Physical-mechanical characterization of Eudragit polymers and their application in extended-release matrix tablets prepared via roller compaction

Abstract

The deformation behavior of Eudragit® RS PO and Eudragit® RL PO was evaluated using Heckel Analysis. The polymers exhibited a speed-sensitive deformation behavior typical of plastic materials. The yield values of the binary mixes of the polymers with microcrystalline cellulose revealed a linear relationship with the weight fractions of individual components, whereas, with dibasic calcium phosphate dihydrate exhibited a slight negative deviations from linearity. The work of compaction and the elastic recovery index values of the binary mixtures were found to be linearly related to the weight fractions of the individual components; thus, confirming ideal mixing behavior of these materials. The tensile strengths of the prepared compacts were found to be a function of their solid fraction and independent of the tableting speeds tested; thus, validating compactibility as a reliable parameter in predicting acceptable tablet properties. The influence of plasticizer level, roll pressure and sintering temperature was investigated on the granule properties, tablet breaking force and theophylline release from tablets. Increase in roll pressure and plasticizer levels resulted in a significant increase in the mean particle size of the granules. Roll pressure and plasticizer level also improved the flowability of the formulations. Tablet breaking force increased with an increase in plasticizer level and the sintering temperature. An increase in roll pressure resulted in either no change or a decrease in breaking force of tablets. Theophylline extended-release was obtained for the tablets containing Eudragit® RS PO as a function of plasticizer level and sintering temperature. Tablets containing either Eudragit® RL PO or a binary mixture of RS PO and RL PO failed to give any extended-release under the conditions tested. The study results identified polymer-type as a critical formulation variable; also outlining the importance of other parameters like plasticizer level, roll pressure and sintering temperatures. The feasibility of near-infrared spectroscopy for analyzing the influence of sintering temperature and plasticizer level on the breaking force of matrix tablets prepared via roller-compaction was evaluated. The tablets were thermally treated at different temperatures (50, 75 and 100°C) for 5 hrs. Tablet breaking force significantly increased with increasing plasticizer levels and with increases in the sintering temperature. The principle component analysis was able to separate the spectra based on variables tested. 6-factor and 5-factor partial least squares (PLS) regression models were developed for tablets containing Eudragit® PO and Eudragit® RS PO respectively and found reliable in predicting the breaking force of the tablets.