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.