In an adult who completed intravenous therapy for a necrotic foot ulcer and now requires oral Augmentin (amoxicillin‑clavulanate) with impaired renal function, should the dosing be adjusted for different stages of chronic kidney disease?

Augmentin Dosing in Chronic Kidney Disease

Yes, Augmentin (amoxicillin-clavulanate) requires dose adjustment in patients with severe renal impairment (GFR <30 mL/min), but not in mild to moderate renal dysfunction. 1

Dosing Algorithm by Renal Function Stage

Stage 1-3 CKD (GFR ≥30 mL/min)

• No dose adjustment required – Use standard dosing regimens (e.g., 875 mg/125 mg every 12 hours or 500 mg/125 mg every 8 hours) 1
• The FDA label explicitly states that dosage adjustment is "usually required" only in patients with severe renal impairment 1

Stage 4-5 CKD (GFR <30 mL/min)

• Dose adjustment is mandatory 1
• Reduce the dosing frequency rather than the individual dose to maintain adequate peak concentrations 2
• Recommended regimen: 500 mg/125 mg every 12 hours for moderate infections, or 500 mg/125 mg every 24 hours for severe impairment (GFR <10 mL/min) 2, 3
• Administer the dose after hemodialysis on dialysis days, as approximately 40% of amoxicillin is removed during a dialysis session 2, 3

Critical Pharmacokinetic Consideration

The amoxicillin and clavulanate components accumulate differently in renal failure, which creates a dosing challenge 2:

• Amoxicillin clearance decreases dramatically as GFR falls – its elimination is primarily renal 2, 3
• Clavulanate clearance decreases less severely because it has significant non-renal metabolism 2
• This differential accumulation means the ratio of amoxicillin to clavulanate increases substantially in renal failure (from 4.9:1 at normal GFR to 14.7:1 in dialysis patients) 2
• Clinical implication: Extending the dosing interval (rather than reducing the dose) prevents amoxicillin toxicity while maintaining adequate clavulanate levels 2

Monitoring Requirements in Renal Impairment

• Assess renal function before initiating therapy – Calculate GFR or creatinine clearance to determine if dose adjustment is needed 1
• Monitor for adverse effects more closely in elderly patients with renal impairment, as they are at higher risk 1
• Reassess renal function during treatment if clinical deterioration occurs, particularly in patients with diabetic foot infections who may have fluctuating renal function 4, 5

Common Pitfalls to Avoid

• Do not reduce the individual dose size in renal failure – instead, extend the dosing interval to maintain concentration-dependent bacterial killing 2
• Do not assume dose adjustment is needed for mild-moderate CKD (GFR 30-89 mL/min) – standard dosing is appropriate and effective in this population 1, 4
• Do not give the dose before hemodialysis – always administer after dialysis to avoid premature drug removal 2, 3
• Be cautious in elderly patients even with mild renal impairment, as age-related decreases in renal function may not be reflected in serum creatinine due to reduced muscle mass 1

Special Consideration for Diabetic Foot Infections

In your specific clinical scenario (post-IV therapy for necrotic foot ulcer transitioning to oral Augmentin):

• Augmentin has demonstrated efficacy in diabetic foot infections even in patients with renal impairment 4, 5
• If GFR ≥30 mL/min: Use standard oral dosing (875 mg/125 mg twice daily or 500 mg/125 mg three times daily) 4, 5
• If GFR <30 mL/min: Reduce to 500 mg/125 mg every 12-24 hours depending on severity of renal impairment 1, 2
• Renal function itself is a variable that influences treatment efficacy in diabetic foot infections, so close monitoring is essential 4