Different Types of Direct Compressible Excipients Affecting the Release Behavior of Theophylline Controlled-release Tablets Containing Eudragit Resins

Theophylline released from direct-compressed tablets containing Eudragit RSPM/RLPM and different types of direct compressible excipients was investigated. The influences of the type of dissolution medium and stirring speed on the release behavior of theophylline were also studied. The results showed that the type of direct compressible excipients, dissolution medium and stirring conditions significantly influenced the dissolution rate. The tablet made by dicalcium phosphate or microcrystalline cellulose exhibited the most controlled-release behavior. Almost all the release kinetics of tablets followed a Fickian-transport model.