A shear cell study on oral and inhalation grade lactose powders

TL;DR

This study uses shear cell testing to evaluate the flowability of various lactose powders, aiming to validate the technique, relate flowability to particle morphology, and develop predictive models for powder behavior.

Contribution

It provides a comprehensive assessment of shear cell testing for lactose powders and proposes a mathematical relationship linking particle properties to flow behavior.

Findings

Shear cell testing reliably classifies powder flowability.

Flowability correlates with particle size and shape.

A predictive model for yield locus shape was developed.

Abstract

Shear cell tests have been conducted on twenty different lactose powders, most of which commercially available for oral or inhalation purposes, spanning a wide range of particle sizes, particle morphologies, production processes. The aims of the investigation were: i) to verify the reliability of the technique in evaluating and classifying the flowability of powders; ii) to understand the connection between the flowability of a powder and the morphological properties of its particles; iii) to find a general mathematical relationship able to predict the yield locus shape given the particle size, shape and consolidation state of a lactose powder. These aspects and their limitations are detailed in the manuscript together with other interesting findings on the stick-slip behavior observed in most of the lactose powders examined.