Influence of processing on the characteristics of matrix pellets based on microcrystalline waxes and starch derivatives

Abstract Matrix pellets based on microcrystalline waxes and starch derivatives were manufactured in the different types of high shear granulators with a volume ranging from 2–70 1. Ibuprofen and theophylline were used as model drugs with a loading of 60 and 70%, (w/w), respectively. The production process and the formulation of the matrix pellets had to be adapted in function of the high shear granulator used. Processing parameters influenced pellet quality. An increasing mixing time and an increasing mixing speed induced a larger pellet size and a lower porosity. For the ibuprofen pellets the lower porosity correlated well with a decrease in release rate. During production the product temperature had to be controlled within a narrow range. The release kinetics of the wax-starch system was described using the equation M t / M ∞ = kt n . The drug release mechanism from the ibuprofen pellets is a Fickian diffusion process, while the theophylline pellets were characterized by a non-Fickian release mechanism.