Locally made chitosan covalently linked to indomethacin : a novel approach to formulate sustained release indomethacin capsule in Basrah

The sustained release capsules are pharmaceutical dosage form used for the treatment of chronic rather than acute diseases and are useful because of its convenience and less side effects. This work describes an attempt to formulate indomethacin sustained release capsule using indomethacin covalently linked to chitosan. Chitosan was prepared by alkaline-N-deacetylation of chitin, which was isolated from the shells of local shrimps. The yield of chitosan was found to be 80%. This polymer was found to be white crystal, odorless and the IR spectroscopy of it was similar to a standard reference. Chitosan has been covalently linked to indomethacin and the ratio of drug to polymer was found to be 5 : 1. The chemical interaction between the drug and the polymer was proved by IR studies. In vitro release at different pH were performed and the release of indomethacin in the prepared sustained release capsule were tested and compared with conventional indomethacin capsule INDOMIN-25mg, and a commercial sustained release capsule INDO-75-SR. The release of indomethacin in our product was completed within 12 hours, while the conventional INDOMIN capsule and commercial INDO-75-SR capsule released within 2.5 and 5 hours respectively. In conclusion a cheap, locally made chitosan can be used in formulation of sustained release capsules by covalently linked to drugs containing carboxyl group (like indomethacin) or can be modified to have a carboxyl group.