Evaluating a Variable Volume and Flow Resistance Compensator for the Matching of Flow Rate Rise-Time Profiles between Full Resolution and Abbreviated Impactors when Testing Dry Powder Inhalers (DPIs)
Ben Bradley1 & Mark Copley1
1Copley Scientific Ltd, Colwick Quays Business Park, Road No 2, Nottingham, NG4 2JY, UK
Summary
Abbreviated Impactor Measurement (AIM) is a simple, robust alternative to full resolution aerodynamic particle size distribution (APSD) measurement with several perceived benefits for both R&D and QC applications. However, differences between the flow rate rise-time profile of AIM and full resolution impactors are a recognised issue for use in dry powder inhaler (DPI) testing because of the dependence of DPI drug delivery on inspiratory flow rate rise-time. A variable volume and flow resistance compensator (VRC) has been developed to address this issue and used to match the flow rate rise-time profiles of AIM apparatuses with their full resolution counterparts, using a commercial DPI device. Flow resistance and flow rate rise-time were successfully matched for both the Andersen Cascade Impactor (ACI) and Next Generation Impactor (NGI). The results demonstrate the utility of the VRC for laboratories seeking to match flow rate rise-time profiles and apply closely comparable test conditions when using AIM for DPI testing.
Key Message
Using an accessory for volume and flow resistance compensation allows scientists to match flow resistance and flow rate rise-time profiles of AIM with full resolution cascade impactors to ensure comparable conditions for passive DPI device activation and initial powder aerosolisation and, by extension, achieve better parity between test set-ups.