Lee Y S, Poynter R, Podczeck F, Newton J M
Department of Pharmaceutics, The School of Pharmacy, University of London, 29/39 Brunswick Square, London WC1N 1AX, UK.
AAPS PharmSciTech. 2000 Jul 21;1(3):E21. doi: 10.1208/pt010321.
The purposes of this investigation were to develop a method to evaluate flow properties of powders from avalanching tests and to detect similarities and relationships between these data and conventional powder flow properties. The API AeroFlow automated flowability analyzer was tested using 6 pharmaceutical excipients. Data were presented as mean time to avalanche (MTA), scatter, and a classification based on the type of motion of the powder bed. Powders were also characterized in terms of particle size, particle shape, loss of weight on drying, Carr's compressibility index, and critical orifice diameter to prevent ratholing. A dual approach, which combines visual observation of the type of motion of the powder bed in the rotating drum with numerical descriptors such as MTA and scatter, was found to be more accurate in the assessment of powder flow than the current practice of using only MTA and scatter values. Statistical analysis established that there are relationships and similarities between the ranking of powder flow properties obtained from the avalanching test and Carr's compressibility index and the critical orifice diameter. An interaction between particle size and shape, both influencing powder flow, when evaluated with these methods was found. The assessment of the flowability of powders on the basis of avalanching tests should include both the determination of numerical descriptors of flow such as MTA and scatter, and a determination of the type of motion of the powder bed in order to increase the sensitivity of the method to small changes in powder flow properties.
本研究的目的是开发一种通过崩塌试验评估粉末流动特性的方法，并检测这些数据与传统粉末流动特性之间的相似性和关系。使用6种药用辅料对API AeroFlow自动流动性分析仪进行了测试。数据以崩塌平均时间（MTA）、离散度以及基于粉末床运动类型的分类形式呈现。还对粉末的粒度、颗粒形状、干燥失重、卡尔压缩性指数以及防止鼠洞现象的临界孔径进行了表征。研究发现，将旋转鼓中粉末床运动类型的视觉观察与MTA和离散度等数值描述符相结合的双重方法，在评估粉末流动方面比仅使用MTA和离散度值的现行做法更为准确。统计分析表明，从崩塌试验获得的粉末流动特性排名与卡尔压缩性指数和临界孔径之间存在关系和相似性。在用这些方法评估时，发现粒度和形状之间存在相互作用，二者均会影响粉末流动。基于崩塌试验评估粉末的流动性时，应既包括对流动数值描述符（如MTA和离散度）的测定，也包括对粉末床运动类型的测定，以提高该方法对粉末流动特性微小变化的敏感度。
