The Medicines and Healthcare products Regulatory Agency has approved new versions of Chiesi’s Clenil Modulite asthma inhalers using the lower global warming potential propellant HFA-152a.
Covering the 100 microgram and 200 microgram strengths, the authorisation applies to preventative inhalers containing beclometasone dipropionate for maintenance treatment of adults and children with asthma. UK availability is expected later in 2026, while existing versions will remain on the market during the transition.
The active ingredient, prescribed dose, and clinical indication remain unchanged. HFA-152a replaces the gas used to expel and aerosolise the medicine from the pressurised metered-dose inhaler, preserving the familiar device format while reducing the climate impact associated with established propellants.
Described by the MHRA as the world’s first authorisation of a pressurised metered-dose inhaler using HFA-152a, the decision was granted as a variation to Chiesi Limited’s existing marketing approval. The submission included evidence covering pharmaceutical quality, safety, device performance, and comparability with the established product.
Changing a propellant alters more than the environmental profile of the inhaler. Internal pressure, spray formation, droplet evaporation, particle size, valve performance, seal compatibility, moisture behaviour, and long-term product stability can all change, requiring the complete formulation and device to be reassessed.
HFA-152a is also flammable, which introduces different manufacturing controls from those used with established non-flammable propellants. Filling operations may require dedicated buildings or production areas with suitable ventilation, gas detection, ignition control, hazardous-area electrical equipment, storage arrangements, operating procedures, and trained personnel.
A manufacturer cannot therefore convert an existing line through a simple material substitution. Filling heads, vessels, pumps, pipework, valves, environmental systems, instrumentation, and in-process controls must be assessed or replaced before the complete installation can be qualified for routine manufacture.
A pharmaceutical and mechanical transition
Pressurised metered-dose inhalers combine a medicinal formulation with a precision delivery system, and the canister, metering valve, seals, actuator, propellant, and active ingredient must produce a controlled dose throughout the product’s shelf life. Small changes can affect how much medicine leaves the device and how deeply the resulting particles travel into the respiratory system.
Development programmes consequently include stability studies, dose-uniformity testing, spray characterisation, extractables and leachables assessment, material-compatibility work, pressure testing, and examination of performance as the canister empties. The product must also tolerate storage, transport, temperature changes, repeated handling, and patient use without falling outside the approved specification.
Component suppliers face their own qualification work. Valves, elastomers, canisters, coatings, actuators, and packaging established with one formulation cannot automatically be assumed to perform identically with another, particularly when different pressure or chemical conditions act on contact materials for several years.
Production equipment must meter the formulation and propellant accurately while controlling contamination, leakage, and product variation. Filling speed cannot compromise dose consistency or seal integrity, and detection systems must identify defective canisters before they progress into packaging and distribution.
Validation has to show that the line remains controlled during routine production as well as start-up, shutdown, maintenance, changeover, and minor process variation. Approved operating ranges must be supported by evidence rather than adjusted through informal production experience once commercial batches have begun.
Parallel manufacture presents another challenge, since established and HFA-152a products may remain in production together while further strengths and medicines progress through regulatory review. Companies must prevent material mix-ups, maintain separate safety controls where necessary, and preserve sufficient existing capacity to avoid interruptions in patient supply.
The capital required for dedicated filling and safety infrastructure favours coordinated conversion across product families. A manufacturer needs enough approved volume to justify new buildings, equipment, and operating teams, although waiting for every product to complete assessment could slow the environmental benefits and create a more abrupt later transition.
Dry-powder and soft-mist inhalers already provide alternatives that do not use a propellant, but they are not interchangeable for every medicine or patient. Some users cannot generate the inhalation flow required by particular dry-powder devices, while changes in technique can reduce treatment effectiveness when a device switch is not supported properly.
Lower-impact pressurised inhalers preserve an established delivery route for patients who need it. Maintaining the same medicine and dosage may also reduce the clinical disruption associated with changing device type, although healthcare professionals will still need clear information on appearance, use, availability, and disposal.
The wider transition will place pressure on specialist manufacturing capacity as other inhaler products adopt lower global warming potential propellants. Filling equipment suppliers, component manufacturers, analytical laboratories, safety consultants, and regulatory teams will need to support several conversions without weakening existing supply.
Quality assurance must follow changes made after approval as well as the initial launch. New suppliers, altered production equipment, higher line speeds, and additional manufacturing sites can each affect the validated state of the product, requiring controlled change management and, in some cases, further regulatory submissions.
Chiesi’s authorisation establishes the first commercial reference for HFA-152a within a pressurised medicinal inhaler. The next stage will be governed by factory conversion, component availability, additional product approvals, and the ability to increase output without disrupting a medicine category used in very large volumes.
