What is the standard dose and duration of Diflucan (fluconazole) for an adult patient with normal renal function and no significant hepatic impairment?

Standard Fluconazole Dosing for Adults

For adults with normal renal function, fluconazole dosing is indication-specific, ranging from a single 150 mg dose for uncomplicated vaginal candidiasis to 200-800 mg daily for invasive infections, with treatment duration varying from one day to several weeks depending on the infection type and clinical response. 1, 2

Dosing by Specific Indication

Vaginal Candidiasis

• Single dose of 150 mg orally for uncomplicated infection 2, 3, 4
• Clinical cure rates exceed 90% with this single-dose regimen 2, 4
• For recurrent vulvovaginal candidiasis: 150 mg weekly for 6 months after initial control 1, 2

Oropharyngeal Candidiasis

• Mild disease: 100 mg daily for 7-14 days 1
• Alternative for mild disease: Clotrimazole troches 10 mg 5 times daily for 7-14 days 1
• Moderate to severe disease: 100-200 mg daily for 7-14 days 1, 2
• Loading dose approach: 200 mg on day 1, then 100 mg daily for at least 2 weeks 2, 5

Esophageal Candidiasis

• 200-400 mg daily for 14-21 days 1, 2
• Minimum treatment duration is 3 weeks and at least 2 weeks following resolution of symptoms 1
• For patients unable to tolerate oral therapy: IV fluconazole 400 mg (6 mg/kg) daily OR an echinocandin 1

Invasive Candidiasis/Candidemia

• Loading dose of 800 mg (12 mg/kg) on day 1, followed by 400 mg (6 mg/kg) daily 1, 2, 3
• Treatment duration: 14 days after first negative blood culture and resolution of signs/symptoms 1, 2
• Catheter removal is strongly recommended 1
• Ophthalmological examination recommended for all patients 1

Urinary Tract Infections

• Asymptomatic candiduria: No treatment usually indicated unless high-risk patient (neutropenic, undergoing urologic procedures) 1
• Symptomatic cystitis: 200 mg (3 mg/kg) daily for 2 weeks 1, 5
• Pyelonephritis: 200-400 mg (3-6 mg/kg) daily for 2 weeks 1, 5

Cryptococcal Meningitis

• Acute treatment: 400-800 mg daily 2, 3
• Suppression of relapse in AIDS patients: 200 mg once daily 3
• Treatment duration for initial therapy: 10-12 weeks after CSF becomes culture negative 3

Critical Dosing Adjustments for Renal Impairment

Normal Renal Function (CrCl >50 mL/min)

• No dose adjustment required 6, 2, 3
• Use standard dosing based on indication 6

Impaired Renal Function (CrCl ≤50 mL/min)

• Administer full loading dose on day 1 6, 3
• Reduce maintenance dose to 50% starting day 2 6, 5, 3
• Example: For invasive candidiasis, give 800 mg loading dose, then 400 mg daily becomes 200 mg daily 6

Hemodialysis Patients

• 100% of recommended dose after each hemodialysis session 6, 3
• On non-dialysis days: Use reduced dose according to creatinine clearance 6, 3

Key Pharmacokinetic Properties

• Oral bioavailability is approximately 90%, making oral and IV dosing equivalent 2, 7
• Not affected by food, gastric pH, or hypochlorhydria 2, 7
• CSF concentrations reach 50-89% of serum levels, ideal for CNS infections 2, 7
• Urine concentrations reach 10-20 times serum levels 2
• Half-life: 22-32 hours in healthy individuals, 37 hours in patients with AIDS 7, 8
• Low protein binding (11%) 7, 8

Critical Pitfalls to Avoid

• Do not use fluconazole for suspected C. glabrata or C. krusei infections due to reduced susceptibility; use echinocandins instead 2
• Avoid azole empiric therapy in patients who received azole prophylaxis; switch to echinocandin 1, 2
• Do not use fluconazole prophylaxis in immunocompetent patients on antibiotics as it promotes resistance without proven benefit 2
• Maximum daily dose of 1600 mg to avoid neurological toxicity 7

Important Drug Interactions

• Fluconazole inhibits CYP3A4 and CYP2C9 6
• Monitor carefully when used with: cyclosporine, phenytoin, oral hypoglycemics, warfarin, and antiretroviral drugs 6, 8
• Rifampin decreases fluconazole clearance 8

Monitoring Recommendations

• Monitor renal function regularly during therapy as changes in CrCl may necessitate dose adjustments 6
• For cryptococcal infections: Document CSF culture clearance after 2 weeks of induction therapy 6