The influence of the molecular weight of the water-soluble polymer on phase-separated films for controlled release
Journal article, 2016
Hydroxypropyl cellulose (HPC) and ethyl cellulose (EC) can be used for extended release coatings, where the water-soluble HPC may act as a pore former. The aim was to investigate the effect of the molecular weight of HPC on the microstructure and mass transport in phase-separated freestanding EC/HPC films with 30% w/w HPC. Four different HPC grades were used, with weight averaged molecular weights (Mw) of 30.0 (SSL), 55.0 (SL), 83.5 (L) and 365 (M) kg/mol. Results showed that the phase-separated structure changed from HPC-discontinuous to bicontinuous with increasing Mw of HPC. The film with the lowest Mw HPC (SSL) had unconnected oval-shaped HPC-rich domains, leaked almost no HPC and had the lowest water permeability. The remaining higher Mw films had connected complex-shaped pores, which resulted in higher permeabilities. The highest Mw film (M) had the smallest pores and very slow HPC leakage, which led to a slow increase in permeability. Films with grade L and SL released most of their HPC, yet the permeability of the L film was three times higher due to greater pore connectivity. It was concluded that the phase-separated microstructure, the level of pore percolation and the leakage rate of HPC will be affected by the choice of HPC Mw grade used in the film and this will in turn have strong impact on the film permeability.
Pellet formulation
Controlled release
Hydroxypropyl cellulose
Phase separation
Molecular weight
Film coating
Ethyl cellulose
Author
Helene Andersson
Chalmers, Materials and Manufacturing Technology, Polymeric Materials and Composites
SuMo Biomaterials
Henrike Häbel
Chalmers, Mathematical Sciences, Mathematical Statistics
University of Gothenburg
SuMo Biomaterials
Anna Olsson
Chalmers, Physics, Eva Olsson Group
SuMo Biomaterials
Sofie Sandhagen
Chalmers, Chemistry and Chemical Engineering
Christian von Corswant
AstraZeneca AB
Johan Hjärtstam
AstraZeneca AB
Michael Persson
Chalmers, Chemistry and Chemical Engineering
Mats Stading
Chalmers, Materials and Manufacturing Technology, Polymeric Materials and Composites
Anette Larsson
Chalmers, Chemistry and Chemical Engineering, Applied Chemistry
SuMo Biomaterials
International Journal of Pharmaceutics
0378-5173 (ISSN) 1873-3476 (eISSN)
Vol. 511 1 223-235Subject Categories
Other Physics Topics
Biomaterials Science
Infrastructure
Chalmers Materials Analysis Laboratory
Areas of Advance
Materials Science
DOI
10.1016/j.ijpharm.2016.06.058