Fluidization of cohesive pharmaceutical powders is difficult to achieve and typically requires the introduction of external forces. This study investigates the fluidization of the fine inhalation grade of lactose powders (size range from 0.1-20 μm) that are specifically developed for dry powder inhalation (DPI) applications. The fluidization behaviour of fine lactose powders was evaluated under six conditions: without fluidization aids, with only vertical vibration (VFA), with only a downward-pointing micro-jet (MFA), with both vibration and pre-mixing with coarse particles (VCFA), with both vibration and micro-jet (VMFA), and with the combined assistance of vibration, micro-jet, and addition of coarse particles (VMCFA). The enhancement of fluidization due to the use of different assistance methods is reflected by the increase of bed expansion and the decrease in both the minimum fluidization velocity and agglomerate formation. However, applying micro-jet results in considerable powder losses due to the high fraction of fine particles stuck to the wall. Combining any two assisting methods leads to better fluidization than using a single approach. In particular, the combination of vibration and micro-jet shows the best performance in improving fluidization. Further addition of coarse particles does not play a significant influence on promoting fluidization. Finally, the analysis of the forces acting on the lactose agglomerates shows the enhancement of separation forces by introducing the fluidization assistance, which leads to a decrease in agglomerate size.

中文翻译：

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干粉吸入用细乳糖的流化：辅助方法的比较

粘性药物粉末的流化很难实现，通常需要引入外力。本研究调查了专为干粉吸入 (DPI) 应用开发的精细吸入级乳糖粉（尺寸范围为 0.1-20 μm）的流化情况。在六种条件下评估细乳糖粉末的流化行为：没有流化助剂、只有垂直振动 (VFA)、只有向下微射流 (MFA)、振动和与粗颗粒预混合 (VCFA) )、振动和微射流 (VMFA)，以及振动、微射流和添加粗颗粒 (VMCFA) 的组合辅助。由于采用不同的辅助方法，流化程度的提高表现为床层膨胀的增加和最小流化速度和结块形成的降低。然而，由于粘附在壁上的细颗粒比例很高，应用微射流会导致相当大的粉末损失。与使用单一方法相比，结合任何两种辅助方法可实现更好的流化。尤其是振动和微射流的结合在改善流化方面表现最好。进一步添加粗颗粒对促进流化没有显着影响。最后，对作用在乳糖团聚体上的力的分析表明，通过引入流化辅助，分离力增强，导致团聚体尺寸减小。