Self-Assembled Structure of α-Isostearyl Glyceryl Ether Affects Skin Permeability-a Lamellar with 70-nm Spaces and L3 Phase Enhanced the Transdermal Delivery of a Hydrophilic Model Drug.

Self-assembled surfactant structures, such as liquid crystals, have the potential to enhance transdermal drug delivery. In the present study, the pseudo-ternary system of GET (composed of α-Isostearyl glyceryl ether (GEIS) and polysorbate 60)/1,3 butanediol (BG)/water) was shown to exhibit a complex phase diagram. Small- and wide-angle X-ray scattering (SWAXS) and freeze-fracture transmission electron microscopy (FF-TEM) revealed that GET6BG60 (6%GET/60%BG/34%Water) formed a lamellar phase with a repeated distance of approximately 72 nm. Such a long-repeated distance of the lamellar phase was unique in the surfactant system. Moreover, the various structures, such as multilamellar vesicles and branched-like layers, were observed, which suggested that they might be deformable. On the other hand, only core-shell particles were observed in GET6BG20, the core of which was an L3 phase. GET6BG20 and GET6BG60 significantly enhanced the skin permeation of the hydrophilic model drug, antipyrine (ANP) (log Ko/w, - 1.51). However, their permeation profiles were distinct. Liquid chromatography-tandem mass spectrometry revealed that epidermal accumulation of GEIS was significantly higher with GET6BG60 than GET6BG20 after 1.5 h of permeation, which might be attributed to differences in their deformable properties. Furthermore, GEIS was reported to affect intercellular lipids. Accumulated GEIS in the epidermis may have interacted with intercellular lipids and enhanced the transdermal delivery of ANP. The difference in the permeation profiles of ANP may be attributed to the penetration process of GEIS in the epidermis. This study suggests that GET6BG20 and GET6BG60 are unique carriers to enhance the permeation of hydrophilic drugs, such as ANP.

Efficacy of Pseudo-Ceramide-Containing Steroid Lamellar Cream in Patients with Mild to Moderate Atopic Dermatitis: A Randomized, Double-Blind Study.

INTRODUCTION: Atopic dermatitis (AD) is a chronic inflammatory skin disorder involving decreased barrier function of the stratum corneum. This decrease, caused by a reduction in ceramide, the primary component of intercellular lipids in the stratum corneum, leads to a disturbance in the lamellar structure. METHODS: We developed a formulation (test cream) containing a steroid and synthetic pseudo-ceramide (SLE: N-(3-hexadecyloxy-2-hydroxypropyl)-N-2-hydroxyethyl hexadecanamide) that forms a lamellar structure on the skin after its application and drying. The formulation or control cream (a formulation containing a steroid but not pseudo-ceramide that does not form a lamellar structure) was applied twice daily for 2 weeks to the lesional area of 34 participants with mild to moderate AD symptoms. RESULTS: The test cream showed a periodic structure with an interface space of approximately 8.2 nm in transmission electron microscopy and small- and wide-angle X-ray scattering, similar to the lamellar structure in the human stratum corneum. In the double-blind test, the anti-inflammatory effects of the test cream (n = 17) were comparable to those of the control cream (n = 17). In the test cream group, a significant increase in the stratum corneum moisture content (p < 0.01) and significant decrease in transepidermal water loss (p < 0.05) were observed at weeks 1 and 2 after application compared with those before application. No such change was observed in the control group. CONCLUSION: The results indicate that, even with a relatively short application period of 2 weeks, the test cream not only suppressed inflammation of the lesional area, but also improved the inherent barrier function of the stratum corneum, suggesting its potential as a treatment option for patients with AD.

Efficacy of Heparinoid Cream Containing Pseudo-Ceramide for Remission of Atopic Dermatitis.

PURPOSE: Atopic dermatitis (AD) is characterized by chronic inflammation, which frequently recurs, is exacerbated, and enters remission. A maintenance remission period is important for AD patients. We developed a formulation for use during AD remission, containing heparinoid and pseudo-ceramide that forms a lamellar structure. We evaluated the allergen permeability and examined the formulation's efficacy in maintaining remission in patients with AD. MATERIALS AND METHODS: Seventeen AD patients applied a cream containing 0.3% heparinoid and pseudo-ceramide (test cream group, n = 10), or a general cream containing 0.3% heparinoid (control cream group, n = 7) to their arm for four weeks after inducing remission with the application of a steroid cream for two weeks. RESULTS: The lamellar structure of the test cream was confirmed with small- and wide-angle x-ray scattering analysis and observation by transmission electron microscopy. The test cream inhibited the penetration of V8 protease significantly compared to the control cream in vitro. According to AD severity score by dermatologists, the effects remission maintenance of the test cream group were comparable to those of the control cream group. However, the test cream group had a significantly increased skin hydration value compared to the control cream group. A significant decrease in transepidermal water loss, an indicator of skin barrier function, was shown in the test cream group compared to the control cream group. CONCLUSION: The cream with lamellar structures containing heparinoid and pseudo-ceramides may inhibit allergen penetration. Moreover, skin properties improved during the remission period; thus, the formulation we developed was suitable for use during the AD remission period.

