What is the recommended dose of Augmentin (amoxicillin/clavulanate) for a patient with impaired renal function, specifically a creatinine level of 2.04 and a glomerular filtration rate (GFR) of 33?

Augmentin Dosing in Renal Impairment (GFR 33 mL/min)

For a patient with creatinine 2.04 mg/dL and GFR 33 mL/min, reduce Augmentin to 250-500 mg every 12 hours or use the standard dose (500-875 mg) every 24 hours, depending on infection severity.

Rationale for Dose Adjustment

Your patient has Stage 3b chronic kidney disease (GFR 30-44 mL/min) based on the provided parameters 1. Both amoxicillin and clavulanic acid are primarily renally cleared and require dose modification to prevent drug accumulation and toxicity 2, 3.

Pharmacokinetic Considerations

• Amoxicillin clearance is significantly reduced when creatinine clearance falls below 30-50 mL/min, with total body clearance decreasing proportionally to renal function 2
• The elimination half-life of amoxicillin extends from approximately 1 hour in normal renal function to 13.6 hours in end-stage renal disease 3
• Clavulanic acid similarly demonstrates reduced clearance (43.6 mL/min vs normal 150-200 mL/min) with a terminal half-life of 3.05 hours in severe renal impairment 3
• Non-renal clearance mechanisms are also impaired in chronic kidney disease, further reducing drug elimination 3

Specific Dosing Recommendations

For Moderate Infections (UTI, Sinusitis, Bronchitis)

• Augmentin 250-500 mg every 12 hours 2, 3
• Alternative: 500 mg every 24 hours for less severe infections

For Severe Infections (Pneumonia, Complicated Infections)

• Augmentin 500-875 mg every 12-24 hours 3, 4
• Monitor closely for adverse effects and consider therapeutic drug monitoring if available

Critical Dosing Principles

• Never use the 875 mg twice daily formulation in this patient—excessive accumulation will occur 2
• Dose immediately after dialysis if the patient progresses to hemodialysis, as both components are significantly dialyzable (fractional removal 0.64-0.65) 3
• The extended dosing interval (every 12-24 hours rather than every 8 hours) is essential because standard dosing would lead to drug accumulation 2

Monitoring Requirements

Essential Parameters to Track

• Serum creatinine should be monitored every 2-3 days during treatment, as acute kidney injury can progress in this population 1
• Watch for signs of drug accumulation including gastrointestinal disturbances (diarrhea, nausea), which occur more frequently with clavulanic acid accumulation 5
• Monitor for crystalluria, particularly if using higher doses, as amoxicillin can precipitate in concentrated urine 2

Risk of Dialysis Requirement

• Patients with baseline creatinine >2.0 mg/dL have a 25-38% risk of requiring dialysis during acute illness or after procedures 6
• If dialysis becomes necessary, supplement with 250-500 mg post-dialysis to replace the 64% of drug removed during a 4-hour session 3

Common Pitfalls to Avoid

Do not rely on standard dosing charts that only provide adjustments for creatinine clearance <30 mL/min—your patient at GFR 33 is in the borderline zone requiring dose reduction 1, 2.

Avoid using serum creatinine alone to guide dosing in elderly patients or those with reduced muscle mass, as it underestimates the degree of renal impairment 7. Calculate actual creatinine clearance using Cockcroft-Gault equation 1.

Do not assume normal hepatic function—patients with chronic kidney disease often have some degree of hepatic impairment that further reduces non-renal clearance of both amoxicillin and clavulanic acid 3.

Clinical Efficacy in Renal Impairment

Despite dose reduction, Augmentin maintains excellent efficacy in renal insufficiency patients. Studies demonstrate 100% prevention of wound infections in renal failure patients receiving prophylactic amoxicillin-clavulanate, with bactericidal concentrations maintained for up to 20 hours post-operatively even in dialysis patients 4. The success rate for treating resistant urinary pathogens remains approximately 70% even with adjusted dosing 5.