Last reviewed 2026-04-23 · How we verify

HFO-1234ze(E)

HFO-1234ze(E) is a hydrofluoroolefin (HFO) propellant used in metered-dose inhalers as a replacement for chlorofluorocarbon (CFC) and hydrochlorofluoroalkane (HCFA) propellants.

HFO-1234ze(E) is a hydrofluoroolefin (HFO) propellant used in metered-dose inhalers as a replacement for chlorofluorocarbon (CFC) and hydrochlorofluoroalkane (HCFA) propellants. Used for Propellant for metered-dose inhaler formulations in respiratory diseases (asthma, COPD, and other inhaled therapies).

At a glance

Mechanism of action

HFO-1234ze(E) serves as an environmentally friendly propellant in inhaled pharmaceutical formulations, enabling aerosolization and delivery of active pharmaceutical ingredients to the lungs. It has a very low global warming potential (GWP) and zero ozone depletion potential (ODP), making it a sustainable alternative to older propellant technologies. The compound itself is pharmacologically inert and functions purely as a delivery mechanism.

Approved indications

• Propellant for metered-dose inhaler formulations in respiratory diseases (asthma, COPD, and other inhaled therapies)

Common side effects

No common side effects on file.

Key clinical trials

• Study to Assess Effect of Next-Generation Propellant MDI on Mucociliary Clearance Vs. HFA Propellant MDI in Healthy Participants (PHASE3)

Primary sources

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