title: Formulation and evaluation of release and swelling mechanism of a water-in-oil emulsion using factorial design.
abstract: Water-in-oil emulsions have a potential as a parenteral prolonged release system for hydrophilic drugs. A consistent challenge when developing an emulsion drug delivery system is to obtain a proper release characteristic of the entrapped drug. The aim of the present study was to study the release mechanism from water-in-oil emulsions. Secondly, to study the effects of droplet size, phase ratio and osmotic pressure on the release rate of glucose from water-in-oil emulsions in a factorial experimental design. The release mechanism of glucose was deduced from the release kinetics of two coentrapped marker molecules, glucose and inulin, with a molecule weight of 180 and 5000 g/mol, respectively. The results indicate that release of glucose was dominated by diffusion through the oily barrier as opposed to membrane rupture. Using statistical methodology, the release rate of glucose could be varied 8 fold in a controlled manner with osmotic pressure as the most important parameter. The osmotic behaviour of the emulsions was further studied in a dynamic swelling study. These results show that the release of entrapped hydrophilic drug can be controlled within certain limits using pharmaceutical formulation principles.
authors.affiliation: Department of Pharmaceutics, The Royal Danish School of Pharmacy, Universitetsparken 2, DK-2100, Copenhagen O, Denmark.
authors.forename: S
authors.initials: S
authors.lastname: Bjerregaard
authors.forename: I
authors.initials: I
authors.lastname: Söderberg
authors.forename: C
authors.initials: C
authors.lastname: Vermehren
authors.forename: S
authors.initials: S
authors.lastname: Frokjaer
mesh_terms: D003692:Delayed-Action Preparations / Q000493:pharmacokinetics*; D004058:Diffusion; D016503:Drug Delivery Systems / Q000379:methods*; D004655:Emulsions / Q000493:pharmacokinetics*; D005947:Glucose / Q000493:pharmacokinetics*; D007444:Inulin / Q000493:pharmacokinetics*; D009997:Osmotic Pressure; D010316:Particle Size; D012044:Regression Analysis; D012995:Solubility; D013997:Time Factors
chemical_list: D003692:Delayed-Action Preparations; D004655:Emulsions; D007444:Inulin; D005947:Glucose