PREPARATION AND EVALUATION OF SODIUM DICLOFENAC CONTROLLED-RELEASE TABLETS .2. DIBASIC CALCIUM PHOSPHATE AS A RETARDENT IN MIXTURES FOR DIRECT COMPRESSION

The dissolution behaviour of a direct compression compact prepared wit h sodium diclofenac and dibasic calcium phosphate (DCP) in different w eight ratios with or without Biosoluble polymer(R) (acrylic-based resi n) was investigated io distilled water and in a medium with changing p H. The results indicate that the amount of sodium diclofenac released from the compact was dependent on the amount of drug and DCP used in t he compact, and was also controlled by the amount of Biosoluble polyme r(R) added. A chemical reaction forming diclofenac acid might occur on the surface of the sodium diclofenac compact during exposure to the a cidic medium, which was confirmed by diffuse-reflectance spectroscopy. The tablet with a 1:2 weight ratio of sodium diclofenac to DCP exhibi ted a sustained-release behaviour, similar to commercial sustained-rel ease products (Voltaren SR-100(R) and Grofenac Retard(R)), but a lower release rate was found as compared to the commercial products. The di ssolution behaviour of the study table and the commercial products was found to be dependent on the dissolution medium and the rotating spee ds. Class beads were added to the dissolution assembly to simulate the influence of food, and the enhanced friction between tablet and glass beads might result in a higher dissolution rate of the tablet and the commercial products.