[Effect of EUDRAGIT® RS on the release behaviour of theophylline solid dispersions]

The purpose of this study was to extend the release of theophylline using Eudragit® RS 100 and Eudragit® RSPO as carriers. Solid dispersions of theophylline were prepared by the solvent evaporation technique using Eudragit® RS 100, Eudragit® RSPO and their blend in various drug : polymer ratios. The prepared solid dispersions were characterized with respect to entrapment efficiency, solubility and recovery yield. In vitro drug release of theophylline from the solid dispersions was evaluated in simulated gastric fluid (SGF) and simulated intestinal fluid (SIF) without enzymes. Solubility studies demonstrated a decrease in the solubility of the drug from the solid dispersions. The solubilities of pure drug and solid dispersions were lowered in SGF compared to SIF. Solid dispersions prepared with Eudragit® RS 100 entrapped a greater amount of theophylline in comparison to those with Eudragit® RSPO or the polymer blends and were able to extend the release of theophylline over 24 hrs. Formulation SD4 released 95.52% of the drug in SIF and 93.56% in SGF. Hence, it was selected as the optimized formulation because it was able to extend the release of theophylline over 24 hrs.Key words: solid dispersion extended release Eudragit® drug release.