Oral Dosage of Fluconazole (Diflucan) for Fungal Infections
The recommended oral dosage of fluconazole (Diflucan) for treating fungal infections varies by infection type, with standard dosing of 100-400 mg daily, typically starting with a loading dose of twice the daily dose on the first day of treatment. 1
Dosing by Infection Type
Oropharyngeal Candidiasis
- Loading dose: 200 mg on first day
- Maintenance: 100 mg once daily for at least 2 weeks 1
- Treatment should continue for at least 2 weeks to prevent relapse
Esophageal Candidiasis
- Loading dose: 200 mg on first day
- Maintenance: 100 mg once daily 1
- Doses up to 400 mg/day may be used based on clinical response
- Minimum treatment duration: 3 weeks and at least 2 weeks following symptom resolution
Vaginal Candidiasis
- Single oral dose: 150 mg 1
Systemic Candida Infections (including candidemia, disseminated candidiasis, pneumonia)
- Doses up to 400 mg daily 1
- Optimal duration not firmly established
Cryptococcal Meningitis
- Loading dose: 400 mg on first day
- Maintenance: 200-400 mg once daily 1
- Treatment duration: 10-12 weeks after CSF becomes culture negative
- Suppression therapy in AIDS patients: 200 mg once daily
Urinary Tract Infections and Peritonitis
- 50-200 mg daily 1
Special Considerations
Renal Impairment
- Dosage adjustment required for patients with creatinine clearance <50 mL/min 2
- For invasive candidiasis, standard dosing includes loading dose of 800 mg (12 mg/kg), followed by 400 mg (6 mg/kg) daily
Prophylaxis in Bone Marrow Transplantation
- 400 mg once daily 1
- Start several days before anticipated onset of neutropenia
- Continue for 7 days after neutrophil count exceeds 1000 cells/mm³
Administration Considerations
- Oral absorption is rapid and nearly complete (approximately 90% bioavailability) 2
- Food consumption, gastric pH, or disease state do not affect absorption
- Fluconazole achieves excellent penetration into CSF and vitreous body (at least 50% of serum concentrations) 2
- Urine concentrations are 10-20 times higher than serum concentrations
Treatment Duration
- Treatment should continue until clinical parameters or laboratory tests indicate that active fungal infection has subsided 1
- Inadequate treatment duration may lead to recurrence
- Patients with AIDS and cryptococcal meningitis or recurrent oropharyngeal candidiasis usually require maintenance therapy to prevent relapse
Potential Pitfalls
- Drug interactions with agents metabolized by cytochrome P450 enzymes should be carefully monitored 2
- Prolonged use of azoles increases risk of resistance, especially in immunocompromised patients 3
- Liver function tests should be monitored if treatment extends beyond 7-10 days 3
- For refractory cases, alternative antifungal agents or higher doses may be necessary
Fluconazole's excellent bioavailability, CSF penetration, and once-daily dosing make it a convenient and effective option for treating various fungal infections, with dosing tailored to the specific infection site and severity.