What are the contraindications for fluconazole?

Contraindications for Fluconazole

Fluconazole is absolutely contraindicated in patients with known hypersensitivity to fluconazole or any of its excipients, and when coadministered with drugs that prolong the QT interval and are metabolized via CYP3A4 (such as erythromycin, pimozide, and quinidine). 1

Absolute Contraindications

Hypersensitivity Reactions

• Known hypersensitivity to fluconazole or any excipient is an absolute contraindication 1
• Cross-hypersensitivity between fluconazole and other azole antifungals is possible, though specific data are limited; exercise caution when prescribing to patients with documented azole hypersensitivity 1
• Desensitization protocols exist for patients who require fluconazole when no adequate alternative is available, though this should only be attempted in controlled settings 2

Drug-Drug Interactions with QT-Prolonging Agents

• Coadministration with CYP3A4-metabolized drugs that prolong QT interval (erythromycin, pimozide, quinidine) is absolutely contraindicated 1
• Fluconazole itself may cause QT interval prolongation, particularly when combined with other QT-prolonging medications including fluoroquinolones, macrolides, ondansetron, and certain chemotherapies like nilotinib 3, 4
• The risk of QT prolongation is substantially increased with combination therapy involving multiple QT-prolonging agents 3, 4

Relative Contraindications and High-Risk Scenarios

Cardiac Dysfunction

• While itraconazole (not fluconazole) is specifically contraindicated in patients with decreased cardiac ejection fraction or congestive heart failure due to negative inotropic properties, fluconazole's QT-prolonging effects warrant extreme caution in patients with underlying cardiac disease 3, 4

Pregnancy Considerations

• Chronic high-dose fluconazole (≥400 mg daily) during pregnancy is associated with "fluconazole embryopathy"—a syndrome of craniosynostosis, characteristic facies, digital synostosis, and limb contractures 3
• Amphotericin B should replace high-dose fluconazole during the first trimester for invasive or refractory esophageal candidal infections 3
• Single-dose episodic treatment (150 mg) has not been associated with birth defects, but chronic use at any dose should be avoided during pregnancy 3
• Systemic azole prophylaxis (primary or secondary) should not be initiated during pregnancy, and existing prophylactic azoles should be discontinued when pregnancy is confirmed 3

Specific Clinical Scenarios Requiring Alternative Agents

• For candidemia in pregnant women, amphotericin B deoxycholate is the treatment of choice, not fluconazole 4
• Avoid fluconazole as initial therapy for suspected endocardial or CNS candidiasis; use fungicidal agents like amphotericin B instead 4
• Do not use fluconazole in moderately-to-severely ill patients with recent azole exposure or high risk of C. glabrata or C. krusei infection; echinocandins are preferred 4
• Fluconazole has no activity against C. krusei and variable activity against C. glabrata—confirm susceptibility before use or choose an alternative agent 4

Critical Drug Interaction Warnings

Cytochrome P450 Enzyme Inhibition

• Fluconazole inhibits CYP2C9 and CYP2C19 enzymes with high interpatient variability due to genetic polymorphisms 3, 4
• CYP3A4 inhibition can increase plasma concentrations of coadministered drugs, potentially causing serious adverse events 3, 4
• Both addition and withdrawal of fluconazole can result in either increased uptake of other drugs or subtherapeutic exposure, potentially leading to transplant rejection or graft-versus-host disease 3
• Specific interactions include increased levels of cyclosporine, phenytoin, oral hypoglycemics, and warfarin; rifampin decreases fluconazole clearance 5, 6

Common Pitfalls to Avoid

• Do not initiate fluconazole for fungemia without knowing the Candida species, as C. krusei and C. glabrata may be resistant 3
• Do not use fluconazole in patients with severe renal impairment without appropriate dose adjustment, as the drug is primarily eliminated unchanged in the urine 5, 6
• Avoid prescribing fluconazole to patients currently taking multiple QT-prolonging medications without careful cardiac monitoring and risk-benefit assessment 3, 4