Effect of Eudragit Resins and Dibasic Calcium Phosphate on the Compation and Dissolution Behavior of Directly Compressible Controlled-Relase Theophylline Tablet

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Abstract
The compaction behavior and release property of tablets made by the combined formulations of Eudragit RLPM and RSPM with or without diabasic calcium phosphate anhydrous (DCPA) using direct compaction were examined. The larger the amount of Eudragit RSPM or DCPA the higher the value of the tensile strenght. A linear realationship was found in the lorgrithm of tensile strength plotted against the porosity of the compacts. The Heckel plot was also used ot evalute the compaction behaviour of tablets. The results indicate that Eudargit RSPM and DCPA are responsible for the good compressiblity of compacts. The contact angle of tablets without DCPA became samller with an increase in the Eudragit RSPM, but exhibited a higher contact angle than tablests with DCPA. The controlled release behavior of theophylline from tablets without DCPA was found and showed a pH-independent property, whereas tablets with DCPA were pH-dependent and exhibited a faster dissolution than tablests without DCPA. The result suggests that controlled-relase and better compressible tablets can be prepared by adjusting the combinatin ratios of Eudragit RLPM and RSPM with or without DCPA by direct compression.