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Finite element analysis of the release of slowly dissolving drugs from cylindrical matrix systems
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmacy.
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
2005 (English)In: Journal of Controlled Release, ISSN 0168-3659, E-ISSN 1873-4995, Vol. 107, no 2, 320-329 p.Article in journal (Refereed) Published
Abstract [en]

Drug release from matrix systems of cylindrical shape is analyzed in detail by using the finite element method. The model used combines the Noyes-Whitney and diffusion equations, and thus takes the effects of a finite dissolution rate into account. The model is valid for all drug solubilities and dissolution rates, and allows accurate predictions of the drug release to be made. Anisotropic drug transport that may result from the manufacturing process is properly accounted for. Model calculations show that a finite dissolution rate may affect the release profile significantly, producing an initial delay. The equivalence between anisotropic release and isotropic release from a matrix with different dimensions is demonstrated. Comparisons are made with the predictions of a recently proposed pseudo-steady state (PSS) analysis of drug release from cylindrical matrices [Y. Zhou, J. S. Chu, T. Zhou, X. Y. Wu, Modeling of dispersed-drug release from two-dimensional matrix tablets, Biomaterials 26 (2005) 945-952]. This comparison reveals that important discrepancies exist between the numerical and analytical results, which are attributed to the simplifying assumption made in the PSS analysis that the region containing solid drug remains cylindrical in shape throughout the release process. The proposed model is shown to describe experimental release data well.

Place, publisher, year, edition, pages
2005. Vol. 107, no 2, 320-329 p.
National Category
Medical and Health Sciences
URN: urn:nbn:se:uu:diva-95752DOI: 10.1016/j.jconrel.2005.06.016PubMedID: 16081182OAI: oai:DiVA.org:uu-95752DiVA: diva2:170083
Available from: 2007-04-13 Created: 2007-04-13 Last updated: 2015-09-09Bibliographically approved
In thesis
1. Drug Diffusion and Nano Excipient Formation Studied by Electrodynamic Methods
Open this publication in new window or tab >>Drug Diffusion and Nano Excipient Formation Studied by Electrodynamic Methods
2007 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

New smart drugs demand new smart drug delivery systems and also new smart analysis methods for the drug delivery process and material characterization. This thesis contributes to the field by introducing a new electrodynamic approach for studying the drug diffusion proc-esses as well as the formation of a new type of drug delivery systems, the so called mesoporous nano excipients.

Drug diffusion processes from different pharmaceutical materials were examined. The transport of charged drug substances was investigated by electrodynamic methods; either as a release process governed by diffusion using the alternating ionic current method or by applying a voltage, sinusoidal or dc, to force the drug ions to move in an electric field.

Temperature-dependent drug release from microcrystalline cellulose tablets was examined in order to extract information about the diffu-sion process. Percolation theory was also employed to binary mixtures of an insoluble and electrically insulating matrix material together with a soluble and ionic conducting drug. Further, dielectric spectros-copy was proven to be a powerful method for examining the state of vesicle formation of drug and surfactant molecules in a carbopol gel. Finally, a new potential class of pharmaceutical materials were exam-ined, namely the AMS-n mesoporous materials, showing that the al-ternating ionic current method is powerful both in the study of the synthesis of and in the release process from these.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2007. 73 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 293
Functional materials, drug release, electrodynamic methods, diffusion, Funktionella material
urn:nbn:se:uu:diva-7818 (URN)978-91-554-6864-4 (ISBN)
Public defence
2007-05-07, 2001, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 13:00
Available from: 2007-04-13 Created: 2007-04-13 Last updated: 2015-09-11Bibliographically approved

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Frenning, GöranStrømme, Maria
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