[Cushing's syndrome with inhaled corticosteroid: Drug interactions to avoid]

Cushing's syndrome is an iatrogenic event occurring during co-administration of inhaled corticosteroids and potent inhibitors of P450 cytochromes. We report the clinical case of a 29-year-old woman with a past history of asthma treated with inhaled fluticasone propionate (FP), chronic pulmonary aspergillosis and allergic bronchopulmonary aspergillosis (ABPA) treated with itraconazole (ITZ), and Mycobacterium xenopi infection treated with moxifloxacin (MXF), ethambutol (EMB) and clarithromycin (CLR). Four months after initiation of antibiotic and antifungal medication, the patient contracted Cushing's syndrome. Its etiology consisted in interaction between FP, ITZ and CLR, which led to pronouncedly increased corticosteroid concentrations in circulating plasma cells. Following on the one hand cessation of FP and ITZ and on the other hand hydrocortisone supplementation, evolution was favorable. Several cases of iatrogenic Cushing's syndrome induced by co-administration of FP and potent CYP3A4 inhibitors have been reported in the literature. If possible, FP should be avoided in patients being treated with CYP3A4 inhibitors. Due to its differing physicochemical properties, beclometasone may be considered as the safest therapeutic alternative.