Artificial dispersing aids and carriers for DPI formulations – Proof of Principle

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Summary

Fundamental influences of shape, size, mass and surface energy involved in the process of cohesion and adhesion of API particles and, for delivery of interactive powder blends, the detachment from the DPI carrier during the inhalation manoeuvre can be investigated by the use of Additive Manufacturing techniques. With these technologies, uniform carrier particles and auxiliary implements of different geometries, sizes and materials can be produced. In this Proof of Principle, several different prototypes were printed using Fused Deposition Modelling (FDM) to obtain uniform structures that can be used as levitating dispersing aids (DA) in DPI formulations. Subsequently, aerodynamic assessments with the NGI were carried out to determine the general influence of different DA design approaches and their respective ability to increase the fine particle fraction (FPF) caused by enhanced dispersion. Results showed that the use of relatively large dispersing aids potentially lead to a slight shift of the MMAD. The magnitude of the shift suggests that dispersion is increased. The geometry of the DA and its respective size, and thus the ratio of volume to surface area, influences the dispersive behaviour inside the inhaler. Fundamentally new applications could be derived in the future with this approach. When the technical limitations are overcome, it should also be possible to print carrier particles with uniform morphology on a µm scale.

Key Message

3D-printed dispersing aids of various geometries and sizes affected the FPF (< 5 µm) of interactive mixtures in DPI formulations. Additively manufactured particles added as auxiliary implements or carrier particles may fundamentally lead to a better understanding of the interrelationship between shape, size and dispersion behaviour during the inhalation procedure.