Low GWP pMDIs: Evolving a Proven Inhaler Platform for Sustainability
This article explores how the transition to low‑global warming potential propellants is shaping the next evolution of the pMDI platform. It examines why pMDIs remain essential in global respiratory care, how low‑GWP propellants introduce system‑level challenges across formulation, valve design, manufacturing and regulation, and why integrated development and supply readiness are critical as low‑GWP pMDIs move from development to commercialisation—while maintaining patient confidence and continuity of care.
Why pMDIs Still Matter in a Sustainability‑Focused Future
For more than half a century, pressurised metered dose inhalers (pMDIs) have been a cornerstone of global respiratory care, delivering reliable and life‑saving therapies to hundreds of millions of patients worldwide. Their proven performance, affordability, and ease of use have made them indispensable across healthcare systems, particularly in acute and rescue settings where familiarity and confidence are essential. As sustainability commitments increasingly shape healthcare decision‑making, pMDIs remain highly relevant—not despite these pressures, but because of their scale, accessibility, and capacity to evolve without disrupting patient care.
While alternative inhalation technologies continue to emerge, replacing a specific drug delivery platform is not always the most realistic or responsible path forward. For many patient populations, including paediatric and elderly patients or those managing acute exacerbations, continuity of care and device familiarity are critical. From a healthcare system perspective, pMDIs remain among the most cost‑effective and globally scalable inhalation solutions available. As a result, efforts to reduce the environmental footprint of respiratory therapies are increasingly focused on evolving the pMDI platform itself rather than abandoning it.
Low‑GWP Propellants: A System‑Level Evolution, Not a Simple Switch
The transition to low‑global warming potential (low‑GWP) propellants represents the next major chapter in the evolution of pMDIs. Building on earlier transitions driven by the Montreal Protocol, new propellants such as HFA152a and HFO1234ze offer the potential to reduce the carbon footprint of pMDIs by more than 90% compared with current propellants. However, this shift is not a simple substitution exercise. Differences in physicochemical properties—including vapour pressure, density, solvency and flammability—introduce technical considerations that affect the entire pMDI system.
These changes influence formulation stability, aerosol generation, lung deposition, material compatibility, extractables and leachables risk, as well as manufacturing and filling requirements. As a result, low‑GWP propellants act as a catalyst for broader innovation, prompting a reassessment of components and processes originally designed around legacy propellant chemistries. Successfully navigating this transition requires viewing the pMDI as an integrated system rather than a collection of interchangeable parts.
Evolving the Valve to Manage Risk and Preserve Patient Confidence
At the centre of the pMDI system lies the metering valve, which functions as the critical interface between formulation, device and patient. Legacy valve designs were optimised for traditional hydrofluoroalkane propellants, and relying on them unchanged for low‑GWP formulations can increase development risk. Purpose‑built valve design therefore plays a key role in enabling the next generation of pMDIs.
Engineering valves specifically for low‑GWP propellants helps address challenges such as material compatibility, moisture barrier performance and long‑term stability, while also reducing extractables and leachables risk. At the same time, preserving familiar inhaler architecture and delivery characteristics is essential to minimise changes in patient technique, reduce retraining requirements and maintain confidence in dose delivery. By balancing technical redesign with usability continuity, the pMDI platform can evolve without disrupting established treatment routines.
Scaling Sustainably: From Development to Commercial Readiness
As low‑GWP pMDIs move from development toward commercialisation, manufacturing readiness and supply chain resilience become increasingly critical. Low‑GWP propellants introduce new safety considerations, including flammability, which require appropriate facilities, processes and expertise. ATEX‑rated research and development environments, safe filling capabilities and robust quality systems are essential to support a smooth transition from early development to large‑scale manufacturing.
Beyond manufacturing, successful scale‑up depends on an integrated approach that aligns formulation, device development, analytical testing and regulatory strategy. Advanced development tools that combine in vitro testing, in silico modelling and computational fluid dynamics can help anticipate performance changes earlier in development, reducing trial‑and‑error and avoiding late‑stage surprises. Regulatory readiness, supported by comprehensive documentation and alignment with evolving requirements, further de‑risks the path to market.
Taken together, these capabilities enable low‑GWP pMDIs to deliver meaningful environmental progress while safeguarding product performance, patient access and long‑term compliance. Rather than disrupting a trusted delivery platform, the transition to low‑GWP propellants demonstrates how pMDIs can continue to evolve—responding to new sustainability imperatives while preserving the standards of care that patients and healthcare systems depend on. The pMDI platform has evolved before, and with the right system‑level perspective, it is ready to do so again.
