title: Simultaneous FTIR spectroscopic imaging and visible photography to monitor tablet dissolution and drug release.
abstract: OBJECTIVE
  Previous studies of hydroxypropyl methylcellulose (HPMC)-based tablet during exposure to water showed a number of 'fronts' moving into the tablet but led to contradictory interpretations. These fronts are related to water penetration into and dissolution of the tablet, but the exact nature can not be derived from visible photographic evidence. A method to study tablet dissolution simultaneously by Fourier transform infrared-attenuated total reflection (FTIR-ATR) imaging and macro-photography can assist in providing correct interpretation of the observed fronts.
  
  
  METHODS
  Therefore, the combination of macro-photography and FTIR-ATR spectroscopic imaging was developed and used to interpret the physical changes leading to the observed fronts. Buflomedyl pyridoxal phosphate (BPP), a coloured drug, was used as a model drug.
  
  
  RESULTS
  The quantitative results obtained by FTIR-ATR imaging enabled the attribution of the three observed fronts (inside to outside) to: (1) true water penetration, possibly combined with (partial) dissolution of buflomedyl pyridoxal phosphate (BPP); (2) total gellification of HPMC; (3) erosion front.
  
  
  CONCLUSIONS
  The method to study dissolution of a tablet simultaneously by FTIR-ATR imaging and macro-photography has been developed and used to obtain reliable interpretation of the fronts observed during tablet dissolution.
authors.affiliation: Department of Chemical Engineering, Imperial College London, London, SW7 2AZ, UK. s.kazarian@imperial.ac.uk
authors.forename: Sergei G
authors.initials: SG
authors.lastname: Kazarian
authors.forename: Jaap
authors.initials: J
authors.lastname: van der Weerd
mesh_terms: D004337:Drug Carriers; D065347:Hypromellose Derivatives; D007090:Image Interpretation, Computer-Assisted; D007368:Interferometry; D008027:Light; D008747:Methylcellulose / Q000031:analogs & derivatives* / Q000737:chemistry; D010781:Photography; D011759:Pyrrolidines / Q000737:chemistry*; D015203:Reproducibility of Results; D012995:Solubility; D017550:Spectroscopy, Fourier Transform Infrared; D013607:Tablets; D013678:Technology, Pharmaceutical / Q000379:methods*; D013997:Time Factors; D014867:Water / Q000737:chemistry
chemical_list: D004337:Drug Carriers; D011759:Pyrrolidines; D013607:Tablets; D014867:Water; D065347:Hypromellose Derivatives; D008747:Methylcellulose; C010651:buflomedil