Release kinetics of sodium diclofenac from a controlled release device

Abstract

Sodium diclofenac (SD) is an ideal candidate for incorporation in a controlled release device due to its short biological half-life and associated adverse effects after oral administration. Many efforts have been made toward achieving sustained- release formulations of SD. The aim of this study was to develop an inexpensive and simple method to produce a microporous membrane-controlled delayed release delivery system via coating a blend of ethyl cellulose (EC) and methyl cellulose (MC) on the surface of tablets, where EC was the film coating agent and MC acted as a leachable pore-forming agent in an aqueous basic medium. The best solvent composition for dissolving both polymers was determined. Coating solutions with differing ratios of polymers were applied and the visual and mechanical properties of the resulting films were investigated. The in vitro release pattern as well as the release kinetics of the designed tablets were also studied. The duration of SD release was found to be directly proportional to the ratio of EC to MC and, thus, coat thickness and pores. All prepared tablets were of good quality with respect to appearance, drug content uniformity, hardness, weight variation, friability, and thickness uniformity. The influence of the coating thickness and the amount of pore forming agent on the drug release rate and release mechanism was investigated. The release data followed different kinetic models according to MC concentration as a pore forming agent. Finally the best formulation with zero order release kinetics was selected, which showed the desired delayed release characteristics and extended release. é ECV.