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Percolative drug diffusion from cylindrical matrix systems with unsealed boundaries
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials. (Nanoteknologi och funktionella material)
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials. (Nanoteknologi och funktionella material)ORCID iD: 0000-0002-5496-9664
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmacy.
2007 (English)In: Journal of Pharmaceutical Sciences, ISSN 0022-3549, E-ISSN 1520-6017, Vol. 96, no 11, 3087-3099 p.Article in journal (Refereed) Published
Abstract [en]

Release of NaCl in both the axial and radial directions from cylindrical ethyl cellulose tablets were investigated by the alternating ionic current method. The pore structure of the investigated binary mixtures was examined by mercury porosimetry and scanning electron microscopy, and the nm range fractal surface dimension of tablet pore walls was extracted from krypton gas adsorption isotherms. The drug release was shown to consist of two overlapping processes of which the first was ascribed to dissolution of NaCl close to the tablet boundary followed by subsequent diffusion through a thin ethyl cellulose layer and a second from which a porosity percolation threshold of 0.22 could be extracted. As well, a cross-over to effective-medium behaviour at a porosity of 0.44 was observed. The presented findings showed that drug release from matrix tablets with unsealed tablet walls substantially differs from earlier investigated release processes for which the drug has only been allowed to escape through one of the flat tablet surfaces. Thus, the present study brings forward knowledge important for the tailoring of controlled drug delivery vehicles with optimum release patterns.

Place, publisher, year, edition, pages
2007. Vol. 96, no 11, 3087-3099 p.
Keyword [en]
adsorption, structure-transport relationship, polymeric drug delivery systems, drug transport, controlled release
National Category
Engineering and Technology Pharmaceutical Sciences
Identifiers
URN: urn:nbn:se:uu:diva-95753DOI: 10.1002/jps.20915ISI: 000250618700020PubMedID: 17721939OAI: oai:DiVA.org:uu-95753DiVA: diva2:170084
Available from: 2007-04-13 Created: 2007-04-13 Last updated: 2017-12-14Bibliographically 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.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 293
Keyword
Functional materials, drug release, electrodynamic methods, diffusion, Funktionella material
Identifiers
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
Opponent
Supervisors
Available from: 2007-04-13 Created: 2007-04-13 Last updated: 2015-09-11Bibliographically approved

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Brohede, UlrikaValizadeh, SimaStrømme, MariaFrenning, Göran

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