Drug Interactions Corner

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CYP 3A4 Inhibitor–Inhaled Corticosteroid Interaction

KEY POINT

Potent inhibitors of the cytochrome P-450 (CYP) 3A4 isoenzyme can produce systemic adverse effects from some corticosteroids when they are administered via oral inhalation.

SOURCES

Lexi-Interacts information in Lexi-Comp monographs on corticosteroids (orally inhaled), antifungal agents (imidazole) and protease inhibitors. Available to APhA members in the Drug Information Center of www.pharmacist.com.

Raaska K et al. Plasma concentrations of inhaled budesonide and its effects on plasma cortisol are increased by the cytochrome P4503A4 inhibitor itraconazole. Clin Pharmacol Ther. 2002;72:362–9.