Development of a novel tablet-in-capsule formulation of mesalamine for inflammatory bowel disease

Objective: The objective of the present work was to develop a tablet-in-capsule type of multiunit system, which releases the drug in a controlled manner at pre-programmed time intervals. Methods: The system consists of an enteric-coated hydroxypropyl methylcellulose capsule filled with four units of mesalamine minitablets, each of which was further coated with different ratios of Eudragit (R) E100 and Eudragit (R) RS100. Results: In vitro evaluation of tablets coated with Eudragit (R) E100 and Eudragit (R) RS100 at different pH conditions revealed that at lower pH levels (2.0, 3.6 and 5.5 pH), the drug release is mainly governed by the dissolution of Eudragit (R) E100 from the Eudragit (R) E100 and Eudragit (R) RS100 coat. In vitro evaluation of capsules enteric coated with Eudragit (R) L100 and Eudragit (R) S100 revealed that a maximum lag time of 3 h and 4 h was obtained, respectively. In vivo roentgenographic evaluation in rabbits revealed that the developed system remained intact until it reaches the targeted region of the gastrointestinal tract, i.e. ileum and colon, where the tablets were released after the dissolution of the enteric coat Eudragit (R) L100 and Eudragit (R) S100, respectively. Conclusion: The developed system exhibited a promising targeting behavior and hence may be used for the treatment of inflammatory bowel disease.