In Reply We agree with Dr Schreuder and colleagues about the importance of the drug interaction between cyclosporine and itraconazole and the necessity of strict therapeutic drug monitoring of cyclosporine.
It is well known that periodic therapeutic drug monitoring is necessary when cyclosporine is administered. The therapeutically effective blood concentration of cyclosporine is narrow, and there are many foods and medicines that influence cyclosporine metabolism, including grapefruit and other citrus fruits, cola beverages, St John’s wort, calcium antagonists, macrolide antibiotics, human immunodeficiency virus protease inhibitors, estrogen and progestogen hormone preparations, and azole antifungals.
Hotta M, Ota M. Drug-Drug Interactions in Treatment Using Azole Antifungal Agents—Reply. JAMA. 2016;315(23):2622–2623. doi:10.1001/jama.2016.3826