The Packing Coefficient: a Suitable Parameter to Assess the Flow Properties of Powders

Abstract

A parameter, defined by Gabaude et al. in a previous work ¹⁾, was further investigated for its ability to evaluate flow properties of particulate materials. It is based on the volume reduction of the powder bed under low compaction pressure. Compaction data and the packing coefficient (C_t=[(H₀-H_p)/H₀].100) were analysed over a [0-1] MPa pressure range. Comparison of the C_t value with the flowability index (i) determined by Jenike shear cell measurements demonstrated the reliability of this packing coefficient to assess powder flow properties using small quantities of powder (<1g). This method appeared to be helpful for an adequate determination of flowability in the early stages of drug development. Finally, because the packing assessment is performed in a compression die, improvement in the prediction of the weight variation of tablets is expected, as compared with other methods of flowability assessment.