Abstract
Purpose. The purpose of this study was to characterise the water mobility in the gel layer of hydrating HPMC tablets. Water mobility in the gel layer of different HPMCs was studied.
Methods. NMR imaging, a non-invasive technique, has been used to measure the spatial distribution of self-diffusion coefficient (SDC) and T2 relaxation times across the gel layer.
Results. It has been shown that there is a water mobility gradient across the gel layer of HPMC tablets. Although SDC and T2 relaxation times in the outer parts of the gel layer approached that of free water, in the inner parts they decreased progressively. Water mobility and SDC in the gel layer of different HPMCs appeared to vary with degree of substitution of the polymer and the lowest values were obtained across the gel layer of K4M tablets.
Conclusions. Water mobility varies across the gel layer of hydrating HPMC tablets and it is dependent on the degree of substitution of the polymer.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
REFERENCES
C. D. Melia, Hydrophilic matrix sustained release systems based on polysaccharides carriers. Crit. Rev. Ther. Drug Carrier Systems 8:395–421 (1991).
C. D. Melia, A. C. Hodsdon, M. C. Davies, J. R. Mitchell, Polymer concentration profiles of the surface gel layer of xanthan, alginate and HPMC matrix systems. Proceed. Intern. Symp. Control. Rel. Bioact. Mater. 21:724–725 (1994).
C. D. Melia, J. S. Binns, M. C. Davies, Polymer hydration and drug distribution within the gel layer of hydrophilic matrix devices during drug release. J. Pharm. Pharmacol. 42:125P (1990).
A. C. Hodsdon, J. R. Mitchell, M. C. Davies, C. D. Melia, Structure and behaviour in hydrophilic matrix sustained release dosage forms: 3. The influence of pH on the sustained-release performance and internal gel structure of sodium alginate matrices. J. Controlled Release 33:143–152 (1995).
C. D. Melia, A. R. Rajabi-Siahboomi, A. C. Hodsdon, J. Adler and J. R. Mitchell, Structure and behaviour in hydrophilic matrix sustained release dosage forms: 1. The origin and mechanism of formation of gas bubbles in the hydrated surface layer. Int. J. Pharm. 100:263–269 (1994).
R. W. Korsmeyer, E. D. Von Meerwall and N. A. Peppas, Diffusion in swellable drug delivery systems. Proceed. Intern. Symp. Control. Rel. Bioact. Mater. 12:81–82 (1985).
A. R. Rajabi-Siahboomi, R. W. Bowtell, P. Mansfield, A. Henderson, M. C. Davies and C. D. Melia, Structure and behaviour in hydrophilic matrix sustained release dosage forms: 2. NMR-imaging studies of dimensional changes in the gel layer and core of HPMC matrices undergoing hydration. J. Controlled Release 31:121–128 (1994).
R. W. Bowtell, J. C. Sharp, A. Peters, P. Mansfield, A. R. Rajabi-Siahboomi, M. C. Davies and C. D. Melia, NMR Microscopy of hydrating hydrophilic matrix pharmaceutical tablets. Mag. Res., Imaging 12:361–364 (1994).
R. A. Meyer and T. R. Brown, Diffusion measurements by microscopic NMR imaging. J. Mag. Res. 76:393–399 (1988).
L. A. Weisenberger and J. L Koenig, NMR imaging of diffusion processes in polymers: Measurement of spatial dependence of solvent mobility in partially swollen PMMA rods. Macromolecules 23:2445–2453 (1990).
D. Hariharan, N. A. Peppas, Modelling of water transport and solute release in physiologically sensitive gels. J. Controlled Release 23:123–136 (1993).
A. R. Rajabi-Siahboomi, M. C. Davies and C. D. Melia, Probing the hydration of the surface gel layer in HPMC hydrophilic matrices. In “Proceedings 1st UKaps Conf.” 1992 Eds Hadgraft J., Kellaway I. W., Parr G. D. STS Publishing, Cardiff, UK pp 34.
D. A. Alderman, A review of cellulose ethers in hydrophilic matrices for oral controlled release dosage forms. Int. J. Pharm. Tech. Prod. Mft. 5:1–9 (1984).
P. Colombo, P. L Catellani, N. A. Peppas, L. Maggi and U. Conte, Swelling characteristics of hydrophilic matrices for controlled release: New dimensionless number to describe the swelling and release behaviour. Int. J. Pharm. 88:99–109 (1992).
K. Mitchell, J. Ford, C. Rostron, D. Armstrong, P. Elliott and J. Hogan, Swelling behaviour of cellulose ether matrix tablets. J. Pharm. Pharmacol. Suppl. 43:77P (1991).
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Rajabi-Siahboomi, A.R., Bowtell, R.W., Mansfield, P. et al. Structure and Behavior in Hydrophilic Matrix Sustained Release Dosage Forms: 4. Studies of Water Mobility and Diffusion Coefficients in the Gel Layer of HPMC Tablets Using NMR Imaging. Pharm Res 13, 376–380 (1996). https://doi.org/10.1023/A:1016084224084
Issue Date:
DOI: https://doi.org/10.1023/A:1016084224084