New Perspectives from Real-Time, High-Speed Imaging of Metering Valve Filling
Daly T, Mallett T, Gajjar P, Murnane D.
Respiratory Drug Delivery 2026. Volume 1, 2026: 17-0.
Abstract:
This study presents a novel approach for visualizing and quantifying fluid flow during the refill process within a pressurized metered dose inhaler (pMDI) metering valve. By combining high-speed synchrotron X-ray imaging with a custom-designed housing that minimizes attenuation, previously unresolvable flow behavior within the metering chamber has been captured at high spatial and temporal resolution and subsequently translated into quantitative data to characterize the refill behavior using a bespoke image post-processing algorithm.
Significant differences in refill rate and fill percentage were observed across hydrofluoroalkane (HFA) and hydrofluoroolefin (HFO) propellants, with further variation introduced by addition of ethanol and suspended active pharmaceutical ingredient (API). Based on these characterization successes, this innovative approach provides a framework for experimentally evaluating and optimizing new pMDI systems, to support the industry transition to next generation propellants.
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