title: Distribution of local anesthetics between aqueous and liposome phases.
abstract: Liposomes were used as biomimetic models in capillary electrokinetic chromatography (EKC) for the determination of distribution constants (KD) of certain local anesthetics and a commonly used preservative. Synthetic liposomes comprised phosphatidylcholine and phosphatidylglycerol phospholipids with and without cholesterol. In addition, ghost liposomes made from red blood cell (RBC) lipid extracts were used as pseudostationary phase to acquire information on how the liposome composition affects the interactions between anesthetics and liposomes. These results were compared with theoretical distribution coefficients at pH 7.4. In addition to 25°C, the distribution constants were determined at 37 and 42°C to simulate physiological conditions. Moreover, the usability of five electroosmotic flow markers in liposome (LEKC) and micellar EKC (MEKC) was studied. LEKC was proven to be a convenient and fast technique for obtaining data about the distribution constants of local anesthetics between liposome and aqueous phase. RBC liposomes can be utilized for more representative model of cellular membranes, and the results indicate that the distribution constants of the anesthetics are greatly dependent on the used liposome composition and the amount of cholesterol, while the effect of temperature on the distribution constants is less significant.
authors.affiliation: Department of Chemistry, POB 55, 00014 University of Helsinki, Finland.
authors.forename: Suvi-Katriina
authors.initials: SK
authors.lastname: Ruokonen
authors.affiliation: Department of Chemistry, POB 55, 00014 University of Helsinki, Finland; Institute of Analytical Chemistry of the CAS, v. v. i., Brno, Czechia.
authors.forename: Filip
authors.initials: F
authors.lastname: Duša
authors.affiliation: Department of Chemistry, POB 55, 00014 University of Helsinki, Finland.
authors.forename: Antti H
authors.initials: AH
authors.lastname: Rantamäki
authors.affiliation: Helsinki Eye Lab, Ophthalmology, University of Helsinki and Helsinki University Hospital, Finland.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Robciuc
authors.affiliation: Department of Chemistry, POB 55, 00014 University of Helsinki, Finland.
authors.forename: Paula
authors.initials: P
authors.lastname: Holma
authors.affiliation: Helsinki Eye Lab, Ophthalmology, University of Helsinki and Helsinki University Hospital, Finland.
authors.forename: Juha M
authors.initials: JM
authors.lastname: Holopainen
authors.affiliation: Department of Environmental Science and Analytical Chemistry, Stockholm University, Sweden.
authors.forename: Mohamed
authors.initials: M
authors.lastname: Abdel-Rehim
authors.affiliation: Department of Chemistry, POB 55, 00014 University of Helsinki, Finland. Electronic address: susanne.wiedmer@helsinki.fi.
authors.forename: Susanne K
authors.initials: SK
authors.lastname: Wiedmer
mesh_terms: D000779:Anesthetics, Local / Q000737:chemistry*; D020374:Chromatography, Micellar Electrokinetic Capillary; D004912:Erythrocytes / Q000378:metabolism; D006801:Humans; D008012:Lidocaine / Q000737:chemistry; D008051:Lipid Bilayers / Q000737:chemistry; D008081:Liposomes / Q000737:chemistry*; D010713:Phosphatidylcholines / Q000737:chemistry; D010743:Phospholipids / Q000737:chemistry / Q000302:isolation & purification; D013696:Temperature; D014867:Water / Q000737:chemistry*
chemical_list: D000779:Anesthetics, Local; D008051:Lipid Bilayers; D008081:Liposomes; D010713:Phosphatidylcholines; D010743:Phospholipids; D014867:Water; D008012:Lidocaine
keywords: Cholesterol; Distribution constants; EOF markers; Liposome electrokinetic chromatography; Local anesthetics; Red blood cell lipids