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Catanionic mixtures formed from drugs and lauric or capric acid enable prolonged release from gels
Uppsala University, Medicinska vetenskapsområdet, Faculty of Pharmacy, Department of Pharmacy.
Article in journal (Refereed) Submitted
URN: urn:nbn:se:uu:diva-96415OAI: oai:DiVA.org:uu-96415DiVA: diva2:170982
Available from: 2007-11-16 Created: 2007-11-16Bibliographically approved
In thesis
1. Prolonged Drug Release from Gels, using Catanionic Mixtures
Open this publication in new window or tab >>Prolonged Drug Release from Gels, using Catanionic Mixtures
2007 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The use of catanionic drug-surfactant mixtures was proven to be an efficient novel method of obtaining prolonged drug release from gels. It was shown that various commonly used drug compounds are able to form catanionic mixtures together with oppositely charged surfactants. These mixtures exhibited interesting phase behaviour, where, among other structures, vesicles and large worm-like or branched micelles were found. The size of these aggregates makes them a potential means of prolonging the drug release from gels, as only monomer drugs in equilibrium with larger aggregates were readily able to diffuse through the gel. When the diffusion coefficient for drug release from the formulation based upon a catanionic mixture was compared to that obtained for the drug substance and gel alone, the coefficient was some 10 to 100 times smaller.

The effects of changes in the pH and ionic strength on the catanionic aggregates was also investigated, and this method of prolonging the release was found to be quite resilient to variations in both. Although the phase behaviour was somewhat affected, large micelles and vesicles were still readily found. The drug release was significantly prolonged even under physiological conditions, that is, at a pH of 7.4 and an osmolality corresponding to 0.9% NaCl.

Surfactants of low irritancy, capric and lauric acid, may successfully be used instead of the more traditional surfactants, such as sodium lauryl sulfate (SDS), and prolonged release can still be obtained with ease.

Some attempts to deduce the release mechanism from the proposed systems have also been made using transient current measurements, dielectric spectroscopy, and modelling of the release using the regular solution theory. In these studies, the previous assumptions made concerning the mechanism responsible for the release were confirmed to a large extent. Only small amounts of the drug existed in monomer form, and most seemed to form large catanionic aggregates with the oppositely charged surfactant.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2007. 66 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Pharmacy, ISSN 1651-6192 ; 65
Pharmaceutics, gel, catanionic, vesicle, micelle, controlled release, diffusion, surfactant, drug delivery, Galenisk farmaci
urn:nbn:se:uu:diva-8303 (URN)978-91-554-7017-3 (ISBN)
Public defence
2007-12-07, B42, BMC, Husargatan 3, Uppsala, 09:15
Available from: 2007-11-16 Created: 2007-11-16Bibliographically approved

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