DICLOFENAC RELEASE FROM EUDRAGIT-CONTAINING MATRICES AND EFFECTS OF THERMAL-TREATMENT

Ethyl acrylate-methyl methacrylate copolymer (Eudragit NE40D) was eval uated as matrix material for preparing controlled-release tablets of d iclofenac sodium. Drug release could be modified in a predictable mann er by varying the Eudragit NE40D content, but was pH dependent, being markedly reduced at lower pH. This could be attributed to the low solu bility of the drug at these pH values. Thermal treatment of the tablet s at 60 degrees C was also found to affect the rate of drug release, w hich was found to decrease with an increase in the treatment duration, but could be stabilized after 96 hr of treatment. This was also assoc iated with a corresponding increase in the tablet tensile strength. Ho wever, treatment of the granules for 5 hr prior to compaction into tab lets could shorten the stabilizing time of the drug release to 48 hr a nd that of the tensile strength to 24 hr. The effect of thermal treatm ent may be ascribed to better coalescence of the Eudragit particles to form a fine network, resulting in matrix of higher tortuosity and low er porosity.