Change is in the air – the new pressurized metered-dose inhaler propellants

John N Pritchard1

1Inspiring Strategies, Leicester, LE6 0AF, UK


Climate change is increasingly at the forefront of public and political discussions. The fact that the hydrofluorocarbons (HFCs) currently used as propellants in pressurized metered-dose inhalers (pMDIs) have relatively high global warming potential (GWP) has led to their usage becoming increasingly subject to legislation. Recent acceleration of the overall phase down of HFCs, notably in the European Union and in California, could put the availability of affordable pMDI medication at risk towards the end of this decade. At the same time, it is likely that the cost of bulk HFC-134a and -227 propellants will rise substantially over the next few years as other industrial uses decline, and quota mechanisms further impact on availability. Taken together, this could lead to a shortage of affordable reliever medication, even if new exemptions for medical uses were to be introduced.

Three companies have stated publicly that they are actively developing lower-GWP pMDIs. However, only one is a major supplier of rescue medication, which accounts for more than 60% of all emissions from pMDIs. Whilst targeting first launches in 2025, these timelines are at risk if the health authorities require full clinical development programmes to be completed for a change of the propellant, when there are no other substantial changes in the formulation The pharmaceutical industry needs to respond with lower-GWP alternatives whilst at the same time, regulators need to work with the industry to expedite the approval of such new products if essential patient medication is not to be put at risk in the Western world.

Key Message

The phase-down of hydrofluorocarbon (HFC) use is accelerating, such that the use of HFC-134a and -227ea in inhalers is likely to be impacted. In Europe, this may be as early as 2027. There is an urgent need for pharmaceutical companies to begin reformulation progammes if patient supplies are to remain secure.