title: Fluorinated ionic surfactant microemulsions in hydrofluorocarbon 134a (HFC 134a).
abstract: The factors influencing the formation of water-in-134a-propellant microemulsions using the fluorinated ionic surfactants ammonium perfluorooctanoate, ammonium perfluoroheptanoate, and sodium perfluorooctanoate has been determined. None of the fluorinated ionic surfactants could be used to prepare clear, one-phase systems when used as sole surfactant, but they could be when combined with a short-chain fluoro- or hydrocarbon alcohol in surfactant:cosurfactant weight-mixing ratios (K(m)) in the range 1:2 to 2:1. When hydrocarbon alcohols were used this clear region extended over a wide range of compositions and was confirmed by means of photon correlation spectroscopy (PCS) to contain microemulsion droplets in the propellant-rich part of the phase diagram. PCS studies performed in the presence of the water-soluble drug terbutaline sulfate showed that it was possible to solubilize the drug within water-in-propellant microemulsion droplets. These studies confirm for the first time that it is possible to prepare water-in-propellant 134a microemulsions using fluorinated ionic surfactants and to solubilize water-soluble drugs within these systems.
authors.affiliation: Department of Pharmacy, King's College London, Franklin-Wilkins Building, 150 Stamford Street, SE1 9NN, London, United Kingdom.
authors.forename: Nilesh
authors.initials: N
authors.lastname: Patel
authors.forename: Maria
authors.initials: M
authors.lastname: Marlow
authors.forename: M Jayne
authors.initials: MJ
authors.lastname: Lawrence
mesh_terms: D016503:Drug Delivery Systems / Q000379:methods; D004655:Emulsions; D006845:Hydrocarbons, Fluorinated / Q000737:chemistry*; D013501:Surface-Active Agents / Q000737:chemistry*
chemical_list: D004655:Emulsions; D006845:Hydrocarbons, Fluorinated; D013501:Surface-Active Agents