Formulation and Evaluation of Coated Lornoxicam Tablets for Colon Delivery

Lornoxicam is a non steroidal anti-inflammatory drug of oxicam class and it has the same side effects of this group when taken orally and has a relatively short plasma half-life (3 to 4 h) which makes it a good candidate for colon targeting. It could avoid the systemic side effects, enhance its low oral bioavailability due to hepatic first pass metabolism and delay drug release to target the colon. Eighteen tablet formulations of lornoxicam were prepared by wet granulation and coated with different polymers (pectin, chitosan, ethyl cellulose, cellulose acetate phthalate, eudragit L-100 and eudragit L-100-55), each at three concentration. The tablets were evaluated for their physical characters, in–vitro dissolution in gradient pH, as well as, mathematical modeling using DDSolver software package. The dissolution data best fitted to first order with Tlag model with Krosmyer Pepas (n) values around unity suggesting erosion mechanism for all tablets except pectin coated ones which showed Fickian diffusion mechanism. Fitting the release data to the different erosion models suggested heterogeneous erosion mechanism. Lornoxicam tablets coated with 6% Eudragit L-100 were successfully delivered to the colon with a relative bioavailability of 531.96% compared to the conventional commercial tablets in rabbits.