What is the recommended fluconazole dose for an adult with Candida urinary tract infection, and how should it be adjusted for impaired renal function?

Fluconazole Dosing for Candida Urinary Tract Infections

Recommended Dosing by Clinical Presentation

For symptomatic Candida cystitis in adults with normal renal function, fluconazole 200 mg daily for 14 days is the standard treatment for fluconazole-susceptible organisms. 1, 2, 3

Asymptomatic Candiduria

• Do not treat asymptomatic candiduria in most patients – treatment is indicated only for high-risk groups including neutropenic patients, very low birth weight infants (<1500g), or patients undergoing urologic procedures 1, 2
• Remove indwelling urinary catheters immediately – this alone resolves candiduria in approximately 50% of cases and is the single most important intervention 1, 2
• If treatment is required (pre-operative suppression in high-risk patients), use fluconazole 200 mg daily for 14 days 1

Symptomatic Cystitis (Lower UTI)

• Fluconazole 200 mg daily for 14 days for fluconazole-susceptible species 1, 2, 3
• The FDA label indicates doses of 50-200 mg daily have been used, though guidelines favor 200 mg 4
• Some evidence suggests 7 days may be adequate, with one recent study showing no difference in clinical success between 7-day and 14-day courses (93.1% vs 93.3%), though 14 days remains the guideline recommendation 5

Pyelonephritis (Upper UTI)

• Fluconazole 200-400 mg daily for 14 days for fluconazole-susceptible organisms 1, 2, 3
• Higher doses (400 mg) are preferred for more severe upper tract infections 2, 6
• Consider adding flucytosine for severe cases or potentially resistant organisms 1

Renal Dose Adjustments

For patients with creatinine clearance <50 mL/min, reduce the maintenance dose by 50% after giving a full loading dose. 4

Specific Adjustments by Renal Function

• CrCl >50 mL/min: No adjustment needed – use standard 200 mg daily 4
• CrCl ≤50 mL/min (not on dialysis): Give loading dose of 200 mg, then 100 mg daily (50% reduction) 7, 4
• Hemodialysis patients: Give 200 mg after each hemodialysis session (not daily dosing) 7, 2, 4
• Continuous renal replacement therapy (CRRT): Higher doses may be needed – consider 800 mg daily based on recent pharmacokinetic data showing increased clearance 8

The FDA label provides clear guidance: after an initial loading dose, patients with CrCl ≤50 mL/min should receive 50% of the recommended dose, and hemodialysis patients should receive 100% of the dose after each dialysis session 4

Species-Specific Considerations

Always obtain species identification and susceptibility testing before finalizing treatment, as not all Candida species are fluconazole-susceptible. 2, 3

Fluconazole-Susceptible Species (C. albicans, C. parapsilosis, C. tropicalis)

• Use standard fluconazole dosing as outlined above 2, 3

Fluconazole-Resistant C. glabrata

• Amphotericin B deoxycholate 0.3-0.6 mg/kg daily for 1-7 days, OR 1, 3
• Oral flucytosine 25 mg/kg four times daily for 7-10 days 1, 3

C. krusei (Intrinsically Fluconazole-Resistant)

• Amphotericin B deoxycholate 0.3-0.6 mg/kg daily for 1-7 days 1, 3

Critical Pitfalls to Avoid

• Never continue indwelling catheters during treatment – this is the most common cause of treatment failure and significantly reduces cure rates 2
• Never assume all yeast is fluconazole-susceptible – C. glabrata has variable susceptibility and C. krusei is intrinsically resistant 2, 3
• Never use standard daily dosing in hemodialysis patients – fluconazole must be given after each dialysis session to maintain therapeutic levels 7, 2
• Never treat asymptomatic candiduria reflexively – this leads to unnecessary antifungal exposure and resistance development 2
• Never use lipid formulations of amphotericin B for UTI – these formulations have reduced renal excretion and theoretically lower urinary concentrations 1

Special Clinical Scenarios

Fungal Balls or Obstructive Uropathy

• Surgical intervention is required in addition to antifungal therapy 1, 2
• Medical therapy alone will fail without removal of obstruction 1

Neutropenic Patients

• Treat as candidemia, not isolated UTI – these patients require systemic antifungal therapy at higher doses (400-800 mg daily) 2, 3

Monitoring and Follow-Up

• Verify clinical response within 3-5 days – if no improvement, repeat cultures to assess for fluconazole resistance, particularly with C. glabrata 2
• Assess for urinary tract obstruction or fungal balls if treatment fails, as these require surgical intervention 2