Current cascade impactor protocols do not completely rule out nasal preparations entering the lower respiratory tract. A modified cascade impactor (MCI) was developed to characterize the particle size fraction capable of deposition in the lower respiratory tract. This is an important measure of the potential for delivery to a site which is not the route of administration, and which could lead to potential toxicity. Monodisperse aerosols were utilized to calibrate the Stage -2 and Stage -0 of an Andersen Mk II nonviable cascade impactor at 15 L per minute flow rate. While these sampling conditions are beyond the normal working range of impactor theory in practice the instrument was shown to discriminate the designated particle sizes sampled. This novel setup extended the upper limit of the range of particle sizes that the cascade impactor can characterize from 8.7 to 16.5 mu m. (C) 2007 Wiley-Liss, Inc. and the American Pharmacists Association
