Microstructural insight into inhalation powder blends through correlative multi-scale X-ray Computed Tomography

Parmesh Gajjar, Ioanna Danai Styliari, Victoria Legh-Land, Hrishikesh Bale, Benjamin Tordoff, Philip Withers, Darragh Murnane

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Dry powder inhalers (DPI) are important for topical drug delivery to the lungs, but characterising the pre-aerosolised powder microstructure is a key initial step in understanding the post-aerosolised blend performance. In this work, we characterise the pre-aerosolised 3D microstructure of an inhalation blend using correlative multi-scale X-ray Computed Tomography (XCT), identifying lactose and drug-rich phases at multiple length scales on the same sample. The drug-rich phase distribution across the sample is shown to be homogeneous on a bulk scale but heterogeneous on a particulate scale, with individual clusters containing different amounts of drug-rich phase, and different parts of a carrier particle coated with different amounts of drug-rich phase. Simple scalings of the drug-rich phase thickness with carrier particle size are used to derive the drug-proportion to carrier particle size relationship. This work opens new doors to micro-structural assessment of inhalation powders that could be invaluable for bioequivalence assessment of dry powder inhalers.

Original languageEnglish
Pages (from-to)265-275
Number of pages11
JournalEuropean Journal of Pharmaceutics and Biopharmaceutics
Early online date30 Aug 2023
Publication statusPublished - 30 Oct 2023


  • Health and Wellbeing
  • Pharmaceutics
  • Inhaled drug delivery
  • X-ray computed Tomography
  • Correlative Tomography
  • Microstructure
  • Powder
  • Correlative tomography
  • Microstructural equivalence
  • Powder characterisation
  • X-ray computed tomography
  • Inhalation


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