INFLUENCE OF DIFFERENT-SHAPED PIGMENTS ON BISACODYL RELEASE FROM EUDRAGIT-L-30-D

Self-prepared bisacodyl pellets were coated in a miniature fluid-bed p an 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-shap ed pearl luster pigments with titanium dioxide or iron oxide surfaces, respectively. The pigment volume concentration within all coatings wa s the same. Dissolution tests in artificial gastric fluid showed that platelet-shaped pigments or fillers, independent of their chemical con stitution and polarity of their surfaces, reduce drug release from Eud ragit L 30 D. Coarse platelets have a greater effect than finer ones. Coatings with spherical titanium dioxide and red iron oxide needles ha ve no barrier effect or even lead to an increase in permeability depen ding on their concentration within the coating. Drug release from film s plasticized with DBP was slower than from films with TEC. DBP theref ore is more suitable for Eudragit L 30 D than TEC.