Optimising Actuator Geometries of Low GWP Propellant HFA-152a Solution Formulations
Ameet Sule1, Sunita Sule1, John Howard1, Nisar Ahmed1, Robert Bootle1
1H&T Presspart Inhalation Product Technology Centre, Whitebirk Industrial Estate, Blackburn BB1 5RF, UK
Summary
Low Global Warming Potential (GWP) propellants are being explored for pressurised metered dose inhalers (pMDIs) to reduce the carbon footprint. The selection of propellant in a metered dose inhaler is a substantial change to the product that will require not only a good deal of consideration with regards to the formulation, but also the device componentry for example actuators.
Actuator geometries are critical parameters which influence the shape and size of the aerosol plume and can significantly affect the aerodynamic drug distribution, thereby affecting the overall efficacy of the product for the patient.
Through spray pattern testing, the plume characteristics are used as a comparative tool against other actuator configurations, including a reference device (RLD) and can help predict in-vitro device performance.
The performance of three different solution formulations, with HFA-152a as the propellant and ethanol as a co-solvent, with different actuator geometries were evaluated by assessing the spray behaviour at two distances1. The results were compared against commercially available products with HFA-134a formulations. Several actuator geometry configurations showed comparable performance to the RLD at one distance (p ≥ 0.05, n=15); however, no configuration tested, showed p ≥ 0.05 at both distances.