Lung deposition of budesonide from a pressurized metered-dose inhaler attached to a spacer

The absolute systemic availability and pulmonary deposition of budesonide i nhaled from a pressurized metered-dose inhaler (pMDI) attached to a Nebuhal er(R) spacer was determined in 15 healthy subjects, The study was of an open cross-over design. Each subject randomly received three single doses of budesonide on separate days: 0.5 mg given intravenous ly and 1.0 mg (0.2 mg x 5) by inhalation from a pMDI with a Nebuhaler(R), w ith or without concomitant oral charcoal intake to prevent gastrointestinal absorption. Charcoal intake did not significantly. effect the systemic availability or deposition of budesonide, The systemic availability was 36+/-14% (metered d ose, mean+/-SD) with charcoal and 35+/-10% without. The pulmonary depositio n was 36+/-14% with charcoal and 34+/-11% without, Erroneous administration , in which the canister was shaken only before the first of the five actuat ions. halved the systemic availability. In conclusion, the pulmonary deposition of budesonide from a pressurized me tered-dose inhaler with Nebuhaler(R) is high ender optimum conditions, The small discrepancy between the systemic availability and pulmonary depositio n indicates that the contribution from deposition in the oropharynx and sub sequent absorption from the gastrointestinal tract is negligible, The marke d reduction in the systemic availability of budesonide with the unshaken ca nisters confirms that the performance of a pressurized metered-dose inhaler is very much dependent on proper handling.