European journal of pharmaceutical sciences : official journal of the European Federation for Pharmaceutical Sciences
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For about 15 years the performance of dry powder inhalers (DPIs) has been numerically analysed through CFD (computational fluid dynamics) approaches with the objective of understanding the evolving flow structures and the resulting transport of drug particles. Naturally the main interest is the numerical prediction of the emitted fine particle fraction (FPF) which is able to penetrate the lung airways. Due to the mostly used drug formulations (i.e. carrier-based or agglomerated drug powder) and the complex elementary processes occurring during the transport of such particles through inhalers this is not an easy task. ⋯ Hence, the predicted fine particle fraction was found to be close to 100% for both inhalers. As a conclusion of this study, it has become clear that the wall deposition of fine drug particles is an important mechanism during carrier or agglomerate wall collisions, which are responsible for the low emitted fine particle fraction (FPF) observed experimentally. It is hoped that this article provides requirements and guidelines for the further development of Euler/Lagrange simulations applied to dry powder inhaler devices.