Interactions with other medicines and products
Interaction Scope
Medicinal product categories with documented interactions: Drugs that prolong the QT interval and are metabolized via CYP3A4, Anticoagulants (Coumarin-type), HMG-CoA Reductase Inhibitors, Immunosuppressant drugs, Oral Contraceptives, and Anticonvulsants.
Specific interacting medicines (if explicitly listed): Pimozide, Quinidine, and Erythromycin are listed as contraindicated. Warfarin, Cyclosporine, Carbamazepine, Rifampin, and Hydrochlorothiazide are also specifically cited in regulatory documents.
Mechanistic basis of interactions (only if stated in label): Fluconazole is a strong inhibitor of CYP2C19 and a moderate inhibitor of CYP2C9 and CYP3A4. It may contribute to QT interval prolongation, which is a pharmacodynamic interaction.
Timing-based interaction rules (if applicable): No mandatory timing or separation windows are explicitly stated in the regulatory text.
Population-specific interaction notes (if applicable): The drug's pharmacokinetics are markedly affected by reduced renal function. Higher pharmacokinetic parameters are observed in elderly subjects.
Interaction-related restrictions: Coadministration with Pimozide, Quinidine, and Erythromycin is absolutely contraindicated. Monitoring of prothrombin time is recommended during concurrent use with Coumarin-type anticoagulants.
Interaction Classifications (High-Level)
Interaction severity classification (as defined in official documents): Absolute Contraindication applies to several specific co-administered drugs. Clinically Significant / Increased Exposure Risk applies to numerous substrates of CYP2C9, CYP2C19, and CYP3A4.
Interaction-context constraints (as defined in official documents): The drug's absorption is not affected by food; it may be taken without regard to meals.
Resulting interaction structure
Official interaction statements:
- Fluconazole is a strong inhibitor of CYP2C19 and a moderate inhibitor of CYP2C9 and CYP3A4.
- Coadministration with drugs known to prolong the QT interval, such as Pimozide and Quinidine, is absolutely contraindicated.
- Coadministration with Hydrochlorothiazide increases fluconazole plasma concentrations by 40%, while coadministration with Rifampin reduces fluconazole AUC by 23%.
Connection to the overall interaction profile (4 sentences):
The official interaction structure is defined by fluconazole’s classification as a CYP enzyme inhibitor, primarily affecting CYP2C19, CYP2C9, and CYP3A4. This mechanism results in the increased exposure of many co-administered medicinal products, which often requires specific restrictions or cautions. The profile also highlights additive pharmacodynamic risks, such as the absolute contraindication for co-administration with certain QT-prolonging agents. The drug's exposure is unaffected by food but is significantly sensitive to reduced renal function.