What is the recommended dose of fluconazole (antifungal medication) for various fungal infections?

Fluconazole Dosing for Fungal Infections

For systemic candidiasis, administer a loading dose of 800 mg (12 mg/kg) on day 1, followed by 400 mg (6 mg/kg) daily maintenance dosing, continuing for 2 weeks after the first negative blood culture and symptom resolution. 1, 2

Systemic Candida Infections

• Loading dose: 800 mg (12 mg/kg) on day 1 is recommended by the American College of Microbiology and IDSA to achieve therapeutic levels rapidly 1, 2
• Maintenance dose: 400 mg (6 mg/kg) daily for candidemia and disseminated candidiasis 1, 2, 3, 4
• Treatment duration: Continue for 2 weeks after first negative blood culture and resolution of symptoms 1
• In neutropenic patients: Extend treatment for 2-3 weeks after neutropenia resolution (neutrophil count >1000 cells/mm³) and negative cultures 1
• Central venous catheter removal is strongly recommended for patients with systemic candidiasis 2

Oropharyngeal Candidiasis

• Mild disease: Topical agents are preferred first-line 3
• Moderate to severe disease: Fluconazole 100-200 mg daily for 7-14 days 3
• Standard regimen: 200 mg loading dose on day 1, then 100 mg once daily for at least 2 weeks 2, 4
• Relapse rates are high (40%) in immunocompromised patients, requiring maintenance therapy in AIDS patients 4, 5

Esophageal Candidiasis

• Standard dose: 200 mg on day 1, followed by 100 mg once daily 4
• Higher doses: Up to 400 mg daily may be used based on clinical response 3, 4
• Treatment duration: Minimum 14-21 days and at least 2 weeks following symptom resolution 2, 3, 4

Urinary Tract Infections

• Symptomatic cystitis: 200 mg (3 mg/kg) daily for 14 days 1, 2, 3
• Pyelonephritis: 200-400 mg (3-6 mg/kg) daily for 14 days 1, 3
• Lower doses (50-200 mg daily) have been used in small studies for Candida UTIs 4

CNS Candidiasis

• Dose range: 400-800 mg (6-12 mg/kg) daily for patients unable to tolerate amphotericin B 1, 2
• Treatment duration: Continue until all signs, symptoms, CSF abnormalities, and radiologic findings resolve 1

Cryptococcal Meningitis

• Acute treatment: 400 mg on day 1, followed by 200-400 mg once daily 4
• Treatment duration: 10-12 weeks after CSF becomes culture negative 4
• Maintenance therapy in AIDS patients: 200 mg once daily to prevent relapse 4

Vaginal Candidiasis

• Single-dose therapy: 150 mg as a single oral dose 4, 6
• Efficacy: Provides 74.7-84% clinical cure rate with excellent tolerability 5, 6

Chronic Disseminated Candidiasis

• Dose: 400 mg (6 mg/kg) daily for stable patients 2
• Duration: Continue until lesions resolve, typically 3-6 months 2

Prophylaxis in Bone Marrow Transplant

• Dose: 400 mg once daily 4
• Timing: Start several days before anticipated neutropenia (neutrophils <500 cells/mm³) and continue for 7 days after neutrophil count rises above 1000 cells/mm³ 4

Pediatric Dosing Conversions

• 3 mg/kg ≈ 100 mg adult dose 1, 2
• 6 mg/kg ≈ 200 mg adult dose 1
• 12 mg/kg ≈ 400 mg adult dose 1
• Maximum daily dose: 600 mg in children; 1600 mg maximum in adults to avoid neurological toxicity 4, 5

Critical Species-Specific Considerations

Fluconazole has NO activity against Candida krusei and variable activity against C. glabrata—always confirm susceptibility before use. 1, 2, 3

• C. parapsilosis: Fluconazole is appropriate; consider switching from echinocandin if initially used 1
• C. glabrata: Use echinocandin or amphotericin B initially; only switch to fluconazole if susceptibility confirmed AND patient clinically improved 1
• C. krusei: Use echinocandin, amphotericin B, or voriconazole—fluconazole is NOT effective 1, 2

Common Pitfalls to Avoid

• Inadequate treatment duration leads to relapse—continue until clinical and laboratory parameters indicate complete resolution 1, 2
• Resistance development is particularly problematic in patients with recurrent or chronic infections 1
• Candida isolated from respiratory secretions usually represents colonization, not infection, and rarely requires treatment 3
• Oral and IV dosing are equivalent due to >93% bioavailability—use the same daily dose for both routes 4, 5
• Food, hypochlorhydria, and gastrointestinal resection do not affect absorption 5