Further studies of the effects of inhaled glucocorticoids on pituitary-adrenal function in healthy adults.

We compared the effects of increasing doses of beclomethasone dipropionate (BDP) and fluocortin butylester (FCB) on several indices of pituitary-adrenal function in healthy adult subjects. Significant depression of urinary free cortisol excretion and the response to metyrapone was seen only at the highest dose (1600 mg/day) of BDP. This depression was not reflected by frequent measurement of the serum cortisol concentration. FCB used well in excess of its presumed therapeutic dose range showed no evidence of any effect on pituitary-adrenal function. These results confirm that at high doses BDP causes pituitary adrenal suppression. Differences from studies showing reduced adrenal function in children on BDP doses of 400 to 800 mg/day probably reflect differences in the dose per kilogram of body weight. Since the use of FCB was not accompanied by any adverse side effects or evidence of reduced pituitary-adrenal function, it may be a variable alternative for asthmatics who require high doses of inhaled glucocorticoid.