title: Colon-specific drug delivery using ethylcellulose and chitosan in the coat of compression-coated tablets.
abstract: BACKGROUND
  This study investigates a new means to achieve colon-specific drug delivery.
  
  
  OBJECTIVE
  This study assesses the use of chitosan and ethylcellulose in the coat of a compression-coated tablet to achieve colon-specific drug delivery. The effects of chitosan type and its level as well as the coat thickness were evaluated.
  
  
  METHODS
  Caffeine-containing core tablets were prepared by direct compression. Three chitosan samples with different molecular weight and degree of deacetylation were used. Direct compression produced the finished coated tablet. The product was tested for its potential in colon-specific drug delivery by conducting release studies in simulated gastric and intestinal fluids. Enzymes harvested from rat cecal and colonic contents contributed to a medium to study drug release under colonic conditions.
  
  
  RESULTS
  Essentially no drug was released until action on the tablet by either the acidic pH or the presence of enzymes in the release medium. Chitosan type had no effect on drug release as long as the coating level was the same. Lowering the chitosan level in the coat or increasing the coat thickness increased the lag time.
  
  
  CONCLUSIONS
  The type of chitosan can be changed and yet the product is still susceptible to enzyme or pH effects. This indicates that chitosan present in the coat is still available for such action by the release medium. One can control the chitosan level or the thickness of the coat to achieve a desired delivery profile.
  
  
  CONCLUSIONS
  As colonic media can dramatically promote drug release, the potential for colon-specific drug delivery is confirmed.
authors.affiliation: Philadelphia College of Pharmacy, University of the Sciences, Philadelphia, PA 19104, USA.
authors.forename: Wycliffe
authors.initials: W
authors.lastname: Omwancha
authors.forename: Chahinaz
authors.initials: C
authors.lastname: Kouba
authors.forename: Satish
authors.initials: S
authors.lastname: Yelamanchili
authors.forename: Steven H
authors.initials: SH
authors.lastname: Neau
mesh_terms: D000285:Administration, Rectal; D000704:Analysis of Variance; D000818:Animals; D002482:Cellulose / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000737:chemistry; D048271:Chitosan / Q000008:administration & dosage* / Q000737:chemistry; D003106:Colon / Q000187:drug effects; D016503:Drug Delivery Systems; D006863:Hydrogen-Ion Concentration; D051381:Rats; D013607:Tablets / Q000008:administration & dosage* / Q000737:chemistry
chemical_list: D013607:Tablets; C013517:ethyl cellulose; D002482:Cellulose; D048271:Chitosan