PARTICLE-SIZE MEASUREMENTS FOR THE SPACE-CHAMBER METERED-DOSE INHALERHOLDING 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, Melbou rne, Australia), is characterized for salbutamol (100 mu g) and beclom ethasone (50 mu g) metered dose inhalers (MDIs) using an Anderson casc ade impactor and ultraviolet spectrophotometry. Five adult-mouthpiece Space-Chambers are tested. For comparison purposes, similar measuremen ts are made with the MDIs alone and with five adult-mouthpiece Aerocha mber (Trudell, London, Ontario, Canada) holding chambers. Compared wit h the MDI alone, the Space-Chamber significantly increases the dose in haled in fine particles (<4.7-mu m aerodynamic diameter) for beclometh asone by 32% (P < 0.01) and does not alter this dose for salbutamol (P > 0.05). Deposition on the metal impactor intake ''throat'' is signif icantly 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 eithe r formulation. For beclomethasone, however, significant differences be tween 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 m u 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 Ae rochamber, 19.5 mu g for MDI alone, 16.8 mu g for Space-Chamber).