Liquid crystalline nanoparticles (LCNs) were prepared using glyceryl monooleyl ether (GME) by the modified film rehydration method. Hydrogenated lecithin (HL), 1,3-butylene glycol (1,3-BG), and Poloxamer 407 were used as additives. The prepared LCN formulations were evaluated based on particle size, smallangle X-ray diffraction (SAXS) analysis, 1 H-and
19F-NMR spectra, and in vitro skin permeation across Yucatan micropig skin. The composition (weight percent) of the LCN formulations were GME-HL-1,3-BG (4 : 1 : 15), 4% GME-based LCN and GME-HL-1,3-BG (8 : 1 : 15), 8% GME-based LCN and their mean particle sizes were 130-175 nm. Flurbiprofen 5 and 10 mg was loaded into 4% GME-based LCN and 8% GMEbased LCN systems, respectively. The results of SAXS and NMR suggested that both flurbiprofen-loaded formulations consist of particles with reverse type hexagonal phase (formation of hexosome) and flurbiprofen molecules were localized in the lipid domain through interaction of flurbiprofen with the lipid components. Flurbiprofen transport from the LCN systems across the Yucatan micropig skin was increased compared to flurbiprofen in citric buffer (pH 3.0). The 8% GME-based LCN systems was superior to the 4% GME-based LCN for flurbiprofen transport. Since the internal hexagonal phase in the 8% GME-based LCN systems had a higher degree of order compared to the 4% GME-based LCN in SAXS patterns, the 8% GME-based LCN system had a larger surface area, which might influence flurbiprofen permeation. These results indicated that the GME-based LCN system is effective in improving the skin permeation of flurbiprofen across the skin.Key words lyotropic liquid crystal; liquid crystalline nanoparticle; hexosome; skin permeation; flurbiprofen; NMR Under some circumstances, transdermal delivery may be superior to other routes of delivery due to advantages such as avoidance of first pass elimination and a lack of invasiveness. However, relatively few transdermal drugs have been commercialized owing to the efficient barrier function of the stratum corneum, which is located on the outer layer of the skin. To overcome the barrier function of the stratum corneum, several physical and chemical methods have been developed.
1)Recently, lyotropic liquid crystal (LLC) systems have been developed as a chemical method to overcome the stratum corneum barrier.2,3) LLCs are usually composed of amphiphilic molecules and solvents that can form a variety of structures, including lamellar (L α ), hexagonal (normal, or reverse) and inverted cubic (bicontinuous and micellar) structures. 4) Among these LLC systems, some of liquid crystal structures form a liquid crystalline nanoparticles (LCNs) by dispersing in an aqueous environment and the LCNs of reverse hexagonal phase and bicontinuous cubic phase are called "hexosomes (H II )" and "cubosomes," respectively. 3,5) Glycerol monoolate (GMO) has been widely studied as an additive to form LLCs and their LCNs.6,7) Effect of the additives such as block copolymer formation and electrostatic interaction were also i...