Influence of blender type on the performance of ternary dry powder inhaler formulations

Mats Hertel, Eugen Schwarz, Eva Maria Littringer, Mirjam Dogru, Sabine Hauptstein, Hartwig Steckel, Regina Scherließ

The importance of the right blending order and the mixing parameters for ternary mixtures prepared with a high shear mixer was shown in a previous study. This project was applying a Design of Experiment (DoE) to elucidate whether the gained findings are specific for a high shear mixer or if they can also be attributed to a low shear tumble blender. For this purpose, ternary mixtures were prepared with a Turbula® tumble blender and a Picomix® high shear mixer using two different blending orders and the same number of total rotations of the blender. Afterwards, the blends were tested with an inhaler device (Novolizer®) by impaction analysis using the Next Generation Pharmaceutical Impactor (NGI). Fine particle fraction (FPF), fine particle dose (FPD) and mass median aerodynamic diameter (MMAD) were then compared with the factors blender type, blending order and rotations of the blender. Results exhibited that all factors impacted on the FPF and FPD, with the lowest effect arising from the blender type. Blending order findings and SEM pictures proved the saturation of active sites and the function of fines as a buffer during blending. Overall, improved knowledge of the exact mechanism about how fines influence the aerodynamic performance, in particular for the blending process, could be illustrated in this work.

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