Irene Rossi1 & William J. Ganley1, Philip Chi Lip Kwok2, Ivan Zadrazil3, Graham Hassall3, Olivier Michelet4, Segolene Sarrailh4, Guillaume Brouet4, Robert Price1 & Jagdeep Shur1
1Nanopharm Ltd, An Aptar Pharma Company, Cavendish House Hazell Drive, Newport NP10 8FY
2Sydney Pharmacy School, Faculty of Medicine and Health, University of Sydney, Pharmacy and Bank Building A15, NSW 2006, Australia
3Dantec Dynamics, Garonor Way, Royal Portbury, Bristol, BS20 7XE
4Aptar Pharma, Route des Falaises, 27100, Le Vaudreuil, France
Summary
Lower global warming potential (GWP) propellants (hydrofluoroalkane, HFA, 152a and hydrofluoroolefin, HFO, 1234ze) are readily available replacements to those currently employed in life-saving medications (HFA 134a and 227a). This study aimed to investigate fundamental physical properties of aerosols emitted from pMDIs using currently employed propellants and low GWP alternatives. The net surface charges for all propellants were positive, however HFO 1234ze generated near-neutral charges of both polarities, with HFO being the least bipolar propellant. However, water content was higher for this propellant as result of storage conditions and contribution of sub-assembly components (valve, canister, and actuator). Net charge may determine relevant differences in aerosol deposition and, therefore, should drive formulation development approaches. The droplet diameter and velocity for the different propellants fell into multiple groups (for example: the two low GWP propellant droplets were larger at short distances from the actuator). This information will guide the use of excipients to achieve desirable performance of products reformulated using these propellants. Finally, the results evidenced as well the influence of valve and actuator’s material components on the net-charges developed. Therefore, device sub-assembly components play an important role during pMDI re-formulation and development.
Key Message
The fundamental properties of currently used and new low GWP propellants have been characterised. Differences in aerosol droplet surface charge were observed for HFO 1234ze. Moreover, low GWP propellants droplets were larger at short distances from the actuator. These may determine relevant differences in aerosol deposition, which can be balanced by formulation composition.