What is the appropriate dosing of Augmentin (amoxicillin‑clavulanate) for an adult with end‑stage renal disease on hemodialysis who has a fistula‑site abscess?

Augmentin Dosing for Fistula-Site Abscess in ESRD on Hemodialysis

For an adult with end-stage renal disease on hemodialysis presenting with a fistula-site abscess, administer Augmentin 500/125 mg (amoxicillin/clavulanate) orally after each dialysis session, three times weekly, with a supplemental dose immediately following dialysis to replace drug removed during the session.

Dosing Rationale

Core Dosing Principles for ESRD

The fundamental approach to antibiotic dosing in hemodialysis patients requires maintaining standard individual doses while extending the dosing interval, rather than reducing the dose size 1. This principle is critical because:

• Both amoxicillin and clavulanic acid are significantly removed by hemodialysis, with fractional drug removal of 0.64 and 0.65 respectively during a 4-hour dialysis session 2
• Hemodialysis clearance for amoxicillin is 77.1 ml/min and for clavulanic acid is 92.8 ml/min, substantially increasing total drug clearance during dialysis 2
• Reducing individual doses leads to subtherapeutic peak concentrations and treatment failure, particularly for concentration-dependent antibiotics 1

Timing of Administration

Always administer Augmentin immediately after dialysis sessions to prevent premature drug removal and ensure adequate therapeutic levels 1, 3. On non-dialysis days in the interdialytic period, no supplemental dosing is typically needed given the extended half-lives in ESRD:

• Amoxicillin half-life extends to 13.6 hours on non-dialysis days (versus 2.30 hours during dialysis) 2
• Clavulanic acid half-life extends to 3.05 hours on non-dialysis days (versus 1.19 hours during dialysis) 2

Specific Dosing Recommendations

Standard Regimen

• Dose: 500/125 mg (one standard-strength tablet) orally
• Frequency: Three times weekly, immediately after each dialysis session
• Duration: 7-14 days depending on clinical response and abscess characteristics

Alternative Higher-Dose Regimen (for severe infection)

• Dose: 875/125 mg orally or 1.2 g IV
• Frequency: After each dialysis session (three times weekly)
• Rationale: The intravenous formulation has been specifically studied in ESRD patients at 1.2 g doses with demonstrated safety 2

Important Caveats and Monitoring

Accumulation Risk

Both amoxicillin and clavulanic acid demonstrate reduced non-renal clearance in ESRD patients compared to normal subjects, suggesting some degree of hepatic impairment and potential for drug accumulation 2. This necessitates:

• Close monitoring for adverse effects, particularly gastrointestinal symptoms
• Consideration of dose reduction if toxicity develops, though this should be balanced against maintaining therapeutic efficacy

Supplemental Dosing Post-Dialysis

Because approximately 64-65% of both components are removed during a 4-hour dialysis session 2, 4, a supplemental dose equal to the regular dose should be given immediately after dialysis 5. This replaces drug removed during the session and maintains therapeutic levels until the next dialysis.

Clinical Efficacy Considerations

Augmentin has demonstrated 68-86% clinical success rates in urogenital infections even in patients with chronic renal insufficiency 6. For fistula-site abscesses, adequate source control (drainage if indicated) remains essential alongside antibiotic therapy.

Drug Characteristics Favoring Dialyzability

Augmentin is substantially cleared by hemodialysis because both components have 5:

• Low molecular weight
• Reduced protein binding
• Limited distribution volume (14.9 L for amoxicillin, 11.0 L for clavulanic acid) 2

This pharmacokinetic profile mandates post-dialysis supplementation to maintain efficacy.