In this study, Raman Chemical Imaging (RCI) was used to investigate the active pharmaceutical ingredients (API) particle size distribution (PSD) and degree of drug particle aggregation in a commercial MDI, Flixotide, which contains an anti-inflammatory corticosteroid (fluticasone propionate). Assessment of free-standing API particles and aggregated API particles was done by visual inspection of Raman-identified API particles as it relates to the spatial location of all detected fluticasone particles on a the brightfield and Raman Chemical fusion Images.
By using RCI it is possible also to identify presence of foreign particulates in the formulations and obtain spectrally and spatially resolved images of each particle for accurate particle size determination and recognition of aggregated versus stand-alone particles. RCI can easily separate different chemical species or polymorphic/hydrate forms of the same chemical within single particle or aggregate for identification of polymorphic impurity/unwanted phase transition of the drug.