Use of “Smartphone” technology to characterise and aid development of a standardised shake for the in vitro analysis of MDIs

Helen Lucke

The through-valve analysis of suspension based Metered Dose Inhalers (MDIs) is susceptible to differences between operators, resulting in biases and seemingly random variability, especially when undertaking though valve delivered dose testing and Aerodynamic Particle size Distribution (APSD) by Cascade Impaction (CI).  Often, key sources of data variability are device handling factors such as the frequency and intensity of shaking applied to the can during analysis.  The aim of this study was to assess whether accelerometer data captured from a standard domestic smartphone could be applied to develop a standardised shake for use by laboratory personnel in order to reduce this variability.  This is desirable in order to increase confidence in results and to improve the likelihood of success when transferring methods between development laboratories and production sites and outsourcing partners.  5 different shakes were investigated and the total on impactor, throat dose and fine particle dose parameters were compared for differences through the life of the MDI and spread of results to determine the most favourable shake.  A standardised shake was developed using characteristics of frequency and duration of shake determined from accelerometer data collected by a smartphone.  This could be provided to trainees in the form of written instruction and/or video footage.

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