Benjamin Thorne
Senior Development Engineer
Transitioning to low global warming (GWP) propellants in pressurised Metered Dose Inhalers (pMDIs) is an urgent industry priority. However, because propellants are integral to formulation behaviour and dose delivery, changing propellant can impact product performance and therapeutic efficacy. As a result, the shift to next-generation propellants presents unique formulation, cost and sustainability challenges. It is therefore vital that drug and device developers have access to tools that inform decision-making and facilitate rapid and cost-effective product development without impacting therapeutic efficacy, patient safety or device supply.
In this study, we present a computationally efficient fluid mechanic tool for predicting key metrics of pMDI performance, including ex-actuator droplet size distribution, evaporation to residual droplets, impaction within the Next Generation Impactor induction port, and fine particle mass. Using Bespak 357 series MDI valves and Bespak 636 series actuators, these metrics have been simulated and experimentally derived for two next-generation low GWP propellants: HFO-1234ze and HFA-152a.
This study provides an architecture for the prediction of aerosolisation performance and uses cutting-edge technology and established industry pMDI testing metrics to help developers stay ahead of changing regulations. Bespak is committed to exploring in silico modelling and simulation can be leveraged to develop innovative and reliable tools for the rapid screening and evaluation of pMDI formulations to enable a seamless transition to low GWP propellants.
The results of this work were showcased by Benjamin Thorne, Bespak Senior Development Engineer, at RDD 2026.
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