The objective of this study was to investigate the influence of inulin (IL) and maltodextrin (MD) as matrix formers on the physical properties of drug nanocrystal-embedded microparticles (NEM) during spray-drying and storage. The redispersibility, aerodynamic performance and phase behaviour of NEM/MD and NEM/IL stored at different water activity (aw) values were evaluated. NEM with 2 g/g (relative to the weight of drug) of IL and MD exhibited the excellent performance after spray-drying. The water activity significantly influenced the redispersibility and aerodynamic performance of NEM/MD and NEM/IL. The NEM/MD presented a higher Tg at all aw values than did NEM/IL. The moisture-induced collapse of the amorphous glassy matrix of IL and MD could be responsible for the poor redispersibility and aerodynamic performance of NEM/IL and NEM/MD, respectively. The NEM/MD exhibited better aerodynamic performance at high aw (0.528) than did NEM/IL. Therefore, MD could be an excellent matrix former for inhalable NEM.
Keywords: Aerodynamic performance; Glass transition; Maltodextrin; Nanocrystal-embedded microparticles; Redispersibility.
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