Unexpected skin barrier influence from nonionic emulsifiers

Treatment-induced and Pre-existing Anti-peg Antibodies: Prevalence, Clinical Implications, and Future Perspectives

Polyethylene glycol (PEG) is a versatile polymer that is used in numerous pharmaceutical applications like the food industry, a wide range of disinfectants, cosmetics, and many commonly used household products. PEGylation is the term used to describe the covalent attachment of PEG molecules to nanocarriers, proteins and peptides, and it is used to prolong the circulation half-life of the PEGylated products. Consequently, PEGylation improves the efficacy of PEGylated therapeutics. However, after four decades of research and more than two decades of clinical applications, an unappealing side of PEGylation has emerged. PEG immunogenicity and antigenicity are remarkable challenges that confound the widespread clinical application of PEGylated therapeutics - even those under clinical trials - as anti-PEG antibodies (Abs) are commonly reported following the systemic administration of PEGylated therapeutics. Furthermore, pre-existing anti-PEG Abs have also been reported in healthy individuals who have never been treated with PEGylated therapeutics. The circulating anti-PEG Abs, both treatment-induced and pre-existing, selectively bind to PEG molecules of the administered PEGylated therapeutics inducing activation of the complement system, which results in remarkable clinical implications with varying severity. These include increased blood clearance of the administered PEGylated therapeutics through what is known as the accelerated blood clearance (ABC) phenomenon and initiation of serious adverse effects through complement activation-related pseudoallergic reactions (CARPA). Therefore, the US FDA industry guidelines have recommended the screening of anti-PEG Abs, in addition to Abs against PEGylated proteins, in the clinical trials of PEGylated protein therapeutics. In addition, strategies revoking the immunogenic response against PEGylated therapeutics without compromising their therapeutic efficacy are important for the further development of advanced PEGylated therapeutics and drug-delivery systems.

Current challenges ahead in preparation, characterization, and pharmaceutical applications of nanoemulsions

Nanoemulsions (NEs) are emulsions with particle size of less than around 100 nm. Reviewing the literature, several reports are available on NEs, including preparation, characterization, and applications of them. This review aims to brief challenges that researchers or formulators may encounter when working with NEs. For instance, when selecting NE components and identifying their concentrations, stability and safety of the preparation should be evaluated. When preparing an NE, issues over scale-up of the preparation as well as possible effects of the preparation process on the active ingredient need to be considered. When characterizing the NEs, the two major concerns are accuracy of the method and accessibility of the characterizing instrument. Also a highly efficient NE for clinical use to deliver the active ingredient to the target tissue with maximum safety profile is commonly sought. Throughout the review we also have tried to suggest approaches to overcome the challenges. This article is categorized under: Therapeutic Approaches and Drug Discovery > Emerging Technologies.

Investigation of anti-PEG antibody response to PEG-containing cosmetic products in mice

Polyethylene glycol (PEG), a polyether compound, is available in molecular weights from ∼300 g/mol to ∼10,000,000 g/mol. In the molecular weight range of ∼750 to ∼5000, PEG is commonly used in bioconjugation technology and nano-formulations to improve the circulation half-life of the formulations and increase their stability. In cosmetics, lower molecular weight PEG compounds such as PEG 60 or PEG 100 are widely used as emulsifiers and skin penetration enhancers. PEG polymers are generally recognized as biologically inert and non-immunogenic. However, it is recently reported that the "pre-existing" anti-PEG antibodies have been detected in high percentages of healthy individuals who have never received treatment with parenteral PEGylated formulations. To the best of our knowledge, we are the first to attempt to find an explanation for the source of pre-existing anti-PEG antibodies in healthy individuals. In a murine study, we demonstrated that topically applied PEG derivatives, present in two commercially available cosmetic products, could efficiently penetrate the stratum corneum and reach the systemic circulation. The skin penetration of PEG derivatives was further enhanced in injured or otherwise compromised skin. Daily application of cosmetic PEG derivatives primed the immune system, inducing anti-PEG IgM production. Anti-PEG IgM was detected by Day 14 in mice with normal skin, while anti-PEG IgM was detected as early as day 7 in mice with compromised skin. In addition, in mice with pre-induced circulating levels of anti-PEG IgM, topically applied PEG derivatives from cosmetic products appeared to bind to the pre-induced anti-PEG IgM, lowering blood levels. Current results indicate that PEG derivatives in cosmetic products may be an important contributor to the source of the "pre-existing" anti-PEG antibodies that have been detected in healthy individuals.