Structure and rheology of a self-standing nanoemulsion.

A stable nanoemulsion consisting of nanometer-sized oil droplets in water having a self-standing capability was prepared by high-pressure emulsification. The nanoemulsion does not flow and has a yield stress. This nonfluidity is ascribed to the crystal-like lattice structure of nanodroplets. The lattice structure was observed by transmission electron microscopy of a freeze-fractured surface of the specimen. Small-angle neutron scattering (SANS) revealed the presence of an ordered structure in addition to spherical domains with a radius of 17 nm. This long-range order is, in principle, due to electrostatic repulsive interaction between charged nanodroplets. Dynamic light scattering (DLS) showed two relaxation modes, one for the collective motion of the lattice and the other for the translational diffusion of the nanodroplets. Dilution of the nanoemulsion resulted in a transition from a crystal-like structure to a typical colloidal solution.

Long-term alteration in the expression of keratins 6 and 16 in the epidermis of mice after chronic UVB exposure.

The influences of chronic UVB exposure on epidermal differentiation have been poorly studied compared to dermal photo-aging although those effects are very important in terms of photo-damage to the skin. The purpose of this study was to investigate the effects of chronic UVB exposure on keratin expression in the epidermis. The effects on murine skin of chronic exposure to weak UVB (below 1 MED) was examined by immunoblotting for keratins K10, K5, K6, and K16, by immunohistochemistry using antibodies to K6, K16, and Ki67 as well as by conventional HE staining of skin sections. Alterations of keratin expression induced by the chronic UVB exposure were distinct from those elicited by a single acute UVB exposure. The expression of keratins K6 and K16 was quite long-lasting, continuing for 7 weeks after 6 weeks of chronic UVB exposure and for 6 weeks after 9 weeks of chronic UVB exposure. In contrast, K6 and K16 expression induced by a single UVB exposure at 0.5 MED or 3 MED almost ceased within 2 weeks after that exposure. Furthermore, the expression of the constructive keratins, K5 and K10, remained almost unchanged by chronic UVB exposure. Epidermal thickness was increased significantly immediately after the 9 weeks of chronic UVB exposure; however, it had returned to normal level 6 weeks later. The alterations in keratin expression accompanied the marked disruption of the ordered ultrastructure of keratin intermediate filaments, which were observed by TEM. Thus, chronic exposure to UVB has a deep impact on the biosynthetic regulation of different keratins in the epidermis, thereby interfering with the ordered ultrastructure of keratin intermediate filaments. Those events could have relevance to the mechanism of photo-damage, such as fine wrinkles observed in chronically UV-exposed skin in addition to dermal photo-aging.

In situ small-angle neutron scattering and rheological measurements of shear-induced gelation.

The microscopic structure of shear-induced gels for a mixed solution of 2-hydroxyethyl cellulose and nanometer-size spherical droplets has been investigated by in situ small-angle neutron scattering (SANS) with a Couette geometry as a function of shear rate gamma. With increasing gamma, the viscosity increased rapidly at gamma approximately 4.0 s(-1), followed by a shear thinning. After cessation of shear, the system exhibited an extraordinarily large steady viscosity. This phenomenon was observed as a shear-induced sol-gel transition. Real-time SANS measurements showed an increase in the scattering intensity exclusively at low scattering angle region. However, neither orientation of polymer chains nor droplet deformation was detected and the SANS patterns remained isotropic irrespective of gamma. It took about a few days for the gel to recover its original sol state. A possible mechanism of gelation is proposed from the viewpoint of shear-induced percolation transition.

The formation of wrinkles caused by transition of keratin intermediate filaments after repetitive UVB exposure.

It has been reported that the formation of wrinkles involves changes in the elastic properties of the dermis due to the denaturation of elastic fibers. Several studies have shown that the hydration condition of the stratum corneum is also important in wrinkle formation. It is, however, still unclear how the stratum corneum contributes to wrinkle formation. Here we investigated the relationship between the formation of wrinkles and changes in the physical properties and condition of the skin after repetitive ultraviolet B (UVB) irradiation of hairless mice (HR/ICR). Repetitive UVB irradiation caused wrinkles on the dorsal skin of the mice. The elasticity (E') of the stratum corneum of UVB-irradiated mice was significantly lower than that of age-matched control (unirradiated) mice. UVB exposure also caused a deterioration of the fibrous ultrastructure of keratin intermediate filaments (KIFs) in the skin. We conclude that the deterioration of KIFs in the stratum corneum caused by repetitive UVB irradiation decreases the elastic properties of the stratum corneum, resulting in the formation of wrinkles.