Evaluating the Impact of a Volume and Flow Resistance Compensator on Flow Rate Rise-Time Profiles in Dose Uniformity Testing and Aerodynamic Particle Size Distribution Measurement Apparatus for a Dry Powder Inhaler
Ben Bradley1, Clair Brooks1 & Mark Copley1
1Copley Scientific Ltd, Colwick Quays Business Park, Road No 2, Nottingham, NG4 2JY, UK
Summary
Differences in the internal volume of dose uniformity sampling apparatus (DUSA) relative to the cascade impactor set-ups used for aerodynamic particle size distribution (APSD) measurement are potentially problematic in dry powder inhaler (DPI) testing due to the influence of inspiratory flow rate rise-time on measured characteristics. A variable volume and flow resistance compensator (VRC) enables the matching of flow rate rise-time profiles to address this issue, thereby helping to ensure mass balance in compendial APSD measurement methods. Flow rate rise-time with a DPI DUSA was successfully matched to both the Andersen Cascade Impactor (ACI) and Next Generation Impactor (NGI) to illustrate this approach. The results demonstrate the utility of a VRC for laboratories seeking to minimize sources of variability in DPI testing.