Comparison of Inhaled Corticosteroids: An Update

H William Kelly, PharmD


The Annals of Pharmacotherapy. 2009;43(3):519-527. 

In This Article

Drug Interactions

An addition to the new dosing tables for inhaled corticosteroids is the warning concerning potentially clinically significant drug interactions with a number of the inhaled corticosteroids and potent inhibitors of CYP3A4 isozymes (eg, ketoconazole, itraconazole, ritonavir).[1] The interaction is most likely due to increased oral bioavailability, as it is affected to a greater extent than systemic elimination for high hepatic extraction drugs and that CYP3A4 isozymes are in abundance in the intestinal lining, facilitating the high first-pass effect.[55] Numerous reports of clinically significant Cushing's syndrome and adrenal insufficiency in both children and adults have appeared in the literature secondary to the combination of fluticasone propionate or budesonide with a CYP3A4 inhibitor.[56,57,58,59] The vast majority of these patients were receiving high doses of the inhaled corticosteroid prior to beginning the inhibitor. Both mometasone furoate and des-ciclesonide plasma concentrations significantly increase with concomitant ketoconazole administration. Flunisolide and beclomethasone dipropionate are also metabolized by CYP3A4. Thus, clinicians should be aware of the need to use lower doses of most inhaled corticosteroids with coadministration of CYP3A4 inhibitors.


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