Systemic Bioavailability and Potency of High-Dose Inhaled Corticosteroids: Outcome
The incorrect use of a spacer device may leave more of the activated dose within the spacer and less available for systemic absorption through the lung. An inadequately primed spacer with high static electricity, multiple actuations, and a delay between actuation and inhalation all reduce drug delivery to the lung. Washing and polishing a spacer device may also affect its performance. These caveats may explain the conflicting data produced by previous studies, most of which were conducted before the optimal method of use of large volume spacers had been established. In the present study, all precautions were taken to ensure maximum drug delivery to the lung from the large volume spacer, and the impressive cortisol suppression caused by fluticasone and beclomethasone (given by large volume spacer) confirm that this objective was achieved.
Our study is in agreement with most of the previous studies in showing that the large volume spacer device reduces the systemic absorption of inhaled steroids. This is an unexpected result, as one would expect the spacer device to increase lung deposition (the main source of systemic absorption) while reducing GI deposition, which is a less important source of systemic absorption.2 There are few studies comparing the clinical benefit of inhaled steroids given by MDI spacer compared with MDI alone. If the increased deposition that was shown in laboratory studies could be confirmed in clinical practice, the therapeutic index of inhaled steroids would be enhanced by the use of a large volume spacer (increased benefit with decreased systemic effect). buy ventolin inhaler
Nebulized budesonide produced no fall in 9:00 am plasma cortisol level. It is likely that this is due to the inefficiency of nebulized delivery systems compared with MDIs and spacer devices. Wilson and Lipworth had a similar result (no suppression of cortisol) using a different nebulizer system (Ventstream; Medic-Aid). However, it has been demonstrated recently that budesonide given by a novel nebulizer (Pari Inhaler Boy; Pari; Starnberg, Germany), which activates only during inspiration, will achieve similar clinical effects (and cortisol suppression) to the same dose of budesonide given by MDI spacer. This implies that nebulized budes-onide given by conventional nebulizers is likely to be less efficient than the same dose of budesonide given by MDI spacer.