Safety Assessment of Starch Nanoparticles as an Emulsifier in Human Skin Cells, 3D Cultured Artificial Skin, and Human Skin

Emulsion systems are widely used in various industries, including the cosmetic, pharmaceutical, and food industries, because they require emulsifiers to stabilize the inherently unstable contact between oil and water. Although emulsifiers are included in many products, excessive use of emulsifiers destroys skin barriers and causes contact dermatitis. Accordingly, the consumer demand for cosmetic products made from natural ingredients with biocompatibility and biodegradability has increased. Starch in the form of solid nanosized particles is considered an attractive emulsifier that forms and stabilizes Pickering emulsion. Chemical modification of nanosized starch via acid hydrolysis can effectively provide higher emulsion stability. However, typical acid hydrolysis limits the industrial application of starch due to its high time consumption and low recovery. In previous studies, the effects of starch nanoparticles (SNPs) prepared by treatment with acidic dry heat, which overcomes these limitations, on the formation and stability of Pickering emulsions were reported. In this study, we evaluated the safety of SNPs in skin cell lines, 3D cultured skin, and human skin. We found that the cytotoxicity of SNPs in both HaCaT cells and HDF cells could be controlled by neutralization. We also observed that SNPs did not induce structural abnormalities on 3D cultured skin and did not permeate across micropig skin tissue or human skin membranes. Furthermore, patches loaded with SNPs were found to belong in the "No irritation" category because they did not cause any irritation when placed on human skin. Overall, the study results suggest that SNPs can be used as a safe emulsifier in various industries, including in cosmetics.

Alternative Excipients for Protein Stabilization in Protein Therapeutics: Overcoming the Limitations of Polysorbates

Given their safety and efficiency in protecting protein integrity, polysorbates (PSs) have been the most widely used excipients for the stabilization of protein therapeutics for years. In recent decades, however, there have been numerous reports about visible or sub-visible particles in PS-containing biotherapeutic products, which is a major quality concern for parenteral drugs. Alternative excipients that are safe for parenteral administration, efficient in protecting different protein drugs against various stress conditions, effective in protein stabilization in high-concentrated liquid formulations, stable under the storage conditions for the duration of the product's shelf-life, and compatible with other formulation components and the primary packaging are highly sought after. The aim of this paper is to review potential alternative excipients from different families, including surfactants, carbohydrate- and amino acid-based excipients, synthetic amphiphilic polymers, and ionic liquids that enable protein stabilization. For each category, important characteristics such as the ability to stabilize proteins against thermal and mechanical stresses, current knowledge related to the safety profile for parenteral administration, potential interactions with other formulation components, and primary packaging are debated. Based on the provided information and the detailed discussion thereof, this paper may pave the way for the identification or development of efficient excipients for biotherapeutic protein stabilization.

Skin Barrier Function in Infants: Update and Outlook

A good understanding of infant skin should provide a rationale for optimum management of the health of this integument. In this review, we discuss the skin barrier function of infants, particularly with reference to the use of diapers and baby wipes. The skin barrier of newborns continues to develop with age. Two years after birth, the barrier properties of infant skin closely resemble those of adult skin. However, several risk factors may contribute to impaired skin barrier and altered skin permeability in infants. Problems may arise from the use of diapers and baby wipes. The skin covered by a diaper is effectively an occluded environment, and thus is vulnerable to over-hydration. To date there has been no published information regarding dermal absorption of ingredients contained in baby wipes. Similarly, dermal absorption of topical ingredients in infants with underlying skin conditions has not been widely explored. Clearly, there are serious ethical concerns related to conducting skin permeation studies on infant skin. However, the increasing availability of non-invasive methods for in vivo studies is encouraging and offers new directions for studying this important patient group.

Safety and efficacy of combined essential oils for the skin barrier properties: In vitro, ex vivo and clinical studies

OBJECTIVE

To evaluate the safety and the synergistic effects of tea tree, lavender, eucalyptus and tangerine essential oils in combination on the skin using in vitro, ex vivo and clinical studies.

METHODS

The phototoxicity was predicted using 3T3 neutral red uptake phototoxicity test (OECD TG 432). Skin penetration was evaluated by confocal Raman microspectroscopy using direct application of essential oils to pig ears. For the clinical studies, 40 participants were enrolled and randomized in three groups: (1) lavender, eucalyptus and tangerine, (2) the same essential oils plus melaleuca and (3) placebo group. The skin was evaluated by noninvasive techniques before and after a 90-day period of topical use.

