PURPOSE: To determine if cascade impactor (CI) measurement of drug in small particles from aqueous nasal sprays, described in FDA's 2003 draft Nasal Bioavailability/Bioequivalence Guidance, can be optimized to reduce measurement variability. To examine the influence of flow rate configurations and number of impactor stages on CI deposition and explore the importance of inlet volume. METHODS: A total of eight assemblies and manual vs. automatic actuation were tested for deposition on the sum of all stages of the CI, and for Group 2 total drug mass per the Guidance. Mean deposition and variance about the mean were determined for each assembly. RESULTS: The path length for a spherical 1 l inlet was too short to allow adequate aerosol formation. Data variance was reduced by a factor of two or more by using an automatic actuator relative to manual actuation. Impactor assembly modification did not improve variance over the standard assembly. CONCLUSIONS: Use of a spherical inlet (≥ 2 l volume) and automatic actuation are recommended for comparative measurements of drug in small particles arising from aqueous nasal sprays. The standard (8-stage) 28.3 lpm CI flow rate configuration is recommended when using the Andersen Cascade Impactor (ACI), as no other assembly showed a distinct advantage.
PURPOSE: To determine if cascade impactor (CI) measurement of drug in small particles from aqueous nasal sprays, described in FDA's 2003 draft Nasal Bioavailability/Bioequivalence Guidance, can be optimized to reduce measurement variability. To examine the influence of flow rate configurations and number of impactor stages on CI deposition and explore the importance of inlet volume. METHODS: A total of eight assemblies and manual vs. automatic actuation were tested for deposition on the sum of all stages of the CI, and for Group 2 total drug mass per the Guidance. Mean deposition and variance about the mean were determined for each assembly. RESULTS: The path length for a spherical 1 l inlet was too short to allow adequate aerosol formation. Data variance was reduced by a factor of two or more by using an automatic actuator relative to manual actuation. Impactor assembly modification did not improve variance over the standard assembly. CONCLUSIONS: Use of a spherical inlet (≥ 2 l volume) and automatic actuation are recommended for comparative measurements of drug in small particles arising from aqueous nasal sprays. The standard (8-stage) 28.3 lpm CI flow rate configuration is recommended when using the Andersen Cascade Impactor (ACI), as no other assembly showed a distinct advantage.
Authors: Dave Christopher; Paul Curry; Bill Doub; Kenneth Furnkranz; Martin Lavery; Karl Lin; Svetlana Lyapustina; Jolyon Mitchell; Brian Rogers; Helen Strickland; Terrence Tougas; Yi Tsong; Bruce Wyka Journal: J Aerosol Med Date: 2003
Authors: Matthew Bonam; David Christopher; David Cipolla; Brent Donovan; David Goodwin; Susan Holmes; Svetlana Lyapustina; Jolyon Mitchell; Steve Nichols; Gunilla Pettersson; Chris Quale; Nagaraja Rao; Dilraj Singh; Terrence Tougas; Mike Van Oort; Bernd Walther; Bruce Wyka Journal: AAPS PharmSciTech Date: 2008-02-28 Impact factor: 3.246