Effects of long-term inhaled corticosteroids on adrenal function in patients with asthma

Background: Inhaled corticosteroids (ICSs) are effective asthma controllers, but long-term use could lead to adverse effects. Objective: To examine adrenal responsiveness of patients with persistent asthma treated with long-term ICSs. Methods: Morning plasma cortisol levels before and 30 minutes after adrenocorticotropic hormone (ACTH) (1 μg intravenously) stimulation were compared. Primary end points included mean prestimulation and poststimulation cortisol levels; secondary end points included morning cortisol level of 5 μg/dL or less, post-ACTH stimulation cortisol level of 18 μg/dL or less, and/or a net change of 7 μg/dL or less from baseline. Results: A total of 103 asthmatic patients (29 in the triamcinolone acetonide group, 18 in the flunisolide group, 45 in the fluticasone propionate group, and 11 in the oral corticosteroids group [positive controls]) completed the study. Mean daily ICS doses and durations were as follows: triamcinolone acetonide: 448 μg for 36 months; flunisolide: 1,181 μg for 41 months; and fluticasone propionate: 745 μg for 19 months. Eleven of 30 patients taking high-dose ICSs (10 of 28 taking fluticasone propionate and 1 of 2 taking flunisolide) had both low morning cortisol levels and abnormal post-ACTH stimulation cortisol levels. Few patients taking lower doses of any ICS had abnormal results. Conclusions: Patients who require long-term treatment with high-dose ICSs may have abnormal morning plasma cortisol levels and reduced responsiveness to ACTH stimulation. Careful monitoring of adrenal function should be considered in such patients.