RESULTS

The essential oils were non-phototoxic, but the tangerine oil showed dose-dependent cytotoxicity (IC50: 33.1 µg/ml), presenting 35% of penetration in the viable epidermis. On the contrary, 17.7 µg/ml in combination was applied per day in the clinical study and the penetration rate for the combinations (10%, 1.77 µg/ml achieving the viable epidermis) guaranteed the safety, since in the clinical study, the application of the four essential oils improved skin barrier and morphologic skin characteristics, as well as increased skin hydration and decreased sebum levels, with no unwanted effects reported.

CONCLUSIONS

All essential oils studied were considered non-cytotoxic or non-phototoxic separately except tangerine, which present a dose-dependent cytotoxicity. Finally, the essential oils in combination in an appropriate amount were safe and effective in the improvement of the hydrolipidic balance and morphological properties of the skin.

Multi parametric biophysical assessment of treatment effects on xerotic skin

Background

Topical moisturizing products are widely used to alleviate the problems associated with xerotic skin. Their use affects many properties of the stratum corneum (SC) in a complex and interrelated manner. The range of measurement techniques available to the researcher has increased in recent years. However, few studies have looked for correlations between the different techniques for assessing how aspects of xerotic skin change over time as a result of topical moisturizer usage.

Objectives

A 3‐week in vivo study using an oil‐in‐water based moisturizing product and an untreated site was conducted to determine the clinical significance of and any correlations between a range of different approaches for the measurement of skin lipid content and also skin hydration and visual grading of dry skin.

Methods

A range of traditional and more recently developed skin measurement techniques have been used to examine a variety of SC properties in normal and xerotic skin during topical moisturizer usage.

Results

In vivo confocal Raman spectroscopy and analysis of SC lipids from tape strips both showed an increase in SC lipid level and organization after 3 weeks of moisturizer usage on xerotic skin. Hydration, measured both optically and electrically, also increased and skin barrier function improved, with strong correlations between the different measures of dryness being observed.

Conclusions

Strong correlations were observed between the skin measurements for lipid assessment and skin hydration with regard to the assessment of xerotic skin, providing valuable new information for future in vivo clinical research into dry and atopic skin.

Keywords

biophysical assessment, skin barrier, skin hydration, topical moisturizers, Xerosis

Optimal configuration of confocal Raman spectroscopy for precisely determining stratum corneum thickness: Evaluation of the effects of polyoxyethylene stearyl ethers on skin

Properties regarding stratum corneum (SC), the outermost membrane of the skin, remain an active area in dermatologic and cosmetic research. The reduced thickness of SC is associated with varied adverse statuses such as skin lipid deficiency, skin barrier dysfunctions and skin deceases, etc. Emulsifiers with existing irritative effects on skin components also face the risk of decreasing SC thickness. We have been focusing on the effects of PEGylated emulsifiers on the skin and have an interest in finding the role of their polyethylene glycol (PEG)-chain length in tuning skin irritations. With this aim, PEG-stearyl ethers with different numbers of hydrophilic chains were applied on the skin, and their influence on skin thickness was discovered to determine their skin barrier effect. Confocal Raman spectroscopy (CRS) with extensive application in skin research was used here. To obtain the precise determination of skin thickness, our secondary aim was to find the optimal CRS configuration referring to varied objectives and pinhole sizes where further study is still in demand. Therefore, SC thickness measured via eddy current approach served as reference. The applied PEG-stearyl ethers formed the system to achieve varied thicknesses. Results confirmed that the skin interactions rose with increasing PEG-chain length, however only up to a certain limit, with decreasing effects recorded from PEG-40 stearyl ether and no effects observed from PEG-100 stearyl ether. Simultaneously, CRS combined with water immersion objective and 50 μm pinhole presented the most consistent values to the references and exhibited better spectral intensity and signal-to-noise ratio. Correlation plots involving different cases of configurations were calculated for error corrections. Taken together, this work helps to identify the potential mechanisms governing the interactions between PEG-stearyl ethers and skin and offers powerful evidence of using CRS as a reliable alternative to obtain accurate thickness values.

