Impact of co-solvent concentration on multicomponent metered-dose inhaler formulation properties

Pressurized metered dose inhalers (pMDIs), used for asthma treatment, exhibit poor drug delivery efficiency, influenced by their formulation properties. This study addresses the gap in literature regarding thermodynamic properties of low global warming potential (GWP) propellants such as HFA152a and HFO1234ze(E) in ethanol, revealing non-ideal mixture behaviour. Impact of ethanol on low GWP alternatives was assessed through experiments and thermodynamic modelling, revealing non-ideal behaviour and reduced vapour pressure. The developed property lookup functions using experimental data, based on equation of state, facilitate mass flux calculations, indicating lower activity coefficients and reduced sensitivity of HFA152a to ethanol concentrations compared to HFO1234ze(E).