PH‐Sensitive methacrylic acid–methyl methacrylate copolymer Eudragit L100 and dimethylaminoethyl methacrylate, butyl methacrylate, and methyl methacrylate tri‐copolymer Eudragit E100

Abstract

Poly (methyl methacrylate) derivatives such as Eudragit are largely used for drug encapsulation and in controlled oral drug delivery. With special focusing on those applications, solubilization and precipitation conditions of two pH‐sensitive Eudragit polymers, namely, L100 and E100, were investigated via systematic studies. Effects of various physicochemical parameters such as pH, polymer concentration, salinity, buffer concentration, and incubation time on the solubilization and precipitation of these polymers were investigated. In addition, pH titration of both polymers was reported. Considering both macroscopic and quantitative aspects such as the final mean particle size, size distribution, morphology, and the zeta potential, it was established that the different precited parameters could not be dissociated and exert a synergic action on the solubilization and precipitation of both polymers. Titration curves revealed two equivalences that helped estimating carboxylic content of Eudragit L100 (6 mmol/g) and ammonium content of Eudragit E100 (4 mmol/g). In this study, the solubilization and the precipitation domains were for the first time clearly established by considering the above‐mentioned parameters. Moreover, it was found that Eudragit L100 and E100 cannot be considered as classic polyelectrolytes; in fact, solubilization and precipitation domains were not affected by ionic strength.