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Advanced Surface Chemistry Characterization to Understand Physical Stability and Performance Of Dry Powder Inhalers

Zhou T, Shetty N, Zhang Y, Zemlyanov D, He A, Ahn P.

Respiratory Drug Delivery 2020. Volume 1, 2020: 91-100.

Abstract:

Spray drying has been increasingly applied to produce inhalable drug particles. However, spray dried particles containing multiple components may have heterogeneous distribution of various components in each particle, particularly on the particle surface. It is important to understand the effect of surface composition on the stability of dry powder inhaler formulations; however, characterization of surface chemistry on such fine inhalable particles is very challenging. We have developed an advanced analytical platform to enable surface chemistry characterization of inhalable particles. Combination particles of azithromycin and colistin were produced by a 3-fluid-nozzle (3N) spray drying to explore the utility approach compared to the conventional 2-fluid-nozzle. In this study, X-ray photoelectron spectroscopy (XPS) data proved the hypothesis that surface enrichment of hydrophobic azithromycin in the 3N co-spray dried particles prevented moisture-induced reduction in aerosol performance. This study shows the importance of surface chemistry characterization for understanding aerosol performance and that control of the surface composition may be used to improve the stability of dry powder inhaler formulations.