Microbially triggered drug delivery to the colon

Increasing acceptance of protein- and peptide-based drugs necessitates an investigation into the suitability of various sites for their administration. Colon is being investigated for delivery of such molecules. Colon-specific drug delivery is designed to target drug molecules specifically to this area. Development of site-specific delivery systems may exploit a specific property of the target site for drug activation/release. The gastrointestinal tract is inhabited by over 400 bacterial species, each having a specific niche in the tract. Colon, the distal part of the intestine is inhabited by a large variety of gram negative microflora. This flora produces a vast number of enzymes which are being exploited for formulation of colon-specific drug delivery systems. A number of microbially activated systems for colon-specific drug delivery are being evaluated. These include prodrugs and synthetic or natural polymer-based delivery systems. This article aims at reviewing the various microbially activated drug delivery systems for colon-specific drug delivery with specific reference to the microflora of the various segments of the gastrointestinal tract and their role in targeting drug delivery to the colon. (C) 2002 Elsevier Science B.V. All rights reserved.