Flow Excursion and Mixing in the Kneading Block Section of Hot-Melt Extrusion Induced by Carrier Density Variation

Abstract With the increasingly widespread use of poorly soluble active pharmaceutical ingredients (API), hot melt extrusion (HME) technology develop rapidly in the pharmaceutical industry as a highly efficient method for preparing solid dispersions of insoluble drugs. Currently, the selection of carrier materials in pharmaceutical production largely relies on experimental trial-and-error, and the influence of specific material parameters—such as carrier density—on the mixing process remains unclear. By employing Computational Fluid Dynamics (CFD) simulations of fluid flow under simplified ideal conditions, this study analyzes the effects of variations in carrier materials on the flow and mixing processes within the kneading block zone of a hot-melt extruder. When the API and carrier fluids are subjected to compression, relative movement occurs between them, resulting in flow excursion. The disparity in carrier density and the shear force variation across the kneading block zone amplifies this excursion, thereby influencing mixing efficiency.