What is the therapeutic dose of co-amoxiclav (amoxicillin/clavulanic acid)?

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Co-Amoxiclav Therapeutic Dosing

For adults with respiratory tract infections, co-amoxiclav 875 mg/125 mg twice daily is the recommended therapeutic dose, while more severe infections may require 2000 mg/125 mg twice daily. 1, 2, 3

Adult Dosing Regimens

Standard Dosing

  • 500 mg/125 mg every 8 hours or 875 mg/125 mg every 12 hours for mild-to-moderate infections 2, 3
  • The 875/125 mg twice daily formulation is specifically recommended for respiratory infections including acute bacterial rhinosinusitis, community-acquired pneumonia, and acute exacerbations of chronic bronchitis 2
  • For more severe infections and respiratory tract infections, use 875 mg/125 mg every 12 hours or 500 mg/125 mg every 8 hours 3

High-Dose Formulations

  • 2000 mg/125 mg twice daily (pharmacokinetically enhanced formulation) is recommended when antibiotic resistance is likely, including recent antibiotic use, healthcare contact, prior treatment failure, or high community prevalence of resistant bacteria 1
  • This high-dose regimen achieves adequate serum concentrations to eradicate penicillin-resistant Streptococcus pneumoniae with amoxicillin MICs up to 4-8 mg/L 4, 5
  • Consider higher doses for moderate-to-severe infections (frontal/sphenoidal sinusitis), patients with comorbidities, immunocompromised status, or age >65 years 1

Duration of Therapy

  • 5-7 days for uncomplicated acute bacterial rhinosinusitis in adults 4, 2
  • 7-10 days for respiratory infections generally 1
  • 10-14 days for sinusitis or until symptomatically improved for 7 days 1
  • 3-7 days for uncomplicated urinary tract infections 1

Pediatric Dosing

Standard Pediatric Regimens

  • 45 mg/kg/day every 12 hours or 40 mg/kg/day every 8 hours for more severe infections in children ≥12 weeks 1
  • 25 mg/kg/day every 12 hours or 20 mg/kg/day every 8 hours for less severe infections in children ≥12 weeks 1
  • Children weighing ≥40 kg should be dosed according to adult recommendations 3

High-Dose Pediatric Formulation

  • 90 mg/kg/day of amoxicillin with 6.4 mg/kg/day of clavulanate in two divided doses for acute bacterial rhinosinusitis and resistant infections 4, 1
  • This high-dose regimen is recommended for children with recent antimicrobial use (past 4-6 weeks) or moderate disease 4
  • 10-14 days duration is recommended for children with acute bacterial rhinosinusitis (longer than adults) 4

Critical Dosing Considerations

Formulation Warnings

  • Do NOT substitute two 250 mg/125 mg tablets for one 500 mg/125 mg tablet - this results in excessive clavulanate dosing (250 mg vs 125 mg) 2, 3
  • Both 250 mg/125 mg and 500 mg/125 mg tablets contain the same amount of clavulanic acid (125 mg), making them non-interchangeable 3
  • The 250 mg/125 mg tablet should not be used in pediatric patients until they weigh at least 40 kg 3

Administration

  • Administer at the start of a meal to enhance clavulanate absorption and minimize gastrointestinal intolerance 3
  • May be taken without regard to meals, though absorption is optimized with food 3

Renal Impairment Adjustments

  • GFR <30 mL/min: Do not use 875 mg/125 mg formulation 3
  • GFR 10-30 mL/min: Use 500 mg/125 mg or 250 mg/125 mg every 12 hours 3
  • GFR <10 mL/min: Use 500 mg/125 mg or 250 mg/125 mg every 24 hours 3
  • Hemodialysis patients: 500 mg/125 mg or 250 mg/125 mg every 24 hours, with additional dose during and at end of dialysis 3

Hepatic Impairment

  • Dose with caution and monitor hepatic function at regular intervals 3

Common Pitfalls

  • Avoid underdosing in areas with high penicillin-resistant S. pneumoniae prevalence - use high-dose formulations (2000 mg/125 mg twice daily for adults or 90 mg/kg/day for children) 4, 1
  • Evaluate clinical response within 48-72 hours of initiating therapy to determine need for alternative management 4, 1
  • Complete the full course regardless of clinical improvement to prevent treatment failure and resistance development 2
  • For severe infections with potential toxin-producing organisms, co-amoxiclav alone may be insufficient 4

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References

Guideline

Amoxicillin-Clavulanate Dosage and Administration

Praxis Medical Insights: Practical Summaries of Clinical Guidelines, 2025

Guideline

Amoxiclav Dosing Guidelines for Adults

Praxis Medical Insights: Practical Summaries of Clinical Guidelines, 2025

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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