What is the recommended dose of Augmentin (amoxicillin/clavulanate) for a 38kg child with appendicitis?

Augmentin Dosing for a 38kg Child with Appendicitis

For a 38kg child with appendicitis, Augmentin is not the recommended first-line antibiotic according to current guidelines; however, if used, the dose would be 45 mg/kg/day of the amoxicillin component divided every 12 hours (approximately 855 mg twice daily), administered intravenously initially at 100 mg/kg/day. 1

Why Augmentin is Not First-Line for Appendicitis

The Surgical Infection Society and Infectious Diseases Society of America guidelines for complicated intra-abdominal infections in children do not list ampicillin-sulbactam (Augmentin's IV equivalent) as a preferred regimen for complicated appendicitis. 1

Preferred regimens include: 1

• Piperacillin-tazobactam (200-300 mg/kg/day of piperacillin component every 6-8 hours)
• Carbapenems (ertapenem, meropenem, or imipenem)
• Advanced cephalosporins with metronidazole (ceftriaxone 50-75 mg/kg/day plus metronidazole 30-40 mg/kg/day)
• Aminoglycoside-based regimens

If Augmentin Must Be Used

Intravenous Dosing (Preferred Initial Route)

For complicated intra-abdominal infection including perforated appendicitis, the IV dose is 100 mg/kg/day of the amoxicillin component divided every 6 hours. 2, 3

For a 38kg child:

• Total daily dose: 3,800 mg/day
• Divided dose: 950 mg IV every 6 hours

This dosing was validated in prospective trials showing equivalent efficacy to triple-agent therapy (benzylpenicillin-netilmicin-metronidazole) for appendicular peritonitis in children. 2, 3

Transition to Oral Therapy

Once the patient has been afebrile for 48 hours, transition to oral amoxicillin-clavulanate at 50 mg/kg/day of the amoxicillin component. 2, 3

For a 38kg child:

• Total daily dose: 1,900 mg/day
• Divided dose: 950 mg orally twice daily

Duration of Therapy

The total duration of IV plus oral therapy should be at least 5 days. 2, 3 However, recent evidence suggests patients meeting discharge criteria with normal leukocyte counts may be safely discharged without completing oral antibiotics after adequate IV therapy. 4

Standard Pediatric Dosing Context

For reference, FDA-approved dosing for children ≥12 weeks with more severe infections is 45 mg/kg/day every 12 hours or 40 mg/kg/day every 8 hours based on the amoxicillin component. 5

For a 38kg child using standard dosing:

• 45 mg/kg/day regimen: 855 mg twice daily
• 40 mg/kg/day regimen: 507 mg three times daily

Children weighing ≥40 kg should be dosed according to adult recommendations (500 mg/125 mg every 8 hours or 875 mg/125 mg every 12 hours for severe infections). 5

Critical Caveats

• β-lactam antibiotic dosages should be maximized if undrained intra-abdominal abscesses may be present. 1
• Augmentin lacks adequate coverage for some resistant organisms commonly encountered in complicated intra-abdominal infections, which is why broader-spectrum agents are preferred. 1
• The 250 mg/125 mg tablets should not be used until the child weighs at least 40 kg due to different amoxicillin-to-clavulanic acid ratios. 5
• Monitor renal function as dose adjustments are required for renal impairment. 5

Practical Algorithm

1. If appendicitis is uncomplicated (non-perforated): Consider other antibiotics per institutional protocol
2. If appendicitis is complicated/perforated:
   • First choice: Use guideline-recommended regimens (piperacillin-tazobactam, carbapenem, or ceftriaxone/metronidazole) 1
   • If Augmentin must be used: Start IV at 100 mg/kg/day (950 mg every 6 hours for 38kg child) 2, 3
   • After 48 hours afebrile: Transition to oral 50 mg/kg/day (950 mg twice daily) 2, 3
   • Minimum duration: 5 days total therapy 2, 3
   • Consider early discontinuation if leukocyte count normalizes and patient meets discharge criteria 4