uu.seUppsala University Publications
Change search
ReferencesLink to record
Permanent link

Direct link
Gel formation in systems composed of drug containing catanionic vesicles and oppositely charged hydrophobically modified polymer.
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmacy.
Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry.
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmacy.
2009 (English)In: Colloids and Surfaces B: Biointerfaces, ISSN 0927-7765, E-ISSN 1873-4367, Vol. 70, no 2, 187-197 p.Article in journal (Refereed) Published
Abstract [en]

The aim of this study was to explore if mixtures of drug containing catanionic vesicles and polymers give rise to gel formation, and if so, if drug release from these gels could be prolonged. Catanionic vesicles formed from the drug substances alprenolol or tetracaine, and the oppositely charged surfactant sodium dodecyl sulphate were mixed with polymers. Three polymers with different properties were employed: one bearing hydrophobic modifications, one positively charged and one positively charged polymer bearing hydrophobic modifications. The structure of the vesicles before and after addition of polymer was investigated by using cryo-TEM. Gel formation was confirmed by using rheological measurements. Drug release was studied using a modified USP paddle method. Gels were observed to form only in the case when catanionic vesicles, most likely with a net negative charge, were mixed with positively charged polymer bearing lipophilic modifications. The release of drug substance from these systems, where the vesicles are not trapped within the gel but constitute a founding part of it, could be significantly prolonged. The drug release rate was found to depend on vesicle concentration to a higher extent than on polymer concentration.

Place, publisher, year, edition, pages
2009. Vol. 70, no 2, 187-197 p.
Keyword [en]
Catanionic, vesicle, gel, polymer, prolonged drug release
National Category
Pharmaceutical Sciences
URN: urn:nbn:se:uu:diva-100131DOI: 10.1016/j.colsurfb.2008.12.021ISI: 000265317400005PubMedID: 19167869OAI: oai:DiVA.org:uu-100131DiVA: diva2:209518
Available from: 2009-03-25 Created: 2009-03-25 Last updated: 2011-05-04Bibliographically approved
In thesis
1. Catanionic Aggregates in Gels: Prolonged Drug Release and Potential Implications for Topical Use
Open this publication in new window or tab >>Catanionic Aggregates in Gels: Prolonged Drug Release and Potential Implications for Topical Use
2011 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Gels are popular dosage forms.  This topical dosage form may be advantageous compared to oral or parenteral dosage forms. Favorable rheological or bioadhesive properties of gels might provide extended contact times at the site of administration compared to aqueous solutions. However, due to the high water content of gels, these are usually quickly emptied of the drug substance. One way of prolonging the drug release from gels is to contain the drug substance in catanionic aggregates in the gel. These aggregates are formed in solutions of oppositely charged surfactants and a drug can be used instead of one of the surfactants.


In this thesis catanionic aggregates composed of drug substances and oppositely charged surfactants were studied and the possibility to use these aggregates for the purpose of prolonged drug release was investigated. The formation of catanionic aggregates when using drugs was found to be a common occurrence in addition to which, the oppositely charged surfactant can be varied and surfactants of natural origin with a low toxicity were used. Most combinations tested rendered either vesicles or elongated micelles. When the catanionic aggregates were contained in gels the drug release was substantially prolonged. The apparent diffusion coefficients were lowered 10-100 times compared to the reference gels. When gels with catanionic vesicles with substantial prolonged drug release were applied to skin the penetration rate was lowered extensively. No morphological differences were observed between skin samples that had been exposed to formulations containing catanionic aggregates and skin samples exposed to saline solution, air or formulations containing only the drug. Both conventional, covalently linked pre-formed gels and physical gels, where the catanionic vesicles form the cross-links upon interaction with the polymer, can be used for these purposes. When the effect of drug release on aggregate structure was studied, it was shown that vesicles are present in both conventional and physical gels throughout the drug release process.


This thesis shows that catanionic aggregates contained in gels can present an advantageous formulation strategy to prolong the drug release, thereby improving the efficiency of gel formulations.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2011. 65 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Pharmacy, ISSN 1651-6192 ; 140
National Category
Pharmaceutical Sciences
Research subject
urn:nbn:se:uu:diva-138447 (URN)978-91-554-8019-6 (ISBN)
Public defence
2011-04-15, B 42, BMC, Husargatan 3, Uppsala, 09:15 (Swedish)
Available from: 2011-03-25 Created: 2010-12-17 Last updated: 2011-05-04Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full textPubMed

Search in DiVA

By author/editor
Edwards, Katarina
By organisation
Department of PharmacyDepartment of Physical and Analytical Chemistry
In the same journal
Colloids and Surfaces B: Biointerfaces
Pharmaceutical Sciences

Search outside of DiVA

GoogleGoogle Scholar
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Altmetric score

Total: 414 hits
ReferencesLink to record
Permanent link

Direct link