Design and Evaluation of Diclofenac Sodium MegaloporousMatrix System Aimed forColonic Drug Delivery: Design of a matrix system for diclofenac delivery

Megaloporous controlled release tablets of diclofenac sodium (DS) were preparedwith two kinds of granules. One of them is the restraining-phase matrix granule(RMG) and it controls the release rate of the drug. The other one is the solublehousing-phase matrix granule (HMG) and controls liquid penetration into thesystem. Carnauba wax and Eudragit L100 polymers were used to constitute therestraining and housing matrix phases, respectively. The prepared tablets wereevaluated for various parameters. In vitrodrug release study was carried out insimulated gastric fluid (pH 1.2) for the first 2 h and in phosphate buffer (pH 7.2)for the next 10 h following USP25 paddle method. Two independent modelmethods, AUC and Lin Ju and Liaw's difference factor (ƒ1) and similarity factor (ƒ2)were used to compare various dissolution profiles. The fabricated megaloporousmatrix tablets released only 3 to 5% of DS in pH 1.2 depending on the proportionof carnauba wax used in the RMG. Increase in polymer content/hardness value ofthe tablet resulted in a significant decrease in AUC0-2h and AUC2-12h values . Thef1and f2analysis also confirms the discrimination between corresponding dissolutionpairs. The dissolution profiles of an ideal matrix formulation containing 15.77%carnauba wax and 6.76% Eudragit L100 was found to be comparable with thereference product (Voveran®SR) and theoretical release profile. The drug releasefrom all fabricated products and reference product followed better Higuchi modelthan the zero order and first order kinetic models. Ritger-Peppas model analysisindicated that the DS release followed non-Fickian transport mechanism. From theabove analysis, it is evident that the release mechanism of DS from matrix tabletis influenced by both hardness and polymer contents. The stability profiles indicatethat the physico-chemical properties of the tablets are not affected on storage at 45°C/75% RH up to 6 months