Adrenal suppression in asthmatic children receiving low-dose inhaled budesonide: comparison between dry powder inhaler and pressurized metered-dose inhaler attached to a spacer.

Background: Dry powder inhalers (DPI) have in recent years become a common mode for administration of inhaled corticosteroids for preventive therapy of asthma. Inhaled steroids delivered by DPI achieve increased lung deposition compared with pressurized metered-dose inhalers (pMDI), which is associated with increased therapeutic effect. This may be associated with increased systemic absorption.

Objective: The purpose of this study was to evaluate the prevalence of adrenal suppression in children using low-dose budesonide given by DPI, as compared with pMDI attached to a large-volume spacer device (pMDI + spacer).

Methods: In an open-labeled crossover study, 15 asthmatic children aged 5 to 15 years received 200 microg of inhaled budesonide twice daily by DPI (Turbuhaler, Astra, Draco AB, Lund, Sweden) and by pMDI + spacer, 1 month each, in a randomized order. Twenty-four-hour urine collections were performed at baseline and at the end of each of the 2 months of the study period, and urinary cortisol and creatinine were measured.

Results: Baseline urinary cortisol:creatinine was 0.038 +/- 0.012 microg/mg, similar in both groups. After 1 month of DPI therapy, urinary cortisol:creatinine was reduced by 27 +/- 16% to 0.028 +/- 0.012 microg/mg (P = 0.018). Urinary cortisol:creatinine after 1 month of pMDI + spacer therapy was similar to baseline 0.037 +/- 0.019 microg/mg (P = 0.78).

Conclusions: Treatment of asthmatic children with budesonide 400 microg daily given via a DPI for 1 month was associated with hypothalamic-pituitary-adrenal axis suppression. This effect was not observed with the same dose of budesonide administered via pMDI + spacer. This indicates that systemic absorption might be reduced with pMDI + spacer therapy.