SEM-image textural features and drug release behavior of Eudragit-based matrix pellets

Abstract

Matrix pellets of acetaminophen were prepared by extrusion-spheronization using a high proportion of several varieties of Eudragit; namely, 40% RSPO or RLPO, and 17% RS30D or RL30D. The pellets were characterized using textural analysis of gray-level scanning electron microscopy (SEM) images and through the cumulative pore volume distribution obtained by mercury intrusion porosimetry. Surface roughness and distribution of pores at pellet surface were characterized in terms of gray-level non uniformity (GLN) and fractal dimension of pellet surface. Both parameters were strongly dependent on the procedure followed to incorporate the polymer (in powder form or as liquid dispersion) and, to a lesser extent, on the polymer variety (RL or RS). The curing of pellets at 105 °C for 30 min led to the smoothing out and to a decrease in the pore size at the surface, which notably slowed down acetaminophen release rate. Strong correlations between the drug release rate and the surface roughness of the pellets were found.