Shah, S. S. ; Kulkarni, M. G. ; Mashelkar, R. A. (1991) pH dependent zero order release from glassy hydrogels: penetration vs. diffusion control Journal of Controlled Release, 15 (2). pp. 121-131. ISSN 0168-3659
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Official URL: http://linkinghub.elsevier.com/retrieve/pii/016836...
Related URL: http://dx.doi.org/10.1016/0168-3659(91)90070-T
Abstract
Release of low molecular weight solutes from glassy hydrogels is known to follow zero order kinetics. Enhanced swelling brought about by the polymer-penetrant interaction enables the release of bulkier drugs such as caffeine to take place at a constant rate. The release in both the cases has been attributed in the past to the case II transport controlled penetration of the surrounding medium. This work reports pH dependent release of theophylline and carbamazepine from glassy poly(2-hydroxyethyl methacrylate-co-4-carboxy styrene), P(HEMA-4CS) hydrogels. Zero order release observed at pH 11.0 is consistent with an increase in the diffusivity of the active ingredient due to the enhanced swelling rather than case II transport controlled penetration of the medium.
| Item Type: | Article |
|---|---|
| Source: | Copyright of this article belongs to Controlled Release Society. |
| Keywords: | Glassy Polymers; Ionic Hydrogels; Swellable Polymers; Time Dependent Diffusion Coefficient; Zero Order Release |
| ID Code: | 17042 |
| Deposited On: | 16 Nov 2010 08:40 |
| Last Modified: | 04 Jun 2011 08:30 |
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