title: A study on the solid state characteristics of spray-congealed glyceryl dibehenate solid lipid microparticles containing ibuprofen.
abstract: OBJECTIVE
  To study the solid state modifications of ibuprofen (IBU)-loaded spray-congealed glyceryl dibehenate (GB) solid lipid microparticles (SLMs) and the influence of polymeric additives using a combination of calorimetric and spectroscopic techniques.
  
  
  METHODS
  IBU-loaded SLMs were produced by spray congealing with GB as the matrix material. Polyvinyl-2-pyrrolidone-vinyl-acetate (PVP/VA) and ethylcellulose (EC) were employed as additives. Of particular interest in this study were the solid state modifications of the drug and GB matrix induced by spray congealing and the effects of aging, as well as drug-matrix interactions. Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy, differential scanning calorimetry, hot stage microscopy and powder X-ray diffraction provided complementary analyses in understanding drug and lipid matrix polymorphism and interaction. The yield, morphology, drug content and encapsulation efficiencies of SLMs were also investigated.
  
  
  CONCLUSIONS
  Drug encapsulation efficiencies and yields of spray congealed SLMs were consistently high for all formulations. GB congealed as an unstable α-polymorph which reverted to the stable β'-polymorph within a few weeks. PVP/VA accelerated the polymorphic conversion in less than a week, while EC took about a year. IBU formed a solid solution with GB regardless of the GB polymorphic form.
  
  
  CONCLUSIONS
  Spray congealing is efficient for producing drug-loaded SLMs. It induces polymorphic changes in GB. The latter incorporated 20%, w/w IBU as a solid solution and polymeric additives exerted contrasting effects on the GB polymorphic conversion.
authors.affiliation: a GEA-NUS Pharmaceutical Processing Research Laboratory, Department of Pharmacy, National University of Singapore , Singapore.
authors.forename: Priscilla Chui Hong
authors.initials: PC
authors.lastname: Wong
authors.affiliation: a GEA-NUS Pharmaceutical Processing Research Laboratory, Department of Pharmacy, National University of Singapore , Singapore.
authors.forename: Paul Wan Sia
authors.initials: PW
authors.lastname: Heng
authors.affiliation: a GEA-NUS Pharmaceutical Processing Research Laboratory, Department of Pharmacy, National University of Singapore , Singapore.
authors.forename: Lai Wah
authors.initials: LW
authors.lastname: Chan
mesh_terms: D002626:Chemistry, Pharmaceutical / Q000379:methods*; D005227:Fatty Acids / Q000032:analysis / Q000737:chemistry*; D007052:Ibuprofen / Q000032:analysis / Q000737:chemistry*; D008055:Lipids / Q000032:analysis / Q000737:chemistry*; D008863:Microspheres; D010316:Particle Size; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods; D014961:X-Ray Diffraction / Q000379:methods
chemical_list: D005227:Fatty Acids; D008055:Lipids; C086409:glyceryl behenate; D007052:Ibuprofen
keywords: Differential scanning calorimetry; X-ray diffraction; polymers; polymorphism; spray congealing; sustained release