title: pH compartmented w/o/w multiple emulsion: a diffusion study.
abstract: In order to develop w/o/w emulsions characterized by two separate aqueous phases of different pH, a preliminary study was carried out to obtain a better insight into the possible diffusion processes taking place between an inner acidic aqueous phase and an external phase of higher pH (pH approximately 6). In fact, such systems could be of great interest for pharmaceutical use. For this purpose, a model emulsion was formulated. The study of pH and conductivity showed that acidic species transport take place between the two aqueous compartments. The three main release mechanisms that might be responsible for this passage across the oil phase were investigated: breakdown of oil globules, facilitated transport by surfactant micelles across the oil phase or by Fickian diffusion. It appears that this last mechanism was involved. In order to control this diffusion process, an alkaline species, octadecylamine was introduced in the oil phase. This compound could form an ion pair with the lactate ion at the interface of the external aqueous phase and the oil phase, thus, limiting the acidification of the external aqueous phase.
authors.affiliation: Laboratoire de Physico-Chimie, Pharmacotechnie et Biopharmacie UMR CNRS 8612, Centre d'Etudes Pharmaceutiques, 5 rue J.B Clément, 92296 Châtenay-Malabry, France.
authors.forename: G M
authors.initials: GM
authors.lastname: Tedajo
authors.forename: M
authors.initials: M
authors.lastname: Seiller
authors.forename: P
authors.initials: P
authors.lastname: Prognon
authors.forename: J L
authors.initials: JL
authors.lastname: Grossiord
mesh_terms: D000465:Algorithms; D002138:Calibration; D004058:Diffusion; D004339:Drug Compounding; D004553:Electric Conductivity; D004655:Emulsions / Q000737:chemistry*; D006851:Hydrochloric Acid / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D019344:Lactic Acid / Q000737:chemistry; D008278:Magnesium Sulfate / Q000737:chemistry; D009821:Oils; D012212:Rheology; D014867:Water
chemical_list: D004655:Emulsions; D009821:Oils; D014867:Water; D019344:Lactic Acid; D008278:Magnesium Sulfate; D006851:Hydrochloric Acid