The effect of substitution pattern of HPMC on polymer release from matrix tablets
Journal article, 2010

The purpose of this study was to gain further understanding of how the substituent heterogeneity of hydroxypropyl methylcellulose, HPMC, affects the polymer release from hydrophilic matrix tablets. The hypothesis was that the heterogeneous substituent pattern facilitated hydrophobic interactions that increased the viscosity and therefore affected the release rate to a major extent. Polymer tablets were prepared from three heterogeneously substituted HPMC batches of the same substituent (2208) and viscosity (100 cps) grade. To elucidate the hypothesis, fractions of both the dissolved polymer and the tablet residue were collected from the dissolution bath and further characterised. The extensive characterisation showed that, although the dissolved bath fraction and the tablet residue had a similar average degree of substitution, the residue was more heterogeneously substituted. It was further revealed that the heterogeneous substituent pattern of the tablet residue facilitated the formation of soluble gel-like components already at room temperature, which increased the viscosity. The viscosity increased by 150% at temperatures correlated to the dissolution bath, and it was thus concluded that the gel-like components grew in size with temperature. Finally, much lower release rates were obtained by tablets composed of the residue compared to tablets composed of the bath fraction, which clarified the hypothesis.

Hydrophilic matrix tablets

Substituent pattern

Chemical

characterisation

Hydroxypropyl methylcellulose

Enzymatic characterisation

Author

Anna Viridén

SuMo Biomaterials

Chalmers, Chemical and Biological Engineering, Pharmaceutical Technology

Anette Larsson

SuMo Biomaterials

Chalmers, Chemical and Biological Engineering, Pharmaceutical Technology

Bengt Wittgren

AstraZeneca AB

International Journal of Pharmaceutics

0378-5173 (ISSN) 1873-3476 (eISSN)

Vol. 389 1-2 147-156

Subject Categories

Pharmaceutical Sciences

DOI

10.1016/j.ijpharm.2010.01.029

More information

Latest update

8/18/2020