Organic esters of plasticizers affecting the water absorption, adhesive property, glass transition temperature and plasticizer permanence of Eudragit acrylic films

The materials used in film coating technology are very important tools for pharmaceutical applications. The effects of four organic esters used as plasticizers (triacetin, diethyl phthalate (DEP), dibutyl phthalate (DBP) and tributyl citrate (TBC)) on the water absorption behavior and adhesive property of Eudragit films and on the glass transition temperature (T-g) and plasticizer permanence of Eudragit E film were investigated. The results indicate that the water absorption of these Eudragit films was dependent on the type of Eudragit polymers and plasticizers used. Eudragit E film plasticized with triacetin showed a slight water absorption, but when plasticized with DEP DBP or TBC did not. All Eudragit RL films showed significant uptake of water, but Eudragit RS films exhibited a lesser degree of water absorption. The adhesion (tack value) of all Eudragit films was markedly increased when the concentration of plasticizer was greater than 25%. Eudragit E film exhibited a greater adhesiveness than the Eudragit RL or RS film, particularly with higher plasticizer concentration. Weight loss of the Eudragit E film plasticized with triacetin or DEP was more pronounced with aging, but when plasticized with DBP or TBC weight loss was not seen. The results indicate that TBC may be the best choice of plasticizer for Eudragit film, particularly for the Eudragit E film. (C) 2000 Elsevier Science B.V. All rights reserved.