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Controlled Drug Release from Gels Using Lipophilic Interactions of Charged Substances with Surfactants and Polymers
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmacy.
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmacy.
2002 (English)In: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 248, no 1, 194-200 p.Article in journal (Refereed) Published
Description
Abstract [en]

The aim of this article was to study interactions between different gel forming polymers and amphiphilic drugs and surfactants with the intention of finding interactions that can be used for designing controlled release formulations. The release from gels was measured by detecting the UV-absorbance of drugs released from 6 mL gel into 250 mL release medium in a dissolution bath. The rheological behavior of gels was characterized using a controlled rate rheometer. The diffusion coefficient of alprenolol was 6.3 x 10(-6) cm(2)/s when formulated in a 1% poly(acrylic acid) gel (PAA) and 2.8 x 10(-6) cm(2)/s in a lipophilically modified gel (LM-PAA). The addition of alprenolol to 1% LM-PAA increased the elasticity, G', from 123 to 182 Pa. Increased gel strength was also observed for a number of other amphiphilic drugs. The addition of 1% Brij 58 to LM-PAA decreased the diffusion coefficient of alprenolol to 2.3 x 10(-6) cm(2)/s. It was possible to sustain the release of charged drugs with high log P by adding surfactant micelles. However, the effect was small and only useful for drugs with adequate lipophilicity. The interaction between LM-PAA and amphiphilic drugs could be seen using rheology and was used for designing controlled release gel formulations. In this way surfactants can be avoided, thus decreasing toxicity problems.

Place, publisher, year, edition, pages
2002. Vol. 248, no 1, 194-200 p.
National Category
Medical and Health Sciences
Identifiers
URN: urn:nbn:se:uu:diva-89522DOI: 10.1006/jcis.2001.8182PubMedID: 16290522OAI: oai:DiVA.org:uu-89522DiVA: diva2:161063
Available from: 2001-11-15 Created: 2001-11-15 Last updated: 2017-06-09Bibliographically approved
In thesis
1. Controlled Release Gel Formulations for Mucosal Drug Delivery
Open this publication in new window or tab >>Controlled Release Gel Formulations for Mucosal Drug Delivery
2001 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Drug delivery to nasal or ocular mucosa for either local or systemic action faces many obstacles – these routes are protected by effective mechanisms. Gel formulations with suitable rheological and mucoadhesive properties increase the contact time at the site of absorption. However, drug release from the gel must be sustained if benefits are to be gained from the prolonged contact time.

The work presented here is the characterization of gels and the determination of the mucoadhesive properties of polymers using rheology. Gelrite gels were formed in simulated tear fluid at concentrations of polymer as low as 0.1%, and it was shown that sodium was the most important gel-promoting ion in vivo. Rheology, although it may be a questionable technique for evaluating mucoadhesive properties of polymers, showed that interactions between mucin and polymers were most likely to be seen with weak gels.

It was possible to control the release of uncharged drug substances by including surfactants that form micelles in the gel. This release depended on lipophilic interactions between the drug and the polymer and/or the micelles. Controlled-release formulations of charged drugs could be designed by mixing the drugs with oppositely charged surfactants in certain ratios. In this way, vesicles in which the drug and surfactant constituted the bilayer formed spontaneously. The vesicle formation was affected by the presence of polymer, and very small vesicles that gave a slow release rate were formed when a lipophilically modified polymer was used.

The gels were also evaluated in the Ussing chamber using porcine nasal mucosa. The rate of transport of drugs through the mucosa could be controlled by the rate of release from the formulation. Furthermore, the Ussing chamber could be used to evaluate the potential toxicity of formulations.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2001. 52 p.
Series
Comprehensive Summaries of Uppsala Dissertations from the Faculty of Pharmacy, ISSN 0282-7484 ; 259
Keyword
Pharmacy, FARMACI
National Category
Pharmaceutical Sciences
Research subject
Pharmaceutics
Identifiers
urn:nbn:se:uu:diva-1493 (URN)91-554-5173-X (ISBN)
Public defence
2001-12-07, B42, BMC, Uppsala, 09:15
Opponent
Available from: 2001-11-15 Created: 2001-11-15 Last updated: 2013-06-12Bibliographically approved

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