title: Characterization of temperature-dependent drug release from liposomes using electron spin resonance.
abstract: Liposome blood clearance and temperature-dependent drug release were studied using an electron spin resonance technique on whole blood samples. Temperature-sensitive liposomes composed of dipalmitoylphosphatidylcholine and dipalmitoylphosphatidylglycerol (4:1 by weight) were formed by reversed-phase evaporation. The liposomes were stable in the blood for greater than 2 h after iv injection. Liposome blood clearance exhibited a fast and slow component which may be due to the presence of both large and small liposomes in the preparation. The onset temperature for liposome release of the water-soluble nitroxide spin label was reduced from 40 degrees C in Hepes buffered saline to 38 degrees C in the rat blood, and the total release in the blood was approximately 25% greater than that measured in saline. These results show the influence of blood constituents on temperature-dependent drug release from liposomes.
authors.affiliation: Department of Electrical and Computer Engineering, University of Illinois, Urbana 61801.
authors.forename: H C
authors.initials: HC
authors.lastname: Chan
authors.forename: R L
authors.initials: RL
authors.lastname: Magin
mesh_terms: D015060:1,2-Dipalmitoylphosphatidylcholine / Q000032:analysis / Q000097:blood; D000818:Animals; D004578:Electron Spin Resonance Spectroscopy; D008081:Liposomes / Q000032:analysis* / Q000097:blood; D010316:Particle Size; D004364:Pharmaceutical Preparations / Q000032:analysis* / Q000097:blood; D010715:Phosphatidylglycerols / Q000032:analysis / Q000097:blood; D051381:Rats; D013696:Temperature
chemical_list: D008081:Liposomes; D004364:Pharmaceutical Preparations; D010715:Phosphatidylglycerols; D015060:1,2-Dipalmitoylphosphatidylcholine; C030345:1,2-dipalmitoylphosphatidylglycerol