Particle size measurements for the Space-Chamber metered dose inhaler holding chamber compared with aerochamber and metered dose inhaler alone

The particle size distribution of aerosols inhaled at 28.3 L/min from a new holding chamber, the Space-Chamber (Medical Developments, Melbourne, Australia), is characterized for salbutamol (100 mu g) and beclomethasone (50 mu g) metered dose inhalers (MDIs) using an Anderson cascade impactor and ultraviolet spectrophotometry. Five adult-mouthpiece Space-Chambers are tested. For comparison purposes, similar measurements are made with the MDIs alone and with five adult-mouthpiece Aerochamber (Trudell, London, Ontario, Canada) holding chambers. Compared with the MDI alone, the Space-Chamber significantly increases the dose inhaled in fine particles (<4.7-mu m aerodynamic diameter) for beclomethasone by 32% (P < 0.01) and does not alter this dose for salbutamol (P > 0.05). Deposition on the metal impactor intake ''throat'' is significantly reduced by the Space-Chamber for both formulations (P < 0.01) to less than 1% of that depositing with the MDI alone. The Aerochamber did not differ significantly from the Space-Chamber in impactor dose, intake throat dose, or dose in particles less than 4.7 mu m for either formulation. For beclomethasone, however, significant differences between the devices occurred in the inhaled dose in particles less than 3.3 mu m (10.9 mu g for Space-Chamber, 8.2 mu g for Aerochamber, 7.3 mu g for MDI alone). For salbutamol, the devices differed significantly in the inhaled dose in particles less than 2.1 mu m (21.2 mu g for Aerochamber, 19.5 mu g for MDI alone, 16.8 mu g for Space-Chamber).