Influence of different-shaped pigments on bisacodyl release from Eudragit L 30 D

Abstract

Self-prepared bisacodyl pellets were coated in a miniature fluid-bed pan coater with Eudragit L 30 D plasticized with dibutyl phthalate (DBP) or triethyl citrate (TEC) and containing different types of pigments, e.g., titanium dioxide, red iron oxide, talc, mica and platelet-shaped pearl luster pigments with titanium dioxide or iron oxide surfaces, respectively. The pigment volume concentration within all coatings was the same. Dissolution tests in artificial gastric fluid showed that platelet-shaped pigments or fillers, independent of their chemical constitution and polarity of their surfaces, reduce drug release from Eudragit L 30 D. Coarse platelets have a greater effect than finer ones. Coatings with spherical titanium dioxide and red iron oxide needles have no barrier effect or even lead to an increase in permeability depending on their concentration within the coating. Drug release from films plasticized with DBP was slower than from films with TEC. DBP therefore is more suitable for Eudragit L 30 D than TEC.