, use 80-90 mg/kg/day of the amoxicillin component. 1

Acute Bacterial Rhinosinusitis

• 90 mg/kg/day in two divided doses for 10-14 days, strongly recommended as first-line therapy. 1, 2

Practical Administration

• Use the 600 mg/5 mL (90 mg/mL) high-dose suspension to deliver the appropriate dose in a reasonable volume. 1
• For this 11.25 kg child: 90 mg/kg/day × 11.25 kg = 1012.5 mg/day ÷ 2 doses = 506 mg per dose = 5.6 mL twice daily. 1, 2
• Always verify the suspension concentration before dispensing (125/31 mg/mL vs 250/62 mg/mL vs 600/42.9 mg/5 mL) to avoid potentially dangerous dosing errors. 1, 2

Treatment Duration and Monitoring

• Standard treatment duration is 10 days for most respiratory infections. 1, 2
• Clinical improvement should be evident within 48-72 hours; if no improvement or worsening occurs, reevaluate the diagnosis, consider atypical pathogens, assess for complications, or change antibiotics. 1, 2
• Continue therapy for an additional 7 days after the child becomes free of signs and symptoms. 1

Age Restriction

• Augmentin may be safely initiated in children ≥ 3 months of age when bacterial infection is suspected or confirmed. 1
• Safety and efficacy data are robust for children ≥ 3 months but remain limited for younger infants, who should receive intravenous therapy (ampicillin + gentamicin or cefotaxime) for serious bacterial infections. 1

Adverse Effects

• Diarrhea occurs in approximately 25% of treated children (vs 15% with placebo), and diaper dermatitis in 51% (vs 35% with placebo). 1
• The 14:1 amoxicillin-to-clavulanate ratio in the high-dose formulation causes significantly less diarrhea than older preparations while maintaining efficacy. 1, 2
• Recent evidence suggests that even lower clavulanate concentrations (2.85-3.2 mg/kg/day) may reduce side effects further without compromising clinical efficacy, though this is not yet standard practice. 3

Critical Pitfalls to Avoid

• Using age-based dosing when high-dose weight-based therapy is indicated leads to treatment failure with resistant organisms. 1
• Subtherapeutic doses fail to achieve adequate serum and tissue concentrations to overcome even susceptible organisms and promote antimicrobial resistance. 1
• Underdosing is the most common prescribing error—always calculate based on actual weight, not age brackets, for serious infections. 1, 2

Renal Impairment

• If this child has established renal insufficiency, prolong the dosing interval according to creatinine clearance to avoid drug accumulation, as both amoxicillin and clavulanate are renally eliminated. 1, 2