Real time MRI to elucidate the functionality of coating films intended for modified release
Journal article, 2019

Polymer films based on mixtures of ethyl cellulose (EC) and hydroxypropyl cellulose (HPC) have been widely used to coat pellets and tablets to modify the release profile of drugs. For three different EC/HPC films we used 1H and 19F MRI in combination with a designed release cell to monitor the drug, polymer and water in 5 dimensional (5D) datasets; three spatial, one diffusion or relaxation and a temporal dimension, in real time. We observed that the water inflow through the films correlated with the initiation of the dissolution of the drug in the tablet beneath the film. Leaching of the pore forming HPC further accelerated water penetration and resulted in a drug release onset after a hydrostatic pressure was generated below the film indicated by positional changes of the film. For the more permeable film, both water ingress and drug egress showed a large variability of release over the film surface indicating the heterogeneity of the system. Furthermore, the 1H diffusion dataset revealed the formation of a gel layer of HPC at the film surface. We conclude that the setup presented provides a significant level of details, which are not achieved with traditional methods.


Pore formation

Controlled release

19 F MRI



Drug release


Diana Bernin

Chalmers, Chemistry and Chemical Engineering, Chemical Technology, Chemical Engineering Design

University of Gothenburg

M. Marucci

AstraZeneca AB

Catherine Boissier

AstraZeneca AB

Johan Hjärtstam

AstraZeneca AB

Ulf Olsson

Lund University

Susanna Abrahmsén-Alami

AstraZeneca AB

Journal of Controlled Release

01683659 (ISSN)

Vol. 311-312 117-124

Subject Categories

Polymer Chemistry

Polymer Technologies

Other Chemistry Topics





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