title: Polymer film formulations for the preparation of enteric pharmaceutical capsules.
abstract: OBJECTIVE
  Standard pharmaceutical capsules are designed to dissolve in the acidic environment of the stomach releasing the encapsulated contents for absorption. When release is required further along the gastrointestinal tract capsules can be coated with acid insoluble polymers to enable passage through the stomach and dissolution in the intestine. This paper describes formulations that have the potential to be used to produce two-piece hard capsules for post-gastric delivery without the requirement of an exterior coat.
  
  
  METHODS
  The formulation uses three polysaccharides: sodium alginate, hypromellose and gellan gum to provide acid insolubility and the ability to form capsules using standard industrial equipment.
  
  
  RESULTS
  The rheological profile, on cooling, of the base material, water content and thickness of the films were shown to be comparable with those of commercial capsules. The capsules remained intact for 2 h in 100 mm HCl at pH 1.2, and within 5 min of being removed from the acid and submerged in phosphate-buffered saline at pH 6.8 were ruptured.
  
  
  CONCLUSIONS
  Selected formulations from this study have potential for use as delayed release capsules.
authors.affiliation: School of Chemical Engineering, University of Birmingham, Birmingham, UK. a.m.smith@bham.ac.uk
authors.forename: Alan M
authors.initials: AM
authors.lastname: Smith
authors.forename: Andrew
authors.initials: A
authors.lastname: Ingham
authors.forename: Liam M
authors.initials: LM
authors.lastname: Grover
authors.forename: Yvonne
authors.initials: Y
authors.lastname: Perrie
mesh_terms: D000464:Alginates / Q000737:chemistry*; D002214:Capsules; D002626:Chemistry, Pharmaceutical / Q000379:methods*; D020723:Glucuronic Acid / Q000737:chemistry; D006603:Hexuronic Acids / Q000737:chemistry; D006851:Hydrochloric Acid / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D065347:Hypromellose Derivatives; D008747:Methylcellulose / Q000031:analogs & derivatives* / Q000737:chemistry; D011108:Polymers / Q000737:chemistry*; D011135:Polysaccharides, Bacterial / Q000737:chemistry*; D012212:Rheology; D012995:Solubility; D013608:Tablets, Enteric-Coated / Q000737:chemistry*
chemical_list: D000464:Alginates; D002214:Capsules; D006603:Hexuronic Acids; D011108:Polymers; D011135:Polysaccharides, Bacterial; D013608:Tablets, Enteric-Coated; D065347:Hypromellose Derivatives; C048288:gellan gum; D020723:Glucuronic Acid; D008747:Methylcellulose; D006851:Hydrochloric Acid