What is the proper use and dosage of Amoxiclav (amoxicillin/clavulanic acid) for treating bacterial infections?

Amoxicillin-Clavulanate (Amoxiclav): Proper Use and Dosing

Amoxicillin-clavulanate is a first-line broad-spectrum antibiotic for respiratory tract infections, skin infections, and animal bites, with dosing that varies significantly based on infection severity, patient age, and local resistance patterns.

Adult Dosing Recommendations

Standard Dosing for Mild-to-Moderate Infections

• 500 mg/125 mg every 8 hours or 875 mg/125 mg every 12 hours for most uncomplicated infections 1
• For skin and soft tissue infections, animal/human bites: 875 mg/125 mg twice daily 2, 3
• Duration typically 7-10 days for most infections 3

High-Dose Regimen for Severe or Resistant Infections

• 2000 mg/125 mg (2 g/125 mg) twice daily for respiratory infections with risk factors 2, 3
• High-dose is indicated when patients have: recent antibiotic use within 30 days, treatment failure, close contact with daycare children, smoking exposure, age >65 years, immunocompromised status, moderate-to-severe infection, or frontal/sphenoidal sinusitis 3

Infection-Specific Dosing

Acute Bacterial Rhinosinusitis (ABRS):

• Amoxicillin-clavulanate is preferred over amoxicillin alone (strong recommendation in children, weak in adults) 2
• High-dose formulation for patients with risk factors 2
• Duration: 5-7 days in adults (as effective as 10 days) 2, 3

Skin and Soft Tissue Infections:

• 875 mg/125 mg twice daily for impetigo, cellulitis, or animal bites 2
• Provides coverage for beta-lactamase producing Staphylococcus aureus (MSSA) 3

Pediatric Dosing Recommendations

Standard Dosing

• 45 mg/kg/day of amoxicillin component with 6.4 mg/kg/day of clavulanate, divided into 2 doses for uncomplicated infections 3
• Alternative: 25 mg/kg/day in 2 divided doses or 20 mg/kg/day in 3 divided doses for mild infections 2

High-Dose Regimen

• 80-90 mg/kg/day of amoxicillin with 6.4 mg/kg/day of clavulanate, divided into 2 doses 2, 3
• The 14:1 ratio formulation causes less diarrhea than other preparations 3

Indications for High-Dose in Children

• Age <2 years 3
• Daycare attendance 3
• Recent antibiotic use within 30 days 3
• Areas with >10% penicillin-resistant Streptococcus pneumoniae 3
• Concurrent conjunctivitis (provides Moraxella catarrhalis coverage) 3
• Pneumonia not responding to amoxicillin alone 3

Duration in Children

• 10-14 days for acute bacterial rhinosinusitis 2, 3
• 5 days for non-severe pneumonia 3
• At least 10 days for Streptococcus pyogenes infections to prevent rheumatic fever 4

Critical Dosing Considerations

Renal Impairment

• GFR 10-30 mL/min: 500 mg/125 mg or 250 mg/125 mg every 12 hours 1, 4
• GFR <10 mL/min: 500 mg/125 mg or 250 mg/125 mg every 24 hours 1, 4
• Hemodialysis: Additional dose during and after dialysis 1, 4
• Do NOT use 875 mg/125 mg formulation if GFR <30 mL/min 1, 4

Important Formulation Warning

• Two 250 mg/125 mg tablets are NOT equivalent to one 500 mg/125 mg tablet (same clavulanate content) 1
• This is a common prescribing error that must be avoided

Administration Guidelines

• Take at the start of meals to enhance clavulanate absorption and minimize gastrointestinal side effects 1, 4
• Oral suspension must be shaken well before use and discarded after 14 days 4
• Refrigeration of suspension is preferable but not required 4

Antimicrobial Spectrum and Resistance

• Provides coverage for beta-lactamase producing Haemophilus influenzae, Moraxella catarrhalis, and MSSA 2, 3, 5
• Effective against penicillin-susceptible and intermediate S. pneumoniae 5, 6
• High-dose formulation extends coverage to penicillin-resistant S. pneumoniae (MIC ≤2-4 mg/L) 5, 6
• Routine MRSA coverage is NOT recommended for initial empiric therapy of ABRS 2

Common Pitfalls to Avoid

• Do not substitute formulations: Different ratios of amoxicillin to clavulanate are not interchangeable 1
• Avoid underdosing in resistant infections: Use high-dose formulations when risk factors are present 2, 3
• Do not use 875 mg formulation in severe renal impairment (GFR <30 mL/min) 1, 4
• Ensure adequate treatment duration: 5-7 days in adults is sufficient for ABRS, but children require 10-14 days 2, 3

Adverse Effects

• Most common: mild gastrointestinal disturbances, particularly diarrhea 7, 8
• Diarrhea is less frequent with twice-daily versus three-times-daily dosing 6
• Nausea and vomiting can be minimized by taking with food 1, 8
• Overall well-tolerated with low incidence of serious adverse events 6