Innovative pMDI formulations of spray-dried nanoparticles for efficient pulmonary drug delivery.

For drug delivery to the lungs, the aerodynamic size of drug particles plays a predominant role in determining the sites of deposition in the airway, and the particles with the size less than 2μm are highly expected as they will be preferably delivered to the ideal site of alveolar regions. In this paper, a novel platform technology has been developed, where the water (containing pharmaceutically active agents)-in-oil (w/o) microemulsions were spray-dried to generate nanosized drug particles that were able to be homogeneously dispersed in the propellant to form an exceptionally stable suspensions with no precipitates or flocculates during a long time storage. High fine particle (<5.8μm) fraction (∼70% w/w) was achieved, irrespectively of drug molecular size and storage time. This platform technology works pretty well on chemical drugs (i.e. salbutamol sulphate) and biotherapeutics (i.e. insulin) for the generation of nanoparticles, and the nanoparticle pMDI formulations were homogeneous, stable and of high delivery efficiency to the lungs, representing an ideal way for pulmonary delivery.