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Fluticasone-azole interaction — GPhC CRA MCQ

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HardRespiratory TherapeuticsFluticasone-azole interactionGPhC CRA

A 45-year-old woman with moderate persistent asthma is taking fluticasone/salmeterol 250/50 inhaler (Seretide Accuhaler) one puff twice daily. She has been prescribed a short course of itraconazole 200 mg daily for a fungal nail infection. What is the most important concern?

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Correct answer: B — Itraconazole inhibits CYP3A4 and may significantly increase systemic fluticasone exposure leading to adrenal suppression

Itraconazole is a potent CYP3A4 inhibitor. Fluticasone is extensively metabolised by CYP3A4, and concurrent use with itraconazole can dramatically increase systemic fluticasone exposure, leading to Cushing's syndrome and adrenal suppression. The BNF flags this as a significant interaction. The prescriber should be contacted to consider an alternative antifungal (such as terbinafine for dermatophyte infections) or an alternative ICS with less CYP3A4 dependence.

Reference: BNF Drug Interactions; MHRA Drug Safety Update