title: Formation of fluorinated nonionic surfactant microemulsions in hydrofluorocarbon 134a (HFC 134a).
abstract: A structurally related series of fluorinated nonionic oxyethylene glycol surfactants of the type C(m)F(2m+1)(CH(2))(n)O[(CH(2)CH(2)O)(p)H], denoted C(m.n)E(p) (where m=4, 6, or 7, m=1 or 2, and p=4 or 6) were synthesized and their surface behavior in aqueous solution was characterized. The ability of these surfactants to form water-in-hydrofluorocarbon (HFC) propellant 134a microemulsions suitable for use in the aerosolized delivery of water-soluble drugs has been investigated. Phase studies showed that, regardless of the composition used, clear one-phase systems could not be prepared if a fluorinated nonionic surfactant was used alone, or in combination with a short or medium fluorocarbon alcohol cosurfactant. Clear one-phase systems could, however, be prepared if a short-chain hydrocarbon alcohol, such as ethanol, n-propanol, or n-pentanol, was used as cosurfactant, with the extent of the one-phase region increasing with decreased chain length of the alcohol cosurfactant. Light-scattering studies on a number of the hydrocarbon-alcoholcontaining systems in the propellant-rich part of the phase diagram showed that only systems prepared with C(4.2)E(6) and propanol contained microemulsion droplets (all other systems investigated were considered to be cosolvent systems).
authors.affiliation: Department of Pharmacy, King's College London, The 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