Formulation and In Vitro Evaluation of Indomethacin Matrix Tablet with pH Modulated Release Kinetics

Controlled release preparations have been reported to reduce the gastro irritant and ulcerogenic effects of Nonsteroidal Anti inflammatory drugs. In the present study, an attempt was made to develop matrix tablet-based controlled release formulations of Indomethacin, using ethyl cellulose as the rate-controlling polymer. In order to prevent initial release of the drug in the acidic environment of the stomach, Eudragit L 100-55 was incorporated in the matrix in varying amounts. It was found that with increasing the proportion of ethyl cellulose in the matrix, the drug release initial release of the drug in the first 2–3 h followed by enhanced release rate in alkaline medium owing to the high solubility of Eudragit L 100-55 at basic pH which led to creation of a porous matrix. It was concluded that combination of Eudragit L 100-55 with ethyl cellulose in the matrix base can be an effective means of developing a controlled release formulation of Indomethacin with very low initial release followed with controlled release up to 14–16 h.