Increasing the fine particle fraction of pressurised metered dose inhaler solutions with novel actuator shapes.

In this paper we demonstrate that the use of multiple orifices can improve the fine particle fraction (FPF) of pressurised metered-dose inhaler solution formulations by up to 75% when compared to a single orifice with an equivalent cross sectional area (p<0.05). While prior work has relied on metal actuator components, improvements in micro injection moulding and micro drilling now make it possible to mass produce novel orifice shapes to achieve similar FPF gains in plastic parts, with orifice diameters less than 0.