Factorial design-based development of measlamine microspheres for colonic delivery

For treating colonic diseases, conventional oral drug delivery systems are not effective, as they fail to reach the appropriate site of action. Thus, there is a need to develop effective and safe therapy for the treatment of colonic disorders. The aim of the present study was to design a colon-specific delivery system for an anti-inflammatory drug, mesalamine, with minimal degradation and optimum delivery of the drug with relatively higher local concentration, which may provide more effective therapy for inflammatory bowel disease including Crohn disease and ulcerative colitis. Factorial designs (four factors and two levels) for eudragit S-100 (pH-dependent polymer)-coated, pectin (natural polysaccharides)-based microspheres of mesalamine were constructed and conducted in a fully randomized manner to study all possible combinations. Based on the desirability function formulation, F14 was found to be the best formulation. The overall desirability coefficient of formulation F14 was found to be 0.825. The formulation F14 was subjected to in vitro release studies, and the results were evaluated kinetically and statistically. The microspheres started releasing the drug at the beginning of 7th hour, which corresponds to the arrival time at proximal colon. The cumulative percent drug release for formulation F14 at the end of 16 h was found to be 98%. The release kinetics showed that the release followed the Higuchi model, and the main mechanism of drug release was diffusion. The study presents a new approach for colon-specific drug delivery.