Tracking heavy-water-incorporated confocal Raman spectroscopy for evaluating the effects of PEGylated emulsifiers on skin barrier

The class of PEGylated emulsifiers finds broad application in the pharmaceutical and cosmetic industry. We target on one of the categories of polyethylene glycol (PEG) alkyl ethers with different lipophilic and hydrophilic chain length and aim to examine their effects on the skin comprehensively. In this study, we employed confocal Raman spectroscopy for skin depth profiling and imaging. A unique probe of heavy water (D₂ O) was incorporated, which can be tracked percutaneously and simultaneously monitor the effects caused by emulsifiers. According to the results, most of the PEGylated emulsifiers caused changes in skin lipid content/organization and induced the alteration in relative water content/hydrogen bonding structure. The results obtained from the depth profiling analysis provided the possibility to estimate the least penetration depth of emulsifiers. Among them, PEG-20 ethers displayed the most penetration ability. Meanwhile, it is interesting to find that the treatment of emulsifiers also affected the spatial distribution of D₂ O whose differences were in line with the molecular skin variations. In particular, the isotopic H/D substitution in the skin was highlighted in detail. This result supports the possibility to use D₂ O as an excellent and cost-effective probe to evaluate the skin barrier function.

Safety Assessment of Monoglyceryl Monoesters as Used in Cosmetics

The Expert Panel for Cosmetic Ingredient Safety (Panel) assessed the safety of 44 monoglyceryl monoesters that are structurally constituted as the esterification products of glycerin and carboxylic acids (the majority of which are fatty acids); 36 of these monoesters were previously reviewed by the Panel, and 8 are reviewed herein for the first time. Most of the monoglyceryl monoesters have several reported functions in cosmetics, but the most common function among the ingredients is skin conditioning agent; a few are reported to function only as surfactant-emulsifying agents. The Panel reviewed relevant new data, including frequency and concentration of use and considered the data from previous Cosmetic Ingredient Review reports. The Panel concluded that these ingredients are safe in cosmetics in the present practices of use and concentration described in this safety assessment.

Systematic Investigation of the Effect of Non-Ionic Emulsifiers on Skin by Confocal Raman Spectroscopy-A Comprehensive Lipid Analysis

Non-ionic emulsifiers are commonly found in existing pharmaceutical and cosmetic formulations and have been widely employed to enhance the penetration and permeation of active ingredients into the skin. With the potential of disrupting skin barrier function and increasing fluidity of stratum corneum (SC) lipids, we herein examined the effects of two kinds of non-ionic emulsifiers on intercellular lipids of skin, using confocal Raman spectroscopy (CRS) with lipid signals on skin CRS spectrum. Non-ionic emulsifiers of polyethylene glycol alkyl ethers and sorbitan fatty acid esters were studied to obtain a deep understanding of the mechanism between non-ionic emulsifiers and SC lipids. Emulsifier solutions and dispersions were prepared and applied onto excised porcine skin. Water and sodium laureth sulfate solution (SLS) served as controls. SC lipid signals were analysed by CRS regarding lipid content, conformation and lateral packing order. Polyethylene glycol (PEG) sorbitan esters revealed no alteration of intercellular lipid properties while PEG-20 ethers appeared to have the most significant effects on reducing lipid content and interrupting lipid organization. In general, the polyoxyethylene chain and alkyl chain of PEG derivative emulsifiers might indicate their ability of interaction with SC components. HLB values remained critical for complete explanation of emulsifier effects on skin lipids. With this study, it is possible to characterize the molecular effects of non-ionic emulsifiers on skin lipids and further deepen the understanding of enhancing substance penetration with reduced skin barrier properties and increased lipid fluidity.

Assessment of dynamic bioaccessibility of curcumin encapsulated in milled starch particle stabilized Pickering emulsions using TNO's gastrointestinal model

Pickering emulsions stabilized by milled starch particles have been developed as a novel food-grade formulation to enhance the bioaccessibility of poorly soluble bioactive compounds (i.e., curcumin) by controlling the digestion of lipids in the human gastrointestinal (GI) tract. The dynamic bioaccessibilities of curcumin with and without encapsulation in the Pickering emulsion were evaluated using the dynamic TNO's gastrointestinal (TIM-1) model. For comparison, their digestion profiles were also studied using the in vitro pH-stat lipolysis model. With the combination of two in vitro models, the effect of the milled starch particle stabilized Pickering emulsions on the bioaccessibility of curcumin was fully revealed. There are large differences between the bioaccessibility values of curcumin samples obtained by these two models. Simulated small intestinal lipolysis in the pH-stat model revealed that the bioaccessibility of curcumin encapsulated in the Pickering emulsion was 27.6%, which was larger than 22.1% for free curcumin suspended in the bulk oil phase. The bioaccessibility of curcumin was 50.7% in the emulsion system and 7.8% in the bulk oil when using the TIM-1 model, which simulated the digestion conditions of the entire human GI tract. The digestion mechanism of the milled starch particle stabilized Pickering emulsions in the upper GI tract was well elucidated by the TIM-1 model. The gradual release and improved dissolution profile of the milled starch particle stabilized Pickering emulsions highlighted their potential as delivery systems for lipophilic bioactive compounds.

