Diflucan (fluconazole) is a systemic antifungal medication indicated for the treatment and prevention of various fungal infections. As a triazole antifungal agent, it works by inhibiting the synthesis of ergosterol, a critical component of fungal cell membranes, leading to cell death. This medication is available in oral and intravenous formulations, providing flexibility in administration based on clinical need and patient condition. Its broad-spectrum activity and favorable pharmacokinetic profile make it a cornerstone in antifungal therapy for both invasive and mucosal infections.

Features

• Active ingredient: Fluconazole 50 mg, 100 mg, 150 mg, or 200 mg tablets; 2 mg/mL or 10 mg/mL intravenous solution
• Mechanism: Inhibits fungal cytochrome P450-dependent enzyme lanosterol 14-α-demethylase
• Bioavailability: >90% following oral administration
• Half-life: Approximately 30 hours, allowing for once-daily dosing
• Protein binding: Low (11–12%), ensuring high tissue penetration
• Excretion: Primarily renal (80% unchanged in urine)
• FDA-approved for multiple indications including oropharyngeal, esophageal, and systemic candidiasis; cryptococcal meningitis; and prophylaxis in immunocompromised patients

Benefits

• Provides rapid symptomatic relief from fungal infections within 24–72 hours of initiation
• High oral bioavailability eliminates the need for intravenous administration in many cases, supporting outpatient treatment
• Demonstrated efficacy in both immunocompetent and immunocompromised hosts, including HIV/AIDS and oncology patients
• Prevents recurrence of cryptococcal meningitis in AIDS patients when used as maintenance therapy
• Single-dose regimen available for uncomplicated vulvovaginal candidiasis, enhancing adherence
• Well-tolerated profile with a low incidence of severe adverse effects compared to older antifungals

Common use

Diflucan is commonly prescribed for the treatment of oropharyngeal and esophageal candidiasis, particularly in patients with HIV/AIDS or those undergoing chemotherapy. It is also used for systemic candidiasis, including candidemia, disseminated candidiasis, and peritonitis. In cryptococcal meningitis, it serves as both acute therapy and maintenance treatment to prevent relapse. Prophylactically, it is employed to reduce the incidence of candidiasis in patients receiving bone marrow transplantation who are undergoing cytotoxic chemotherapy or radiation therapy. Off-label uses include treatment of fungal urinary tract infections, coccidioidomycosis, and onychomycosis, though efficacy may vary.

Dosage and direction

Dosage varies by indication and patient status. For oropharyngeal candidiasis: 200 mg on day one, then 100 mg once daily for at least 14 days. For esophageal candidiasis: 200 mg on day one, then 100 mg once daily; may increase to 400 mg daily if needed, with treatment continued for at least 21 days. For systemic candidiasis: 400 mg on day one, then 200 mg once daily; doses up to 400 mg/day may be used based on clinical response. For cryptococcal meningitis: 400 mg on day one, then 200–400 mg once daily for 10–12 weeks after cerebrospinal fluid becomes culture-negative. For vulvovaginal candidiasis: single 150 mg oral dose. Renal impairment requires dosage adjustment: if creatinine clearance <50 mL/min, reduce dose by 50%. Administration with food is optional as absorption is not affected.

Precautions

Use with caution in patients with hepatic impairment, as fluconazole is metabolized partially by the liver; monitor liver function tests periodically. Electrolyte imbalances, particularly hypokalemia, should be corrected prior to and during therapy. QT prolongation has been reported; avoid use in patients with known QT prolongation or concurrent use of other QT-prolonging drugs. Superinfections with non-susceptible fungi or bacteria may occur. Not recommended during pregnancy unless potential benefit justifies potential risk (Pregnancy Category D). Breastfeeding should be avoided unless clearly needed, as fluconazole is excreted in human milk.

Contraindications

Hypersensitivity to fluconazole, other azole antifungals, or any component of the formulation. Coadministration with cisapride, due to risk of serious cardiac arrhythmias. Use with terfenadine is contraindicated if fluconazole doses exceed 400 mg/day. Concomitant use with erythromycin or other drugs known to prolong QT interval and metabolized by CYP3A4. Severe hepatic impairment. Known history of torsades de pointes.

Possible side effect

Common side effects (≥1%) include headache, nausea, abdominal pain, diarrhea, rash, and elevated liver enzymes. Less frequently, vomiting, dyspepsia, dizziness, and taste perversion may occur. Serious side effects include hepatotoxicity (ranging from mild transaminase elevations to hepatic failure), anaphylaxis, QT prolongation, torsades de pointes, adrenal insufficiency, and severe cutaneous adverse reactions such as Stevens-Johnson syndrome. Alopecia and hypertriglyceridemia have been reported in long-term use.

Drug interaction

Fluconazole is a moderate inhibitor of CYP2C9 and CYP3A4 and may increase concentrations of drugs metabolized by these enzymes. Significant interactions include warfarin (increased prothrombin time), phenytoin, cyclosporine, tacrolimus, statins, sulfonylureas, and theophylline. Coadministration with rifampin reduces fluconazole concentrations by approximately 25%. Hydrochlorothiazide increases fluconazole concentrations by 40%. Avoid concurrent use with cisapride, pimozide, or quinidine due to arrhythmia risk.

Missed dose

If a dose is missed, take it as soon as remembered unless it is almost time for the next dose. Do not double the dose to make up for the missed one. Resume the regular dosing schedule. For once-daily regimens, if missed by more than 12 hours, wait until the next scheduled dose.

Overdose

Symptoms may include hallucinations, paranoid behavior, and nausea. There is no specific antidote. Treatment is supportive and symptomatic. Gastric lavage may be considered if ingestion was recent. Hemodialysis reduces fluconazole plasma concentrations by approximately 50% over 3 hours and may be used in overdose cases, particularly in renal impairment.

Storage

Store tablets at controlled room temperature (20–25°C or 68–77°F); excursions permitted to 15–30°C (59–86°F). Keep in original container, tightly closed, and protect from moisture and light. Intravenous solution should be stored at 5–30°C (41–86°F); do not freeze. Keep out of reach of children and pets.

Disclaimer

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition or medication. Do not disregard professional medical advice or delay in seeking it because of something you have read here.

Reviews

Clinical studies demonstrate high efficacy of Diflucan, with cure rates of 80–90% in oropharyngeal candidiasis and 60–80% in cryptococcal meningitis. Patients often report rapid symptom relief, particularly in vulvovaginal candidiasis. Some criticisms include emerging resistance in Candida species, particularly C. glabrata and C. krusei, and drug interactions limiting use in polypharmacy patients. Overall, it remains a first-line treatment for many fungal infections due to its reliability, tolerability, and convenience.