title: A topical w/o/w multiple emulsions prepared with Tetronic 908 as a hydrophilic surfactant: formulation, characterization and release study.
abstract: OBJECTIVE
  The aim of this work was to prepare the stable water/oil/water multiple emulsions (MEs), to investigate the usage of poloxamine 908, to observe the influence of surfactant percentage on the properties of MEs.
  
  
  METHODS
  MEs were prepared by liquid paraffin, cetyl dimethicone copolyol and poloxamine 908 by a two-step emulsification procedure. Caffeine was used as a water-soluble model. The viscosity, conductivity and globule size of MEs were followed over time.
  
  
  RESULTS
  The formulations containing 1% cetyl dimethicone copolyol and 1 or 2% poloxamine 908 were the most stable systems. The globule size of MEs ranged from 20 to 37 microm and did not change during time. The yield of MEs was between 99.6% and 98.7%. The conductivity increased and the viscosity of systems decreased during time. Increase in poloxamine 908 influenced the viscosity of the system, with the viscosity decreasing as the hydrophilic surfactant concentrations were increased. Caffeine release from the MEs was slow; the release was affected by both surfactant concentrations.
  
  
  CONCLUSIONS
  Poloxamine 908 could be used as a hydrophilic surfactant for formulation of w/o/w MEs. The concentration of poloxamine 908 was a very important parameter in preparing stable MEs. It was concluded that caffeine might be transported out by molecular diffusion and through a reverse micellar mechanism controlled by the viscosity of the system.
authors.affiliation: Department of Pharmaceutical Technology, Gazi University Faculty of Pharmacy, Etiler-06330, Ankara, Turkey. feegosh@yahoo.com
authors.forename: Figen
authors.initials: F
authors.lastname: Tirnaksiz
authors.forename: Ozlem
authors.initials: O
authors.lastname: Kalsin
mesh_terms: D000287:Administration, Topical; D002626:Chemistry, Pharmaceutical; D004655:Emulsions; D009821:Oils / Q000008:administration & dosage / Q000138:chemical synthesis / Q000493:pharmacokinetics; D011092:Polyethylene Glycols / Q000008:administration & dosage / Q000138:chemical synthesis* / Q000493:pharmacokinetics*; D011409:Propylene Glycols / Q000008:administration & dosage / Q000138:chemical synthesis* / Q000493:pharmacokinetics*; D013501:Surface-Active Agents / Q000008:administration & dosage / Q000138:chemical synthesis* / Q000493:pharmacokinetics*; D014783:Viscosity; D014867:Water / Q000737:chemistry
chemical_list: D004655:Emulsions; D009821:Oils; C116176:PEO-PPO-PEO; D011409:Propylene Glycols; D013501:Surface-Active Agents; D014867:Water; D011092:Polyethylene Glycols