Multifractal Characterization of Pharmaceutical Hot-Melt Extrudates

Abstract

PURPOSE: Multifractal geometry has become a powerful tool to describe complex structures in many fields. Our first aim was to combine imaging and multifractal analysis to better understand the microstructure of pharmaceutical extrudates. A second objective was to study erosion/dispersion behavior of the formulations because it would condition release of any drug. METHODS: Different formulations containing a lipid, a polymer and different silica based inorganic carriers were produced by hot-melt extrusion at various screw speeds. Multifractal analysis was based on scanning electron microscopy/energy dispersive X-Ray spectroscopy images. This microstructural analysis was complemented with dynamic optical imaging of formulation erosion/dispersion behavior. RESULTS: Multifractal analysis indicated that inorganic carrier type and concentration as well as the screw speed affected the microstructure of the extrudates. The aqueous erosion/dispersion study showed that only the type and concentration of inorganic carrier were important. CONCLUSIONS: The use of microstructural and dispersion analysis appeared to be complementary to better characterize and understand complex formulations obtained by hot-melt extrusion.