Fluconazole

Triazole·Infectious Diseases - Antifungals

Mucosal/Systemic Candidiasis, Cryptococcal meningitis

PBSANTIFUNGALDiflucan, Dizole50 mgS4+1

Max Dose

800 mg/day

Half-life

30 h

CYP Inhibitor

POTENT

QTc Risk

HIGH

Rapid Summary

Overview

Highly bioavailable triazole antifungal. Excellent against Candida albicans and Cryptococcus. Lacks coverage against Aspergillus or Candida krusei/glabrata.

Maximum Dose

Max 800 mg/day (Loading doses in severe cryptococcal meningitis). Standard max is 400 mg/day.

Clinical Focus

Potent inhibitor of CYP2C9 and CYP3A4. Massive interaction risk with Warfarin, Statins, and DOACs.

Bottom Line

Fluconazole is the first-line systemic antifungal for candidiasis with excellent oral bioavailability, but is a potent CYP2C19/3A4 inhibitor with significant drug interactions including warfarin.

Formulation & Access

Brand Names

Diflucan, Dizole

Oral Routes

Capsules (50 mg, 100 mg, 150 mg, 200 mg).

Parenteral

Infusion bags (200 mg/100 mL) for IV use.

Prescribing & PBS

Pharmacy Medicine (S3) for 150mg single dose. Prescription (S4) for others.

Indications & Use

Primary

PBSTGA

Mucosal/Systemic Candidiasis, Cryptococcal meningitis.

Clinical Place

First-line for susceptible Candida. Exceptional CNS penetration makes it the maintenance drug of choice for fungal meningitis.

Quick reference

Class & Role

Triazole — Highly bioavailable triazole antifungal.

Route / Formulation

Capsules (50 mg, 100 mg, 150 mg, 200 mg). (Diflucan, Dizole)

Usual Dose & Max

PO 150 mg STAT single dose. Max 800 mg/day (Loading doses in severe cryptococcal meningitis). Standard max is 400 mg/day.

Key Indication Doses

Vaginal Candidiasis: PO 150 mg STAT single dose. Oropharyngeal/Esophageal Thrush: PO 200 mg load, then 100-200 mg OD for 7-14 days. Invasive Candidiasis: IV / PO 800 mg load, then 400 mg OD. Renal Impairment: Halve the maintenance dose if eGFR < 50.

Best Uses

Fluconazole is the first-line systemic antifungal for candidiasis with excellent oral bioavailability, but is a potent CYP2C19/3A4 inhibitor with significant drug interactions including warfarin.

Avoid / Cautions

Co-administration with other strong QTc prolonging drugs (e.g., Erythromycin, Amiodarone) or drugs metabolized by CYP3A4 that cause fatal toxicity (e.g., Colchicine). Pregnancy Category D (High doses are teratogenic. Single 150mg dose is debated but often avoided).

Key Risks

Hepatic: Transaminitis, rare severe hepatic toxicity/failure. Cardiovascular: QTc prolongation, Torsades de Pointes. Gastrointestinal: Nausea, abdominal pain, diarrhea.

Key Interactions

Warfarin. Fluconazole shuts down CYP2C9, causing Warfarin levels to skyrocket. INR will spike dangerously. Halve the Warfarin dose and monitor tightly. Statins (increased rhabdomyolysis), Phenytoin (toxicity), DOACs (bleeding).

Monitoring

Baseline and routine LFTs (hepatic toxicity) and U&E (reduce dose in CKD). ECG for QTc assessment if combining with other psych/cardiac drugs.

Clinical Pearl

Fluconazole is brilliant for Candida albicans (common thrush). However, Candida glabrata and Candida krusei are intrinsically resistant. If a severely ill ICU patient is growing Candida in the blood, start an Echinocandin (Caspofungin) until species is identified.

Access

Diflucan, Dizole50 mg

Brand: Diflucan, Dizole
Formulation: Capsules (50 mg, 100 mg, 150 mg, 200 mg)

Fluconazole

Triazole·Infectious Diseases - Antifungals

Mucosal/Systemic Candidiasis, Cryptococcal meningitis

PBSANTIFUNGALDiflucan, Dizole50 mgS4+1

Max Dose

800 mg/day

Half-life

30 h

CYP Inhibitor

POTENT

QTc Risk

HIGH

Rapid Summary

Overview

Highly bioavailable triazole antifungal. Excellent against Candida albicans and Cryptococcus. Lacks coverage against Aspergillus or Candida krusei/glabrata.

Maximum Dose

Max 800 mg/day (Loading doses in severe cryptococcal meningitis). Standard max is 400 mg/day.

Clinical Focus

Potent inhibitor of CYP2C9 and CYP3A4. Massive interaction risk with Warfarin, Statins, and DOACs.

Bottom Line

Fluconazole is the first-line systemic antifungal for candidiasis with excellent oral bioavailability, but is a potent CYP2C19/3A4 inhibitor with significant drug interactions including warfarin.

Formulation & Access

Brand Names

Diflucan, Dizole

Oral Routes

Capsules (50 mg, 100 mg, 150 mg, 200 mg).

Parenteral

Infusion bags (200 mg/100 mL) for IV use.

Prescribing & PBS

Pharmacy Medicine (S3) for 150mg single dose. Prescription (S4) for others.

Indications & Use

Primary

PBSTGA

Mucosal/Systemic Candidiasis, Cryptococcal meningitis.

Clinical Place

First-line for susceptible Candida. Exceptional CNS penetration makes it the maintenance drug of choice for fungal meningitis.

Quick reference

Class & Role

Triazole — Highly bioavailable triazole antifungal.

Route / Formulation

Capsules (50 mg, 100 mg, 150 mg, 200 mg). (Diflucan, Dizole)

Usual Dose & Max

PO 150 mg STAT single dose. Max 800 mg/day (Loading doses in severe cryptococcal meningitis). Standard max is 400 mg/day.

Key Indication Doses

Best Uses

Fluconazole is the first-line systemic antifungal for candidiasis with excellent oral bioavailability, but is a potent CYP2C19/3A4 inhibitor with significant drug interactions including warfarin.

Avoid / Cautions

Key Risks

Hepatic: Transaminitis, rare severe hepatic toxicity/failure. Cardiovascular: QTc prolongation, Torsades de Pointes. Gastrointestinal: Nausea, abdominal pain, diarrhea.

Key Interactions

Monitoring

Baseline and routine LFTs (hepatic toxicity) and U&E (reduce dose in CKD). ECG for QTc assessment if combining with other psych/cardiac drugs.

Clinical Pearl

Access

Diflucan, Dizole50 mg

Brand: Diflucan, Dizole
Formulation: Capsules (50 mg, 100 mg, 150 mg, 200 mg)