Potential treatment of atopic dermatitis: tolerability and safety of cream containing nanoparticles loaded with hydrocortisone and hydroxytyrosol in human subjects

Hydrocortisone (HC), topical glucocorticoid along with hydroxytyrosol (HT), and anti-microbial- and anti-oxidant-loaded chitosan nanoparticles (CSNPs) were prepared in large scale and analyzed for their adverse effects on healthy human skin followed by repeated applications. Ten subjects were randomized to receive test (HC-HT CSNPs) and vehicle samples (aqueous (AQ) cream). They were applied on the arms for 28 days, and transepidermal water loss (TEWL), erythema intensity, and irritation score were measured. Blood samples were analyzed for blood hematology, blood biochemistry, and adrenal cortico-thyroid hormone (ACTH) levels. Skin biopsy was obtained to assess histopathological changes in the skin. HC-HT CSNP AQ cream was stored at 4, 25, and 45 °C for a period of 1 year, and its stability was assessed by monitoring their physical appearances, particle size, and pH. Spherical-shaped NPs were successfully upscaled using spinning-disc technology, with insignificant changes in particle size, zeta potential, and incorporation of drugs as compared to the well-established laboratory method. Particle size of HC-HT CSNPs was < 250 nm, and HC-HT CSNPs AQ cream remained stable when stored at 25 °C. TEWL and erythema intensity for 28-day application did not indicate any signs of local irritation, redness, and toxicity, which were confirmed by normal Draize skin irritation scoring system and skin hematoxylin and eosin (H&E) staining results. Comparative results of blood hematology, blood biochemistry, and adrenal cortico-thyroid hormone level at day 0 and day 28 were not significant, indicating non-systemic toxicity. In conclusion, HC-HT CSNP AQ cream is safe, well-tolerated, and non-toxic, which may be useful in treating atopic dermatitis.

Combining in vitro digestion model with cell culture model: Assessment of encapsulation and delivery of curcumin in milled starch particle stabilized Pickering emulsions

To investigate the encapsulation and oral delivery efficiency of milled starch particles stabilized Pickering emulsions for lipophilic bioactive compounds, in vitro digestion model coupled with Caco-2 cells models were used. Physicochemical and biological properties of curcumin encapsulated Pickering emulsions were analyzed regarding to emulsion structure, curcumin retention, in vitro digestion, in vitro anti-proliferate ability and cellular uptake. Milled starch particles stabilized Pickering emulsion system was able to protect curcumin against harsh gastric conditions. Around 80% of the encapsulated curcumin was retained after 2 h of simulated gastric digestion. By being encapsulated in Pickering emulsion, the bioaccessibility of curcumin was increased from 11% for curcumin in bulk oil phase to 28% under simulated intestinal digestion process. The resulting curcumin-loaded micelle phase from digested emulsion exhibited significant anti-cancer ability and enhanced cellular uptake. This research provides an exploratory study on the possible future application of milled starch particles stabilized Pickering emulsions as nutraceutical delivery vehicles in the creation of novel functional foods.

Evaluation of a biosurfactant extract obtained from corn for dermal application

At present, there is an increasing demand to improve the sustainability of surface-active compounds in dermal formulations. Biosurfactants, which are derived from living cells, are considered to be more environmentally friendly than synthetic surfactants. Thus, the use of biosurfactants is a promising strategy for the formulation of more environmentally friendly and sustainable dermal products. In this work, a biosurfactant extract (BS) obtained from corn wet-milling industry was studied for its potential use in dermal formulations. The corn derived BS possesses good surface-active properties and was found to be a suitable co-stabilizer for nanoemulsions and nanocrystals for dermal application. It also possesses antioxidative and skin protective properties and was also able to increase the dermal penetration efficacy for lipophilic actives. In dermal formulations the BS can therefore be used as co-stabilizer with antioxidative and penetration enhancing properties at the same time.

