High-Speed Laser Image Analysis of Plume Angles for Pressurized Metered Dose Inhalers: The Effect of Nozzle Geometry

Purpose: To investigate aerosol plume geometries of pressurised metered dose inhalers  (pMDIs) using a high-speed laser image system with different actuator nozzle materials and designs.

Method: Actuators made from aluminium, PET and PTFE were manufactured with four different nozzle designs: cone, flat, curved cone and curved flat. Plume angles and spans generated using the designed actuator nozzles with four solution-based pMDI formulations were imaged using Oxford Lasers EnVision system and analysed using EnVision Patternate software. 

Result: Reduced plume angles for all actuator materials and nozzle designs were observed with pMDIs formulations containing drug with high co-solvent concentration (ethanol) due to the reduced vapor pressure. Significantly higher plume angles were observed with the PTFE flat nozzle across all formulations, which could be a result of the nozzle geometry and material’s hydrophobicity. 

Conclusion: The plume geometry of pMDI aerosols can be influenced by the vapor pressure of the formulation, nozzle geometries and actuator material physiochemical properties.