Comparative studies of powder flow predictions using milligrams of powder for identifying powder flow issues

Characterising powder flowability can be challenging when sample quantity is insufficient for a conventional shear cell test, especially in the pharmaceutical industry, where the cost of the active pharmaceutical ingredient (API) used is expensive at an early stage in the drug product development. A previous study demonstrated that powder flowability could be predicted based on powder physical properties and cohesiveness using a small quantity of powder samples (50 mg), but it remained an open question regarding the accuracy of the prediction compared to that measured using industry-standard shear cell testers and its potential to substitute the existing testers. In this study, 16 pharmaceutical powders were selected for a detailed comparative study of the predictive model. The flowability of the powders was predicted using a Bond number and given consolidation stresses, σ , coupled with the model, where the Bond number represents powder cohesiveness. Compared to the measurements using a Powder Flow Tester (Brookfield) and an FT4 (Freeman Technology) Powder Rheometer shear cell tester, the results showed a good agreement between the predictions and the measurements (15 g) if the available amount of sample is small.