The purpose of this research was to develop and evaluate different sustained release preparations, using swellable polymers as carriers in the form of matrices and three-layer tablets. These preparations may offer a number of therapeutic advantages over immediate release dosage forms in drug delivery. The materials used for the fabrication of these systems were hydrophilic swellable polymers namely Metolose, Polyox, Xanthan gum and an erodible material Gantrez, acting as drug(diclofenac sodium) carriers. The powder characteristics determined for these polymers suggest good flowability with the exception of Gantrez. The addition of 1% of magnesium stearate resulted in improved flow properties for all polymers including Gantrez. Tablets were prepared by direct compression whereas three-layer tablets were prepared by compressing polymer barrier layers on both sides of the core containing the drug. Our findings show that both preparations exhibit sustained release characteristics; also the structure of the device considerably affects the drug release and the release rate. Furthermore erosion and swelling greatly influence the overall behavior, function and performance of the systems. Finally kinetic analysis studies indicated that the drug release mechanisms were also affected by these effects.
Keywords: Sustained release, swelling, erosion, matrix, three layer tablets
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