title: Preparation and characterization of dexamethasone microemulsion based on pseudoternary phase diagram.
abstract: BACKGROUND
  The increased incidence of inflammatory diseases has necessitated the need to search for new topical dosage form of dexamethasone.
  
  
  OBJECTIVE
  The purpose of the present study was the preparation and evaluation of novel microemulsion as a topical delivery system for dexamethasone by mixing appropriate amount of surfactant including Tween 80 and Labrasol, cosurfactant such as capryol 90 and oil phase including labrafac lipophile wl-transcutol P (10:1 ratio).
  
  
  METHODS
  The prepared microemulsions were evaluated regarding their particle size, zeta potential, X-Ray scattering, conductivity, stability, viscosity, differential scanning calorimetry (DSC), scanning electron microscopy (SEM), refractory index (RI), pH, and x-ray diffraction (XRD).
  
  
  RESULTS
  The results showed that the maximum oil was incorporated in microemulsion system that contained surfactant to cosurfactant ratio of 4:1. The mean droplet size range of microemulsion formulation was in the range of 5.09 to 159 nm, and its refractory index (RI) and pH were 1.44 and 7, respectively. Viscosity range was 57-226 cps. Drug release profile showed that 48.18% of the drug released in the 24 hours of experiment. Also, Hexagonal, cubic and lamellar structures were seen in the SEM photograph and XRD peak of microemulsions.
  
  
  CONCLUSIONS
  This study demonstrated that physicochemical properties and in vitro release were dependent upon the contents of S/C, water, and oil percentage in formulations. SAXS technique and SEM obtained important information about microstructure of microemulsions. W/O and bicontinuous microemulsion with different microstructures were found in formulations.
authors.affiliation: Nanotechnology Research Center, Jundishapur University of Medical Sciences, Ahvaz, IR Iran ; Department of Pharmaceutics, Faculty of Pharmacy, Jundishapur University of Medical Sciences, Ahvaz, IR Iran.
authors.forename: Eskandar
authors.initials: E
authors.lastname: Moghimipour
authors.affiliation: Nanotechnology Research Center, Jundishapur University of Medical Sciences, Ahvaz, IR Iran ; Department of Pharmaceutics, Faculty of Pharmacy, Jundishapur University of Medical Sciences, Ahvaz, IR Iran.
authors.forename: Anayatollah
authors.initials: A
authors.lastname: Salimi
authors.affiliation: Department of Pharmaceutics, Faculty of Pharmacy, Jundishapur University of Medical Sciences, Ahvaz, IR Iran.
authors.forename: Masoud
authors.initials: M
authors.lastname: Karami
authors.affiliation: Department of Pharmaceutics, Faculty of Pharmacy, Jundishapur University of Medical Sciences, Ahvaz, IR Iran.
authors.forename: Sara
authors.initials: S
authors.lastname: Isazadeh
keywords: Calorimetry, Differential Scanning; Dexamethasone; Emulsion