From the FDA Drug Label
Dosage In Patients With Impaired Renal Function: Fluconazole is cleared primarily by renal excretion as unchanged drug. ... In patients with impaired renal function who will receive multiple doses of fluconazole tablets, an initial loading dose of 50 mg to 400 mg should be given After the loading dose, the daily dose (according to indication) should be based on the following table: Creatinine Clearance (mL/min) Recommended Dose (%)
50 100 ≤50 (no dialysis) 50 Hemodialysis 100% after each hemodialysis
The dose of fluconazole for a patient with Chronic Kidney Disease (CKD) to treat onychomycosis is not directly stated in the label. However, for patients with impaired renal function, the daily dose should be adjusted based on the creatinine clearance.
- For patients with creatinine clearance >50 mL/min, the recommended dose is 100%.
- For patients with creatinine clearance ≤50 mL/min (no dialysis), the recommended dose is 50%.
- For patients on hemodialysis, the recommended dose is 100% after each hemodialysis. Since the label does not provide a specific dose for onychomycosis, and the dose for this indication is not provided, the dose cannot be determined from the label 1.
From the Research
For patients with chronic kidney disease (CKD) requiring fluconazole to treat onychomycosis, the dosage should be adjusted based on the patient's creatinine clearance, with a recommended dose of 150 mg weekly for more than 6 months, as supported by the most recent study 2. The adjustment of fluconazole dosage in patients with CKD is crucial to prevent potential adverse effects such as hepatotoxicity, QT prolongation, and drug interactions. Key considerations for dosage adjustment include:
- For mild to moderate CKD (creatinine clearance 50-80 mL/min), the standard dose of 150-300 mg weekly can be maintained.
- For moderate to severe CKD (creatinine clearance 10-50 mL/min), the dose should be reduced by 50%, typically to 150 mg weekly.
- For patients with severe CKD (creatinine clearance <10 mL/min) or those on dialysis, the dose should be reduced by 50-75%, with 150 mg given every 7-14 days. It is essential to note that fluconazole is primarily eliminated through renal excretion, and impaired kidney function leads to drug accumulation, potentially causing adverse effects 3. Regular monitoring of liver function and potential drug interactions is essential during treatment, as emphasized in a recent study on the safety of oral antifungals for the treatment of onychomycosis 4. The treatment duration for onychomycosis typically ranges from 6-12 months for toenails and 3-6 months for fingernails, continuing until the infected nail has grown out completely. In terms of efficacy, fluconazole has been shown to be effective in treating onychomycosis, although it may be less effective than other antifungal agents such as terbinafine and itraconazole 5, 6.