title: Evaluation of the TSI aerosol impactor 3306/3321 system using a redesigned impactor stage with solution and suspension metered-dose inhalers.
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.
authors.affiliation: College of Pharmacy, University of Arizona, 1703 East Mabel St, 85719, Tucson, AZ. harris@pharmacy.arizona.edu.
authors.forename: Julie A
authors.initials: JA
authors.lastname: Harris
authors.affiliation: Early Pharmaceutics and Technology Laboratory, 3M Drug Delivery Systems, St Paul, MN.
authors.forename: Stephen W
authors.initials: SW
authors.lastname: Stein
authors.affiliation: College of Pharmacy, University of Arizona, 1703 East Mabel St, 85719, Tucson, AZ.
authors.forename: Paul B
authors.initials: PB
authors.lastname: Myrdal
keywords: aerosols; metered-dose inhalers; particle sizer; size distribution