title: Study of the diclofenac/phospholipid interactions with liposomes and monolayers.
abstract: The interaction of diclofenac sodium (SD) with soya phosphatidylcholine (SPC) has been studied with floating Langmuir monolayers and liposomes. SD was either introduced into the subphase of SPC monolayers or co-spread with SPC on an aqueous subphase. In both cases, SD caused the surface pressure isotherm to become more expanded, thus demonstrating the affinity between SD and SPC. The incorporation of SD caused SPC liposomes to have a decreased diameter according to light scattering experiments. When SPC liposomes were injected into an aqueous subphase, their destruction yielding surface-active monomers could be monitored by changes in surface pressure. SD-loaded liposomes displayed a much faster kinetics when the surface density of surface-active monomers was plotted against time, with rate constants increasing significantly with the SD concentration. The kinetic profile can be quantitatively analyzed by plotting ln[1 - (gamma/gamma infinity)] versus t1/2.
authors.affiliation: Faculdade de Ciências Farmacêuticas, Pesquisador recém-doutor do CNPq, Programa de Pós-graduação em Ciências Farmacêuticas, Unesp, Araraquara, SP, Brazil.
authors.forename: S M B
authors.initials: SM
authors.lastname: Souza
authors.forename: O N
authors.initials: ON
authors.lastname: Oliveira
authors.forename: M V
authors.initials: MV
authors.lastname: Scarpa
authors.forename: A G
authors.initials: AG
authors.lastname: Oliveira
mesh_terms: D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000378:metabolism*; D004008:Diclofenac / Q000378:metabolism*; D007700:Kinetics; D008027:Light; D008081:Liposomes / Q000378:metabolism*; D010713:Phosphatidylcholines / Q000378:metabolism; D010743:Phospholipids / Q000378:metabolism*; D012542:Scattering, Radiation; D013025:Glycine max / Q000737:chemistry; D013499:Surface Properties; D013500:Surface Tension; D014867:Water / Q000737:chemistry
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D008081:Liposomes; D010713:Phosphatidylcholines; D010743:Phospholipids; D014867:Water; D004008:Diclofenac