Eudragit (R): a technology evaluation

Introduction: Eudragit is the brand name for a diverse range of polymethacrylate-based copolymers. It includes anionic, cationic, and neutral copolymers based on methacrylic acid and methacrylic/acrylic esters or their derivatives. Areas covered: In this review, the physicochemical characteristics and applications of different grades of Eudragit in colon-specific/enteric-coated/sustained release drug delivery and taste masking have been addressed. Expert opinion: Eudragits are amorphous polymers having glass transition temperatures between 9 to > 150 degrees C. Eudragits are non-biodegradable, non-absorbable, and nontoxic. Anionic Eudragit L dissolves at pH > 6 and is used for enteric coating, while Eudragit S, soluble at pH > 7 is used for colon targeting. Studies in human volunteers have confirmed that pH drops from 7.0 at terminal ileum to 6.0 at ascending colon, and Eudragit S based systems sometimes fail to release the drug. To overcome the shortcoming, combination of Eudragit S and Eudragit L which ensures drug release at pH < 7 has been advocated. Eudragit RL and RS, having quaternary ammonium groups, are water insoluble, but swellable/permeable polymers which are suitable for the sustained release film coating applications. Cationic Eudragit E, insoluble at pH >= 5, can prevent drug release in saliva and finds application in taste masking.