title: Catanionic aggregates formed from drugs and lauric or capric acids enable prolonged release from gels.
abstract: The aim of this study was to add to the range of charged surfactants that can be used to form catanionic aggregates with oppositely charged surface active drug substances; and to apply these aggregates to prolong drug release from gels. The surfactants used in this study, lauric and capric acids are of natural origin-unlike traditionally used, synthetic, surfactants. The mixtures of drug substances and oppositely charged surfactants were studied visually and with cryogenic transmission electron microscopy. Drug release from gels was studied with a modified USP paddle method. This study shows that lauric and capric acids are as, or even more, active in forming catanionic aggregates than traditionally used surfactants such as sodium dodecyl sulfate. It is shown that the length of the hydrophobic part of the surfactant plays an important role in the formation of pharmaceutically interesting catanionic aggregates. As seen in previous studies, using catanionic vesicles prolongs the drug release from gels and decreases the apparent diffusion coefficient by a factor of 10-50, compared to a gel containing only drug substance.
authors.affiliation: Department of Pharmacy, Uppsala University, Box 580, SE-751 23 Uppsala, Sweden.
authors.forename: Noel
authors.initials: N
authors.lastname: Dew
authors.forename: Tobias
authors.initials: T
authors.lastname: Bramer
authors.forename: Katarina
authors.initials: K
authors.lastname: Edsman
mesh_terms: D000362:Agar / Q000737:chemistry; D002412:Cations; D002626:Chemistry, Pharmaceutical / Q000379:methods*; D020285:Cryoelectron Microscopy / Q000379:methods; D003652:Decanoic Acids / Q000737:chemistry*; D003692:Delayed-Action Preparations / Q000737:chemistry*; D004058:Diffusion; D005782:Gels; D007850:Lauric Acids / Q000737:chemistry*; D046529:Microscopy, Electron, Transmission; D012967:Sodium Dodecyl Sulfate / Q000737:chemistry; D013499:Surface Properties; D013501:Surface-Active Agents; D013678:Technology, Pharmaceutical / Q000379:methods*; D013748:Tetracaine / Q000494:pharmacology
chemical_list: D002412:Cations; D003652:Decanoic Acids; D003692:Delayed-Action Preparations; D005782:Gels; D007850:Lauric Acids; D013501:Surface-Active Agents; D013748:Tetracaine; C030358:lauric acid; D012967:Sodium Dodecyl Sulfate; C031071:decanoic acid; D000362:Agar