School of Engineering, Macquarie University, NSW 2109, Australia.
School of Aerospace, Mechanical and Mechatronic Engineering, The University of Sydney, NSW 2006, Australia.
Int J Pharm. 2020 Mar 30;578:119079. doi: 10.1016/j.ijpharm.2020.119079. Epub 2020 Jan 24.
The influence of grid generated mixing on the fluidization of pharmaceutical carrier powders is studied in a channel-flow experiment using direct high-speed imaging and particle image velocimetry (PIV). Four different lactose powders with mass median diameters that range between 61 µm and 121 µm are used. The degree of powder mixing in the flow as a function of grid position relative to the powder bed and grid area blockage ratios (ranging from ~25% to ~40%) is studied for a range of flow-rates. The study presents comprehensive mappings of how pharmaceutical powders are fluidised under the influence of mixing, by examining powder bed morphology, powder emptying rate, and the local flow-field surrounding the pocket. The use of a grid results in higher evacuation percentages (void fraction) and a faster evacuation rate but is associated with randomized evacuation behaviour as observed from the powder bed morphology. Use of a grid can enable evacuation of powder at lower overall flow-rates, which may have important implications on respiratory drug delivery. PIV results show the trend of mean velocities with the mass median powder diameter and demonstrates how a grid with lower blockage ratio can increase the degree of mixing of the evacuating powder and make the evacuation process more rapid. This study contributes towards a better understanding of fluidization processes as relevant to dry powder inhaler devices and sheds light on how simple design alterations, such as adding an upstream grid, can be incorporated to optimise device effectiveness.
网格生成的混合对药物载体粉末流化的影响在通道流实验中使用直接高速成像和粒子图像测速 (PIV) 进行了研究。使用了四种不同的乳糖粉末，其质量中值直径在 61 µm 到 121 µm 之间。研究了网格相对于粉末床的位置和网格面积阻塞比（范围为25%至40%）对不同流速下的粉末混合程度的影响。该研究通过检查粉末床形态、粉末排空率和口袋周围的局部流场，全面研究了混合影响下药物粉末的流化情况。网格的使用导致更高的排空百分比（空隙率）和更快的排空速率，但与从粉末床形态观察到的随机排空行为有关。网格的使用可以在较低的总流速下排空粉末，这可能对呼吸道药物输送有重要意义。PIV 结果显示了平均速度随质量中值粉末直径的趋势，并展示了具有较低阻塞比的网格如何可以增加排空粉末的混合程度并使排空过程更快。本研究有助于更好地理解与干粉吸入器装置相关的流化过程，并阐明如何通过简单的设计改变，例如添加上游网格，来优化装置的有效性。
