The most extensively used test for predicting in-vivo release kinetics of a drug from its orally administered dosage forms is dissolution testing. For polysaccharide based, colon targeted oral delivery systems, the entire path of the gut traversed by the dosage form needs to be simulated for assessing its in-vivo dissolution pattern. This includes the dissolution testing sequentially in simulated gastric fluid (SGF), simulated intestinal fluid (SIF) and simulated colonic fluid (SCF). For SGF and SIF, simple and standardized composition is well-known. However, preparation of SCF requires addition of either the colonic contents of rodents or human faecal slurry. A method is proposed, wherein a mixture of five probiotics cultured in the presence of a prebiotic under anaerobic conditions is able to surrogate the colonic fluid. Release profiles of drug from colon targeted delivery systems in this medium were studied and compared to those generated in the conventionally used media containing rodent caecal contents and human faecal slurry. The results from the three studies were found to be quite similar. These findings suggest that the proposed medium may prove to be useful not only as a biorelevant and discriminatory method but may also help in achieving the 3Rs objective regarding the ethical use of animals.
Keywords: Colonic microbiota; Polysaccharide based colon targeted delivery systems; Probiotics; Rat caecal contents; Simulated colonic fluid.
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