Controlled shear system and resonant acoustic mixing
Lubrication is critical in pharmaceutical manufacturing of solid dosage forms. The purpose of this paper is to systematically compare and correlate the lubrication effect of two devices, a
controlled shear system and a Resonant Acoustic Mixer, on the flow properties of pharmaceutical blends.
A model formulation was selected. Full factorial designs were conducted to examine the effect of the total strain (or total energy) and the shear rate (or power) on the powder blend flow
properties. Analysis of variance (ANOVA) and effect size test using omega-squared statistics were performed.
Lubrication significantly improved the blend flowability. Mixing without magnesium stearate, or insufficient strain, resulted in more cohesive blends. The statistical analysis suggests that
the shear rate had a minimal effect on the blend flow properties. The experimental results also suggest that although the two devices had comparable lubrication effects on the overall blend
flowability, the changes of the interparticle forces in the lubricated blends were not identical.
This study demonstrated a scientific approach to compare different lubrication processes in an objective and reproducible manner. The findings are useful for process design, development, and
transfer between different equipment types and process scales.