Innovative Natural Ingredients-Based Multiple Emulsions: The Effect on Human Skin Moisture, Sebum Content, Pore Size and Pigmentation

The increased interest in natural cosmetics has resulted in a higher market demand for preservative-free products based on herbal ingredients. An innovative W/O/W type emulsions containing herbal extracts were prepared directly; its cation form was induced by an ethanolic rosemary extract and stabilized using weak herbal gels. Due to the wide phytochemical composition of herbal extracts and the presence of alcohol in the emulsion system, which can cause skin irritation, sensitization or dryness when applied topically, the safety of the investigated drug delivery system is necessary. The aim of our study was to estimate the potential of W/O/W emulsions based on natural ingredients for skin irritation and phototoxicity using reconstructed 3D epidermis models in vitro and to evaluate in vivo its effect on human skin moisture, sebum content and pigmentation by biomedical examination using a dermatoscopic camera and corneometer. According to the results obtained after in vitro cell viability test the investigated emulsion was neither irritant nor phototoxic to human skin keratinocytes. W/O/W emulsion did not cause skin dryness in vivo, despite the fact that it contained ethanol. We can conclude that the emulsion is safe for use as a leave-on product due to the positive effect on human skin characteristics or as a semisolid pharmaceutical base where active compounds could be encapsulated.

Safety assessment of starch-based personal care products: Nanocapsules and pickering emulsions

The safety profile of the ingredients used in topical dosage forms and its evaluation is an issue of utmost importance. A suitable equilibrium between safety and efficacy is crucial before promoting a dermatological product. The aim of this work was to assess the safety and biological effects of starch-based vehicles (St-BV) used in such products. The hazard, exposure and dose-response assessment were used to characterize the risk of each ingredient. The EpiSkin™ assay and human repeat insult patch tests were performed to compare the theoretical safety assessment to in vitro and in vivo data. The efficacy of the St-BV was studied using biophysical measurements in human volunteers during 28 days, showing that all ingredients and their combinations were safe for the consumer. Tissue viability determined using the EpiSkin™ testing reached values between 84.0 ± 5.0% and 98.0 ± 8.6% after application of St-BV, which were considered as non-irritant to the skin. These observations were confirmed by the in vivo studies where the St-BV did not induce any sensitization on the volunteers, being safe for human use. Moreover, St-BV increased skin hydration and microcirculation, emerging as an attractive alternative to chemical raw materials.

Development of medicated foams that combine incompatible hydrophilic and lipophilic drugs for psoriasis treatment

The focus was on the development of medicated foam for incorporation of two incompatible active agents for psoriasis treatment; i.e., lipophilic cholecalciferol, and hydrophilic salicylic acid. Emphasis was given to formulation of a propellant-free foam, with sufficient foaming properties, physical and chemical stability, and low irritancy potential to maintain relevance for later translation into clinical practice. Various excipients and concentrations were examined to achieve suitable foam stability parameters, viscoelasticity, and bubble-size, which relate to foamability and spreadability. The major positive impact on these properties was through a combination of surfactants, and by inclusion of a viscosity-modifying polymer. Incorporation of the incompatible drugs was then examined, noting the instability of cholecalciferol in an acidic environment, with the design aim to separate the drug distributions among the different foam phases. Cholecalciferol was stabilized in the emulsion-based foam, with at least a 30-fold lower degradation rate constant compared to its aqueous solution. The composition of the emulsion-based foam itself protected cholecalciferol from degradation, as well as the addition of the radical-scavenging antioxidant tocopheryl acetate to the oil phase. With the patient in mind, the irritancy potential was also examined, which was below the set limit that defines a non-irritant dermal product.

Enhanced interfacial activity of multi-arm poly(ethylene oxide) star polymers relative to linear poly(ethylene oxide) at fluid interfaces

Interfacial tension reduction, dynamic dilatational elasticity and extent of adsorption were investigated for linear poly(ethylene oxide) (PEO) chains of varying molecular weight and for PEO star polymers with an average of 64 arms per star at air/water, xylene/water, and cyclohexane/water interfaces.

An Overview of Novel Surfactants for Formulation of Cosmetics with Certain Emphasis on Acidic Active Substances

Novel surfactants which are nowadays available for incorporation into various formulations of personal care and cosmetic products are numerous, implying a permanent need for their classification. This overview provides essential information relating to synthesis, basic physicochemical characteristics, application and other relevant data on surfactants currently used in cosmetic products. In the second part of the paper an outline of acidic active substances with significant application in cosmetic products is given, as well as the problems that arise during preparation/manufacture of the containing formulations, accompanied with the review of scientific publications and other available reliable data dealing with the incorporation of these actives in the cosmetic formulations stabilized with novel (mainly natural) surfactants.

