title: Nanostructured lipid carriers versus microemulsions for delivery of the poorly water-soluble drug luteolin.
abstract: OBJECTIVE
  Nanostructured lipid carriers and microemulsions effectively deliver poorly water-soluble drugs. However, few studies have investigated their ability and difference in improving drug bioavailability, especially the factors contributed to the difference. Thus, this study was aimed at investigating their efficiency in bioavailability enhancement based on studying two key processes that occur in NLC and ME during traverse along the intestinal tract: the solubilization process and the intestinal permeability process.
  
  
  METHODS
  The nanostructured lipid carriers and microemulsions had the same composition except that the former were prepared with solid lipids and the latter with liquid lipids; both were evaluated for particle size and zeta potential. Transmission electron microscopy, differential scanning calorimetry, and X-ray diffraction were performed to characterize their properties. Furthermore, in vitro drug release, in situ intestinal absorption, and in vitro lipolysis were studied. The bioavailability of luteolin delivered using nanostructured lipid carriers in rats was compared with that delivered using microemulsions and suspensions.
  
  
  RESULTS
  The in vitro analysis revealed different release mechanisms for luteolin in nanostructured lipid carriers and microemulsions, although the in situ intestinal absorption was similar. The in vitro lipolysis data indicated that digestion speed and extent were higher for microemulsions than for nanostructured lipid carriers, and that more of the former partitioned to the aqueous phase. The in vivo bioavailability analysis in rats indicated that the oral absorption and bioavailability of luteolin delivered using nanostructured lipid carriers and microemulsions were higher than those of luteolin suspensions.
  
  
  CONCLUSIONS
  Nanostructured lipid carriers and microemulsions improved luteolin's oral bioavailability in rats. The rapid lipid digestion and much more drug solubilized available for absorption in microemulsions may contribute to better absorption and higher bioavailability.
authors.affiliation: School of Pharmacy, Shanghai University of Traditional Chinese Medicine, Shanghai 201203, China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Liu
authors.affiliation: School of Pharmacy, Shanghai University of Traditional Chinese Medicine, Shanghai 201203, China.
authors.forename: Lan
authors.initials: L
authors.lastname: Wang
authors.affiliation: School of Pharmacy, Shanghai University of Traditional Chinese Medicine, Shanghai 201203, China.
authors.forename: Yiqing
authors.initials: Y
authors.lastname: Zhao
authors.affiliation: School of Pharmacy, Shanghai University of Traditional Chinese Medicine, Shanghai 201203, China.
authors.forename: Man
authors.initials: M
authors.lastname: He
authors.affiliation: School of Pharmacy, Shanghai University of Traditional Chinese Medicine, Shanghai 201203, China.
authors.forename: Xin
authors.initials: X
authors.lastname: Zhang
authors.affiliation: School of Pharmacy, Shanghai University of Traditional Chinese Medicine, Shanghai 201203, China.
authors.forename: Mengmeng
authors.initials: M
authors.lastname: Niu
authors.affiliation: School of Pharmacy, Shanghai University of Traditional Chinese Medicine, Shanghai 201203, China. Electronic address: npfeng@hotmail.com.
authors.forename: Nianping
authors.initials: N
authors.lastname: Feng
mesh_terms: D000284:Administration, Oral; D000818:Animals; D001682:Biological Availability; D002152:Calorimetry, Differential Scanning; D004337:Drug Carriers / Q000737:chemistry; D016503:Drug Delivery Systems; D004655:Emulsions; D007408:Intestinal Absorption; D008055:Lipids / Q000737:chemistry*; D047311:Luteolin / Q000008:administration & dosage* / Q000737:chemistry / Q000493:pharmacokinetics; D008297:Male; D046529:Microscopy, Electron, Transmission; D049329:Nanostructures; D010316:Particle Size; D051381:Rats; D017207:Rats, Sprague-Dawley; D012995:Solubility; D014867:Water / Q000737:chemistry; D014961:X-Ray Diffraction
chemical_list: D004337:Drug Carriers; D004655:Emulsions; D008055:Lipids; D014867:Water; D047311:Luteolin
keywords: In situ intestinal absorption; In vitro lipolysis; Luteolin; Microemulsions; Nanostructured lipids carriers; Oral bioavailability