An adequate hydration level is essential to maintain epidermal barrier functions and normal physiological activities of skin tissues. Diverse moisturizing agents and pharmaceutical formulations for dermal deliveries have thus extensively been investigated. This review comprehensively discusses scientific outcomes of moisturizing agents and pharmaceutical vehicles for skin moisturization, thereby providing insight into designing innovative pharmaceutical formulations for effective skin moisturization. Areas covered: We discussed the functions of various moisturizing agents ranging from conventional creams to novel moisturizers which has recently been explored. In addition, novel pharmaceutical formulations for efficient dermal delivery of the moisturizers, in particular, nanocarriers, were discussed along with their uses in commercial products. Expert opinion: Although various moisturizing agents have demonstrated their promising effects, exploitation of pharmaceutical formulations for their dermal delivery have been limited to few commonly used moisturizing agents. Thus, combinatorial investigation of novel moisturizers and pharmaceutical vehicles should be further conducted. As a new concept for improving skin moisturization, skin regeneration technologies using therapeutic cells have recently shown great promise for skin moisturization, but major challenges remain, such as efficient delivery and prolonged survival of such cells. Thus, novel approaches for improving skin moisturization require continuous efforts of pharmaceutical scientists to address the remaining problems.

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In this study, the effect of particle size of genistein-loaded solid lipid particulate systems on drug dissolution behavior and oral bioavailability was investigated. Genistein-loaded solid lipid microparticles and nanoparticles were prepared with glyceryl palmitostearate. Except for the particle size, other properties of genistein-loaded solid lipid microparticles and nanoparticles such as particle composition and drug loading efficiency and amount were similarly controlled to mainly evaluate the effect of different particle sizes of the solid lipid particulate systems on drug dissolution behavior and oral bioavailability. The results showed that genistein-loaded solid lipid microparticles and nanoparticles exhibited a considerably increased drug dissolution rate compared to that of genistein bulk powder and suspension. The microparticles gradually released genistein as a function of time while the nanoparticles exhibited a biphasic drug release pattern, showing an initial burst drug release, followed by a sustained release. The oral bioavailability of genistein loaded in solid lipid microparticles and nanoparticles in rats was also significantly enhanced compared to that in bulk powders and the suspension. However, the bioavailability from the microparticles increased more than that from the nanoparticles mainly because the rapid drug dissolution rate and rapid absorption of genistein because of the large surface area of the genistein-solid lipid nanoparticles cleared the drug to a greater extent than the genistein-solid lipid microparticles did. Therefore, the findings of this study suggest that controlling the particle size of solid-lipid particulate systems at a micro-scale would be a promising strategy to increase the oral bioavailability of genistein.

We investigated the combined moisturizing effect of liposomal serine and a cosmeceutical base selected in this study. Serine is a major amino acid consisting of natural moisturizing factors and keratin, and the hydroxyl group of serine can actively interact with water molecules. Therefore, we hypothesized that serine efficiently delivered to the stratum corneum (SC) of the skin would enhance the moisturizing capability of the skin. We prepared four different cosmeceutical bases (hydrogel, oil-in-water (O/W) essence, O/W cream, and water-in-oil (W/O) cream); their moisturizing abilities were then assessed using a Corneometer®. The hydrogel was selected as the optimum base for skin moisturization based on the area under the moisture content change-time curves (AUMCC) values used as a parameter for the water hold capacity of the skin. Liposomal serine prepared by a reverse-phase evaporation method was then incorporated in the hydrogel. The liposomal serine-incorporated hydrogel (serine level=1%) showed an approximately 1.62~1.77 times greater moisturizing effect on the skin than those of hydrogel, hydrogel with serine (1%), and hydrogel with blank liposome. However, the AUMCC values were not dependent on the level of serine in liposomal serine-loaded hydrogels. Together, the delivery of serine to the SC of the skin is a promising strategy for moisturizing the skin. This study is expected to be an important step in developing highly effective moisturizing cosmeceutical products.

The study aimed to assess the skin hydrating effect of hydrogels containing serine‐loaded solid lipid nanoparticles (SLN) prepared with lipids having high affinity to the stratum corneum (SC) and polysaccharide‐rich reed (Phragmites communis) root extract (RRE). To select a lipid with high affinity to the SC, the interaction between the SC obtained by a tape stripping technique and three different lipids such as glycerol mono‐oleate (GMO), lauric acid (LA), and capric acid (CA) was examined by ATR‐FTIR. After choosing GMO as the lipid with the highest affinity to the SC, hydrogel formulations containing serine‐loaded GMO SLN and/or RRE were prepared, and their skin hydrating effect was evaluated after applying the hydrogels to the surface of human skin. The hydrogel containing serine‐loaded GMO SLN and RRE exhibited the greatest skin moisturizing effect, followed by the hydrogels with serine‐loaded GMO SLN, RRE, and blank hydrogel. The results implied that SLN prepared with GMO having high affinity to the SC could be used as an efficacious carrier of serine for the purpose of skin hydration, and synergistic skin hydrating effect could be achieved by different skin moisturizing mechanisms of the serine‐loaded SLN and RRE.

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Celecoxib is a non-steroidal, anti-inflammatory drug used in the treatment of pain and inflammation associated with rheumatoid arthritis, and several other inflammatory disorders. It is a class II compound according to the Biopharmaceutics Classification System owing to its low water solubility and high membrane permeability. The objective of this study was to improve the solubility and dissolution rate of celecoxib using solid surfactant technology that might be useful in developing solid dosage forms. Solid surfactant was developed by mixing and grinding together a liquid surfactant (Tween 80) with various inorganic carriers like Fujicalin Ò (Dibasic Calcium Phosphate Anhydrous), Pineflow Ò (Porous-structured Maltodextrin), Neusilin Ò (Magnesium Alumino metasilicate) and Aerosil Ò (Colloidal Silicon dioxide) in a mortar and pestle in different ratios of liquid surfactant and the carrier to obtain solid surfactants. The celecoxib tablets prepared with solid surfactants were then evaluated for their solubility and dissolution properties. Among the fillers used, Fujicalin showed the highest solubilization capacity for celecoxib. The dissolution behaviors of various tablets prepared with solidified surfactants were compared to those of conventional celecoxib tablets in a simulated gastric fluid. Celecoxib tablets prepared using solidified surfactants showed improved dissolution behaviors when compared to the conventional counterparts. Fujicalin solidified Tween 80 was further analyzed by powder X-ray diffraction analysis, differential scanning calorimetry thermographs and reverse phase high performance liquid chromatography.

This study evaluated the moisturizing effect of serine-loaded solid lipid nanoparticles (serine-SLN) and polysaccharide-rich reed (Phragmites communis) root extract (RRE) incorporated in hydrogel bases. The hydrogels with serine-SLN and/or RRE were carefully applied on the volar forearm of human volunteers. Their moisturizing efficacy was evaluated by monitoring conductance values using a skin surface hygrometer. The values of the area under the normalized conductance-time curve (AUCC) were developed and compared as a parameter for the water holding capacity of the skin. Hydrogels with serine-SLN did not significantly moisturize the skin, while hydrogel containing 0.25% RRE produced a significant increase in the moisture content of the skin. However, adding more than 0.25% of RRE into the hydrogel base decreased the moisturizing effect due to the marked reduction of viscosity. Significantly enhanced moisturizing effect was observed with the hydrogel containing 0.25% RRE and 3% serine-SLN, with AUCC increased 2.21 times compared to than blank hydrogel. The results imply that effective delivery of serine into the skin is possible using lipid-based nanocarriers and RRE, which could be a promising strategy to moisturize the skin effectively.