The influence of microemulsion structure on their skin irritation and phototoxicity potential

The purpose of this study was to examine skin irritation and phototoxicity potentials of several microemulsions (ME), all comprising approximately the same percentage of surfactant mixture, but varying oil/water content and consequently inner structure being either droplet-like (o/w ME, o/w ME carbomer, w/o ME and w/o ME white wax) or lamellar (gel-like ME). Two different in vitro methods were used: MTT assay (performed either on reconstructed human epidermis (RHE) or NCTC 2544 cells) and pig ear test. Neither assay revealed the difference among ME with droplet-like structure. Then again, pig ear test and MTT assay performed on RHE indicated that gel-like ME is more irritant compared to other tested ME, whereas no difference among formulations were observed by MTT assay on NCTC 2544 cells. The reasonable explanation is destruction and consequently uniform structure of ME upon dilution that is inevitable for testing on cell cultures. The results of phototoxicity test again indicated the increased potential of gel-like ME to cause adverse effects on skin. It can be concluded that for ME consisting of the same amount of identical surfactants but having different structure the latter represent a crucial factor that determines their dermal toxicity.

Triamcinolone spray: no-rub application as effective as rub application

BACKGROUND

Adherence to therapy is important to achieve successful treatment outcomes. Although effective, topical treatments in dermatology may result in sticky skin or may be too time-consuming to apply, thereby creating adherence issues. Spray formulations have excellent products aesthetics, but may require a 2-step application process.

AIMS

This study was conducted to determine whether the spray formulation of triamcinolone acetonide (TAC) 0.2% works equally well in a no-rub and rub application process.

METHODS

Fifty patients 18 years of age and older with mild symmetrical arm or leg eczema or atopic dermatitis were enrolled in a 2-week investigator-blinded study. One limb was randomized to be treated with TAC spray and no rubbing, and the other was to be treated with TAC spray and rubbing. Patients applied the spray three times daily for 2 weeks. The use of moisturizers was not permitted.

RESULTS

After 2 weeks, there was a highly clinical and statistical (P < 0.001) improvement in all investigator and patient parameters evaluated with both the no-rub and rub techniques. There was no difference in final assessment scores between the no-rub and rub applications (P > 0.7), and no study product tolerability issues were identified. Transepidermal water loss and corneometry measures revealed no issues in skin barrier impairment even though patients were not permitted to use moisturizers.

CONCLUSION

This study demonstrates the application parity between a no-rub and rub application of TAC spray in the absence of a moisturizer. Both techniques resulted in clinical and significant improvement in eczema and atopic dermatitis and neither resulted in skin barrier issues.

Monitoring the distribution of surfactants in the stratum corneum by combined ATR-FTIR and tape-stripping experiments

Combined ATR-FTIR (attenuated total reflection-Fourier transform infrared) spectroscopy and tape-stripping experiments in vitro on porcine ear skin were used to investigate the spatial distribution of different surfactants in the stratum corneum (SC). To reveal a possible connection between the size of the formed micelles and skin penetration, dynamic light-scattering measurements of the aqueous surfactant solutions were also taken. Compared to an alkyl polyglycoside and sucrose laurate, a deeper skin penetration of the anionic surfactants sodium dodecyl sulfate (SDS) und sodium lauryl ether sulfate (SLES) could be related to a smaller size of the formed micelles. Beside the differences in spatial distribution, a link between the physical presence of anionic surfactants in the SC and a decrease of skin hydration was found. Furthermore, the incorporation of SDS and SLES into the SC, even after a brief, consumer-orientated washing procedure with commercially available hair shampoos, was confirmed.

Hydrogel-based ultra-moisturizing cream formulation for skin hydration and enhanced dermal drug delivery

To develop an external vehicle for skin hydration and enhanced dermal drug delivery, a hydrogel-based ultra-moisturizing cream (HUMC) was successfully formulated with carbopol 934P, urea, Tinocare GL, grape seed oil, and other excipients. The HUMC showed plastic flow behavior due to a gel structure with a cream base. Different types of drug-free vehicles such as a hydrogel, conventional cream (CC), and three HUMCs were prepared and subjected to an in vivo skin hydration test on a hairless mouse using a corneometer. Hydration effect (∆AU) was in the order of HUMC2>HUMC1 ≥ CC>HUMC3>hydrogel. Using nile red (NR) and 5-carboxyfluorescein (5-CF) as lipophilic and hydrophilic fluorescent probes, respectively, in vitro skin permeation and accumulation studies were conducted using Franz diffusion cells. The values of steady-state flux (Jss, ng/h/cm(2)) were obtained: 74.8 (CC), 145.6 (HUMC1), and 161.9 (HUMC2) for NR delivery; 6.8 (CC), 8.3 (HUMC1), and 10.9 (HUMC2) for 5-CF delivery. The amounts retained in the skin at 12 h (Qr, ng/cm(2)) were determined: 86.4 (CC) and 102.0 (HUMC2) for NR; and 70.1 (CC) and 195.6 (HUMC2) for 5-CF. Confocal microscopy was used to visualize the distribution of the fluorescent probes. NR tended to be localized into the deeper part of the skin with adipose tissue whereas 5-CF localized in the upper layer of the skin. Thus we propose that HUMC2 is an efficacious vehicle for skin hydration and enhances dermal delivery of lipophilic and hydrophilic drugs.

