Colon Targeted Drug Delivery Systems -An Overview

Abstract

In the last two decades colon targeted drug delivery has gained increased importance not just for the deliver drugs for the treatment of various colonic diseases but also for its potential for delivery of proteins and therapeutic peptides. In the past various traditional approaches used for colon targeted delivery like prodrugs, pH, time dependent, and microflora activated systems, have achieved limited success. For successful colon targeted drug delivery, the drug needs to be protected from absorption and/or the environment of the upper gastrointestinal tract and then be abruptly released into the colon. Hence continuous efforts have been made on designing colon targeted drug delivery systems with improved site specificity and versatile drug release kinetics to fulfill different therapeutic needs. In last couple of years few new systems have been developed for colon targeted drug delivery such as pressure dependent systems, CODES technology, microsponges, pectin and galactomannan coating, microbially triggered osmotic systems, lectins and neoglyconjugated etc. which are reported to have better in-vivo site specificity and design rationale than the earlier approaches. This review article gives an overview of various approaches for colonic targeted drug delivery with emphasis on newer systems, their merits and demerits, in vitro/ in-vivo evaluation and market status of such delivery systems.

Colon-Targeted Oral Drug Delivery Systems: Design Trends and Approaches

“…Finally, maintaining the stability of the drug in the colon can be a matter of concern. The non-specific interactions of the drug with the colonic content e.g., dietary residues, intestinal secretions, mucus, or fecal matter can have a negative influence on the stability of the drug (5). In addition, the colonic bacterial enzymes may also degrade the drug, rendering it ineffective.…”

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“…The pH-dependent release systems can be prepared using suitable grade of Eudragit. [12,13] Mucoadhesive microparticles coated with a pH-dependent polymer are proposed to initiate the release of the drug at the putative colonic pH 7-8. Hence, the objective of the present research is to develop and optimize capecitabine microspheres for colon targeting by central composite design using Eudragit S100 as pH sensitive polymer, chitosan as mucoadhesive, and sustain-release polymer.…”

Pharmaceutical use of galactomannans

“…Various traditional approaches used for colon targeted delivery have achieved limited success. 111,112 Examples of such approaches include prodrugs (cleavage of the linkage bond between drug and carrier via reduction, and hydrolysis by enzymes from colon bacteria), pH-dependent systems (combination of polymers with pH-dependent solubility to take advantage of the pH changes along the GI tract), time-dependent systems (the onset of drug release is aligned with positioning the delivery system in the colon by incorporation a time factor which simulates the system transit in the upper gastrointestinal tract), and microflora activated systems (primarily, fermentation of non-starch polysaccharides by colon anaerobic bacteria, incorporating the polysaccharide via film-coating and matrix formation). In the latter case (microflora activated systems), galactomannans can be used to deliver drugs to the colon due their susceptibility to microbial degradation in the large intestine.…”

“…In the last few years, in addition to the few new systems that have been developed for colon targeted drug delivery, pectin and galactomannan coatings have been mentioned, and were reported to have better in vivo site specificity and design rationale than for earlier approaches. 112 The combination of pectin and galactomannan for this type of technology was initially proposed by Lee et al. 116 The isolated polysaccharide cannot be used as a drug carrier for colon-specific delivery, due to its high water solubility and swelling characteristics.…”