DESIGN AND DEVELOPMENT OF CORE IN-CUP TABLET OF AZATHIOPRINE

Colon targeted drug delivery has gained increasing significance for the delivery of drugs for the treatment of local diseases. To accomplish a successful colonic delivery a drug desires to be protected from absorption in the GI tract and immediately release in to the proximal colon which is considered the optimum site for colon-targeted delivery of drugs. The purpose of this study is to explore the possibility of core in cup tablet as a novel carrier for colonic delivery of a sparingly soluble drug, Azathioprine.The study involves designing a tablet for colon-target which consists of a central blended form of drug and polymer core and were further coated with different concentrations of CAP to thin film and fine thickness and finally the core-in-cup is over coated with pH-sensitive polymer, by spray coat method to provide acid and intestinal resistance. In vitro drug release studies of tablets were carried out in different dissolution media, i.e., 0.1 N HCl (pH 1.2), phosphate buffers pH 6.8 and 7.4, The physicochemical parameters of all the formulations were found to be in compliance with the pharmacopoeial standards. The stability studies of all formulations were performed as per ICH guidelines. The results demonstrated that the tablets coated with cellulose acetate phthalate 5%, 7.5 % and 10% w/w showed a sustained release of 98.60% for 24 h in the colon. Drug release study in simulated pH7.4 phosphate buffer (colonic fluid) revealed the delayed release nature of Eudragit coating. Kinetic data proved that the optimized colon drug delivery system was fitted well into zero-order kinetics, and apparent lag time was found to be 5 hours, followed by peppas release model.

Keywords: Azathioprine, Biodegradable gums, Eudragit, film coat, core in cup tablet