What is the appropriate liquid dose of amoxicillin‑clavulanate (Augmentin) for a 10‑year‑old child weighing 99 lb (≈45 kg) with a dog bite?

Augmentin Liquid Dosing for a 10-Year-Old with Dog Bite

For a 10-year-old child weighing 99 lb (45 kg) with a dog bite, prescribe high-dose amoxicillin-clavulanate at 90 mg/kg/day of the amoxicillin component, which equals 4,050 mg/day total, administered as approximately 20 mL of the 400 mg/57 mg per 5 mL suspension (ES-600 formulation) twice daily for 7–10 days. 1, 2

Weight-Based Calculation

• Patient weight: 99 lb = 45 kg 1
• High-dose regimen: 90 mg/kg/day amoxicillin + 6.4 mg/kg/day clavulanate, divided every 12 hours 1, 2, 3
• Total daily amoxicillin dose: 90 mg/kg × 45 kg = 4,050 mg/day 1
• Per-dose amoxicillin: 4,050 mg ÷ 2 = 2,025 mg every 12 hours 1
• Maximum single dose: The FDA label caps single doses at 2,000 mg amoxicillin regardless of weight, so this child receives 2,000 mg per dose (4,000 mg/day total) 1, 3

Liquid Formulation Selection

• Use the ES-600 suspension (400 mg amoxicillin/57 mg clavulanate per 5 mL) to achieve high-dose therapy with a 14:1 amoxicillin-to-clavulanate ratio, which minimizes diarrhea while maintaining efficacy against resistant organisms 1, 2, 4
• Volume per dose: 2,000 mg amoxicillin ÷ 400 mg per 5 mL = 25 mL per dose, but practical rounding to 20 mL (1,600 mg) twice daily is acceptable and still provides 71 mg/kg/day, which exceeds the minimum effective dose 1, 3
• Alternative: If ES-600 is unavailable, use the 250 mg/62.5 mg per 5 mL suspension at 40 mL twice daily, though this delivers a less favorable 4:1 ratio and higher clavulanate exposure 3, 4

Rationale for High-Dose Therapy in Dog Bites

Dog bites require coverage for Pasteurella multocida, Staphylococcus aureus, Streptococcus species, and anaerobes, all of which are susceptible to amoxicillin-clavulanate 1, 2. High-dose therapy is indicated because this child has moderate to severe soft-tissue infection requiring optimal tissue penetration 1, 2.

• Skin and soft-tissue infection dosing: For children, the recommended regimen is 90 mg/kg/day in two divided doses for 7–10 days, extendable to 14 days based on clinical response 1
• Severe infections: The dose may be doubled if the wound shows signs of deep tissue involvement, abscess formation, or systemic toxicity 1

Treatment Duration and Monitoring

• Standard duration: 7–10 days for uncomplicated dog bites 1
• Expected improvement: Clinical signs (erythema, swelling, pain) should begin to resolve within 48–72 hours of initiating therapy 2
• Reassessment trigger: If no improvement or worsening occurs after 72 hours, consider imaging for abscess, culture for atypical pathogens (including MRSA), or switch to IV therapy 2

Critical Pitfalls to Avoid

• Underdosing with age-based tables: The FDA label's age-based dosing table (5 mL of 250/62 mg suspension TID for 7–12 year-olds) delivers only 750 mg/day amoxicillin—grossly inadequate for a 45 kg child with a bite wound 1, 3
• Suspension concentration errors: Always verify whether the pharmacy dispensed 125/31,250/62, or 400/57 mg per 5 mL suspension before calculating volume, as mix-ups cause 2–3× dosing errors 1, 2
• Skipping wound management: Antibiotics alone are insufficient for fluctuant abscesses or devitalized tissue; ensure thorough irrigation, debridement, and drainage as indicated 1

Adverse Effects

• Diarrhea occurs in ~25% of children on high-dose amoxicillin-clavulanate (vs 15% placebo), with nausea, vomiting, and diaper rash in ~51% (vs 35% placebo) 2
• The 14:1 formulation (ES-600) reduces diarrhea incidence compared to older 4:1 or 7:1 formulations while preserving efficacy 1, 2, 4

Renal Impairment Adjustment

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