Evaluation of the TSI aerosol impactor 3306/3321 system using a redesigned impactor stage with solution and suspension metered-dose inhalers |
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Authors: | Julie A Harris Stephen W Stein Paul B Myrdal |
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Institution: | (1) College of Pharmacy, University of Arizona, 1703 East Mabel St, 85719 Tucson, AZ;(2) Early Pharmaceutics and Technology Laboratory, 3M Drug Delivery Systems, St Paul, MN |
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Abstract: | The purpose of this research was to evaluate a redesigned impactor stage for the TSI Model 3306 Impactor Inlet with nozzles
adjusted to obtain a target cut-point of 4.7 μm. It has been determined that the previous cut-point used in the Model 3306
was nominally closer to 4.14 μm, thus potentially impacting the characterization of aerosol mass. The reassessment of the
Model 3306 was performed on 4 solution and 2 suspension metered-dose inhaler (MDI) formulations. The redesigned impactor stage
resulted in a 5% to 6% increase in aerosol mass when compared with the previous impactor stage for the products Ventolin-HFA,
Proventil-HFA, and 2 cyclosporin solution formulations with high ethanol concentrations (15% wt/wt). For the formulations
with low ethanol concentrations (3% wt/wt), minimal differences were observed between the 2 cut-points. In addition, this
study reevaluated the requirement of a vertical inlet extension length when using the TSI 3306/3321 system with the redesigned
cut-point. It was shown that the use of a 20-cm extension provides mass and aerosol size distributions that are comparable
to the Andersen 8-stage Cascade Impactor, for both solution and suspension MDIs. This work indicates that the TSI 3306/3321
system is suitable for preformulation studies of both suspension and solution MDI systems.
Published: March 10, 2006 |
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Keywords: | aerosols metered-dose inhalers particle sizer size distribution |
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