1997 OPEN FORUM Abstracts
PARTICLE-SIZE COMPARISON OF MEDISPACER(R) AND AEROCHAMBER(R) IN THE DELIVERY OF PROVENTIL(R) HFA AND PROVENTIL(R) MDI
Scott A. Foss BS, David T. Sladek CRTT, Rebecca E. English BS, Thayer Medical Corporation, Tucson AZ.; Paul D. McGowen RRT, Columbia El Dorado Hospital and Thayer Medical Corporation, Tucson AZ.
Background: It is probable that by the year 2005 CFC propellants will be phased out of use in MDI canisters, to be replaced in many cases by HFA propellants. Proventil HFA is the first of the metered dose inhalers to have made the changeover, and it is expected that several more CFC-free MDIs will appear in the next few years. The purpose of this laboratory study was to determine whether the particle size distributions of Proventil HFA (without CFCs) and Proventil MDI (with CFCs) are affected by the delivery nozzle. We compared results from two hand-held MDI chambers: the MediSpacer, which has a built-in nozzle, and the AeroChamber, which uses the manufacturer's nozzle. Method: The MDI chamber fed into a USP standard throat model, which led to an Andersen cascade impactor; a vacuum pump kept the flow rate through the system at a constant 28 L/min. After multiple doses were administered, the amount of drug deposited on each plate of the cascade impactor was determined by standard UV spectroscopic techniques. The amounts were then normalized to the total amount collected in the cascade impactor. Five tests were averaged for each device/drug combination. Two-tailed t-tests were performed, and any differences were considered statistically significant if p < 0.05. Results: The graphs show that for both MDI drugs the normalized particle size distributions are similar for both devices.
Proventil HFA: (See original for figure)
Proventil MDI: (See original for figure)
For Proventil HFA, p > 0.05 for all eight plates.
For Proventil MDI, p > 0.05 for all plates except for 1 (p = 0.04), 2 (p = 0.006), and 3 (p = 0.02).
Conclusion: The built-in nozzle in the MediSpacer introduces no preferential selection of particle sizes, relative to the manufacturer's nozzle in the AeroChamber.