title: Coated hard capsules as the pH-dependent drug transport systems to ileo-colonic compartment.
abstract: OBJECTIVE
  The aim of this study was to investigate the suitability of hard capsules of different composition (gelatin-G, gelatin coated with hydroxypropyl cellulose-G/HPC, and hypromellose-H) for a coating with aqueous dispersion of pH-dependent synthetic polymer Eudragit(®) FS (E(FS)) and to evaluate in vitro the coated capsules as transport systems for ileo-colonic drug delivery.
  
  
  METHODS
  Three sets of hard capsules with increasing coating levels (5-30%) were obtained by Wurster technique. The release of model drug (caffeine) from prepared samples was tested using paddle dissolution method with continual pH change (pH 1.2-2 h, 6.8-4 h and 7.5-2 h).
  
  
  RESULTS
  During the coating process, no problems occurred and similar suitability of capsules materials for E(FS) application was observed in contrast to some published reports. The application of HPC subcoating onto gelatin capsules surface was shown as the redundant step. The samples G/E(FS)10-15% and H/E(FS)15-20% with 6 h lag time and fast drug release after the pH adjustment to 7.5 corresponded with the requirements for ileic drug delivery. Samples releasing the drug after the pH change to 7.5 in 2-h interval such as G/E(FS) 20%, G/HPC/E(FS) 25% and H/E(FS) 25% are considered as promising transport systems to ileo-colonic area. Samples G/E(FS) 25-30%, G/HPC/E(FS) 30% and H/E(FS) 30% with 7 h lag time could be used for colon delivery.
  
  
  CONCLUSIONS
  The desired intestinal part could be targeted without significant formulation changes only by the selection of capsules shell forming material and suitable E(FS) coating thickness.
authors.affiliation: Department of Pharmaceutics, Faculty of Pharmacy, University of Veterinary and Pharmaceutical Sciences Brno, Czech Republic. dvorackovak@vfu.cz
authors.forename: Kateřina
authors.initials: K
authors.lastname: Dvořáčková
authors.forename: Miloslava
authors.initials: M
authors.lastname: Rabišková
authors.forename: Jan
authors.initials: J
authors.lastname: Muselík
authors.forename: Jan
authors.initials: J
authors.lastname: Gajdziok
authors.forename: Martina
authors.initials: M
authors.lastname: Bajerová
mesh_terms: D001692:Biological Transport; D002110:Caffeine / Q000493:pharmacokinetics*; D002214:Capsules / Q000737:chemistry*; D003106:Colon / Q000378:metabolism*; D003692:Delayed-Action Preparations; D016503:Drug Delivery Systems / Q000379:methods*; D005780:Gelatin / Q000737:chemistry; D006801:Humans; D006863:Hydrogen-Ion Concentration; D065347:Hypromellose Derivatives; D007082:Ileum / Q000378:metabolism*; D008747:Methylcellulose / Q000031:analogs & derivatives / Q000737:chemistry; D011109:Polymethacrylic Acids / Q000737:chemistry; D012995:Solubility; D013997:Time Factors
chemical_list: D002214:Capsules; D003692:Delayed-Action Preparations; D011109:Polymethacrylic Acids; C038300:methylmethacrylate-methacrylic acid copolymer; D002110:Caffeine; D065347:Hypromellose Derivatives; D005780:Gelatin; D008747:Methylcellulose