Safety assessment and biological effects of a new cold processed SilEmulsion for dermatological purpose

It is of crucial importance to evaluate the safety profile of the ingredients used in dermatological emulsions. A suitable equilibrium between safety and efficacy is a pivotal concern before the marketing of a dermatological product. The aim was to assess the safety and biological effects of a new cold processed silicone-based emulsion (SilEmulsion). The hazard, exposure, and dose-response assessment were used to characterize the risk for each ingredient. EpiSkin assay and human repeat insult patch tests were performed to compare the theoretical safety assessment to in vitro and in vivo data. The efficacy of the SilEmulsion was studied using biophysical measurements in human volunteers during 21 days. According to the safety assessment of the ingredients, 1,5-pentanediol was an ingredient of special concern since its margin of safety was below the threshold of 100 (36.53). EpiSkin assay showed that the tissue viability after the application of the SilEmulsion was 92 ± 6% and, thus considered nonirritant to the skin. The human studies confirmed that the SilEmulsion was not a skin irritant and did not induce any sensitization on the volunteers, being safe for human use. Moreover, biological effects demonstrated that the SilEmulsion increased both the skin hydration and skin surface lipids.

Safety Assessment of Alkyl PEG Ethers as Used in Cosmetics

The CIR Expert Panel assessed the safety of Alkyl PEG Ethers as used in cosmetics. These ingredients primarily function in cosmetics as surfactants, and some have additional functions as skin-conditioning agents, fragrance ingredients, and emulsion stabilizers. The Panel reviewed available relevant animal and clinical data, as well as information from previous CIR reports; when data were not available for individual ingredients, the Panel extrapolated from the existing data to support safety. The Panel concluded that the Alkyl PEG ethers are safe as used when formulated to be nonirritating, and the same applies to future alkyl PEG ether cosmetic ingredients that vary from those ingredients recited herein only by the number of ethylene glycol repeat units.

Effect of moisturizers on epidermal barrier function

A daily moisturizing routine is a vital part of the management of patients with atopic dermatitis and other dry skin conditions. The composition of the moisturizer determines whether the treatment strengthens or deteriorates the skin barrier function, which may have consequences for the outcome of the dermatitis. One might expect that a patient's impaired skin barrier function should improve in association with a reduction in the clinical signs of dryness. Despite visible relief of the dryness symptoms, however, the abnormal transepidermal water loss has been reported to remain high, or even to increase under certain regimens, whereas other moisturizers improve skin barrier function. Differing outcomes have also been reported in healthy skin: some moisturizers produce deterioration in skin barrier function and others improve the skin. Possible targets for barrier-influencing moisturizing creams include the intercellular lipid bilayers, where the fraction of lipids forming a fluid phase might be changed due to compositional or organizational changes. Other targets are the projected size of the corneocytes or the thickness of the stratum corneum. Moisturizers with barrier-improving properties may delay relapse of dermatitis in patients with atopic dermatitis. In a worst-case scenario, treatment with moisturizing creams could increase the risks of dermatitis and asthma.

Damage/recovery by additive on lipid membrane as a mimicry of human stratum corneum

The effects of sodium dodecyl sulfate (SDS) on the model lipid membrane of human stratum corneum, composed of three main lipids of ceramide III, palmitic acid, and cholesterol, have been examined as a function of exposure period. Cholesterol first got to elute, palmitic acid followed it late, and the remaining solid was mainly ceramide III. The removal of lipids influenced the configurational structure of remaining lipid and the intralayer structure of lamellae. Monitoring of structural reorganization in the damaged membrane was carried out on the recovering procedure of palmitic acid and cholesterol. Both lipids were penetrated in the damaged membrane and recovered mostly the configurational lipid structure and the lamellar structure. Especially, it can be noted that cholesterol is more effective than palmitic acid on recovery.