title: Magnetic resonance microscopy for assessment of morphological changes in hydrating hydroxypropylmethyl cellulose matrix tablets in situ.
abstract: OBJECTIVE
  To resolve contradictions found in morphology of hydrating hydroxypropylmethyl cellulose (HPMC) matrix as studied using Magnetic Resonance Imaging (MRI) techniques. Until now, two approaches were used in the literature: either two or three regions that differ in physicochemical properties were identified.
  
  
  METHODS
  Multiparametric, spatially and temporally resolved T(2) MR relaxometry in situ was applied to study the hydration progress in HPMC matrix tablets using a 11.7 T MRI system. Two spin-echo based pulse sequences-one of them designed to specifically study short T(2) signals-were used.
  
  
  RESULTS
  Two components in the T(2) decay envelope were estimated and spatial distributions of their parameters, i.e. amplitudes and T(2) values, were obtained. Based on the data, five different regions and their temporal evolution were identified: dry glassy, hydrated solid like, two interface layers and gel layer. The regions were found to be separated by four evolving fronts identified as penetration, full hydration, total gelification and apparent erosion.
  
  
  CONCLUSIONS
  The MRI results showed morphological details of the hydrating HPMC matrices matching compound theoretical models. The proposed method will allow for adequate evaluation of controlled release polymeric matrix systems loaded with drug substances of different solubility.
authors.affiliation: Department of Magnetic Resonance Imaging, Institute of Nuclear Physics PAN, ul. Radzikowskiego 152, 31-342 Kraków, Poland. Piotr.Kulinowski@ifj.edu.pl
authors.forename: Piotr
authors.initials: P
authors.lastname: Kulinowski
authors.forename: Anna
authors.initials: A
authors.lastname: Młynarczyk
authors.forename: Przemysław
authors.initials: P
authors.lastname: Dorożyński
authors.forename: Krzysztof
authors.initials: K
authors.lastname: Jasiński
authors.forename: Marco L H
authors.initials: ML
authors.lastname: Gruwel
authors.forename: Bogusław
authors.initials: B
authors.lastname: Tomanek
authors.forename: Władysław P
authors.initials: WP
authors.lastname: Węglarz
mesh_terms: D065347:Hypromellose Derivatives; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008747:Methylcellulose / Q000031:analogs & derivatives* / Q000737:chemistry; D008853:Microscopy / Q000379:methods; D013607:Tablets / Q000737:chemistry; D014867:Water / Q000737:chemistry*
chemical_list: D013607:Tablets; D014867:Water; D065347:Hypromellose Derivatives; D008747:Methylcellulose