title: Chitosan: a potential polymer for colon-specific drug delivery system.
abstract: BACKGROUND
  There is an enormous growth and awareness of the potential applications of natural polymers for colon delivery of therapeutic bioactives. Chitosan (CH), a cationic polysaccharide, has a number of vital applications in the field of colon delivery and has attracted a great deal of attention from formulation scientists, academicians and environmentalists due to its unique properties.
  
  
  METHODS
  CH has been widely explored for the delivery of drugs, peptides, proteins and genes to the colon for different therapeutic applications. Sustained and controlled delivery can be achieved with CH-based formulations like CH-coated tablets, capsules, beads, gels, microparticles and nanoparticles. This review mainly focuses on various aspects of CH-based formulations, particularly development of colon-specific delivery of drug.
  
  
  CONCLUSIONS
  The vital properties of CH make it a versatile excipient, not only for sustained/controlled release applications but also as biodegradable, biocompatible, bioadhesive polymer. The colon is recognized as the preferred absorption site for orally administered protein and peptide drugs. The main problem associated with CH is limited solubility at higher pH due to reduced cationic nature, which also reduces mucoadhesiveness. The application of newer targeting moiety with CH-based formulations for highly site-specific delivery of bioactive has to be evaluated for further improvement of therapeutic index (bioavailability).
authors.affiliation: Pharmaceutics Research Projects Laboratory, Department of Pharmaceutical Sciences , Dr Hari Singh Gour Vishwavidyalaya, Sagar-470 003 (MP), India.
authors.forename: Arvind
authors.initials: A
authors.lastname: Gulbake
authors.forename: Sanjay K
authors.initials: SK
authors.lastname: Jain
mesh_terms: D001682:Biological Availability; D048271:Chitosan / Q000737:chemistry*; D003106:Colon / Q000187:drug effects*; D016503:Drug Delivery Systems; D005765:Gastrointestinal Agents / Q000008:administration & dosage*; D006801:Humans; D007408:Intestinal Absorption / Q000187:drug effects*; D007413:Intestinal Mucosa / Q000187:drug effects*; D012995:Solubility
chemical_list: D005765:Gastrointestinal Agents; D048271:Chitosan