Development Of Topical Products Research Articles

Mitragyna speciosa ethanolic extract: Extraction, anti-inflammatory, cytotoxicity, and transdermal delivery assessments

This study aimed to investigate the efficiency of extraction procedures for Mitragyna speciosa Korth (M. speciosa) as well as the anti-inflammatory, cytotoxicity, and transdermal delivery potential of M. speciosa ethanolic extract. Extraction of M. speciosa leaves was conducted using three different methods: maceration, ultrasonic-assisted extraction (UAE), and UAE with maceration. The extraction yields obtained were 9.3–23.1% with a mitragynine content of 7.9–10.2%. Mitragynine remaining of M. speciosa extracts was greater than 97% after 30-d storage at various conditions. Cytotoxicity study towards various skin cells reveals that cell growth half inhibitory concentrations (IC50) of M. speciosa extract ranged from 1.4 ± 0.0 to 2.5 ± 0.2 mg/mL. M. speciosa extract exhibited dose-dependent inhibitory effects on nitric oxide production (IC50 = 147.8 ± 9.0 µg/mL) and suppressed pro-inflammatory cytokine expression levels. Ex vivo assessment using porcine ear skin reveals that skin permeation of mitragynine from M. speciosa extract was restricted with permeation flux ranging from 0.4 ± 0.1 to 11.6 ± 1.1 µg·cm−2·h−1 and skin deposition at 24 h ranged from 8.7 ± 2.6 to 60.5 ± 16.2 µg·cm−2. Vehicle composition and lipophilicity were found to be determinants of mitragynine permeation. The mixture of hydrophilic chemical enhancers—propylene glycol and diethylene glycol monoethyl ether—as M. speciosa extract vehicle yielded the highest skin permeability coefficient of mitragynine. These findings offer valuable information that can be utilized for the transdermal and/or topical product development of mitragynine and M. speciosa extract.

Dose-dependent effect on skin permeation of polar and non-polar compounds

The study of the relationship between the amount of drug applied to the skin and fraction of drug absorbed can improve our understanding of finite-dose percutaneous absorption in the development of topical products and risk assessment of hazardous chemical exposure. It has been previously shown that an increase in the dose applied to the skin leads to a decrease in the fraction of drug permeated the skin (dose-dependent effect). The objective of this research was to examine the dose-dependent effect using permeants of varying physiochemical properties. The dose-dependent effect was studied using human epidermal membrane under finite dose conditions in Franz diffusion cell with model permeants at doses ranging from 0.1 to 200 μg. The dose-dependent effect was evident with model permeants caffeine, corticosterone, dexamethasone, and estradiol, consistent with the relationship of decreasing fraction of dose permeated the skin at increasing the applied dose. However, no significant dose-dependent effect was observed for the polar model permeants urea, mannitol, tetraethyl ammonium, and ethylene glycol, suggesting different transport mechanisms for these permeants. It was also found that, at relatively high doses, estradiol, dexamethasone, and corticosterone could increase the permeation of polar and lipophilic permeants, which could counter the dose-dependent effect under the conditions studied.

In Silico Models for Skin Sensitization and Irritation.

The assessment of skin irritation, and in particular of skin sensitization, has undergone an evolution process over the last years, pushing forward to new heights of quality and innovation. Public and commercial in silico tools have been developed for skin sensitization and irritation, introducing the possibility to simplify the evaluation process and the development of topical products within the dogma of the computational methods, representing the new doctrine in the field of risk assessment.The possibility of using in silico methods is particularly appealing and advantageous due to their high speed and low-cost results.The most widespread and popular topical products are represented by cosmetics. The European Regulation 1223/2009 on cosmetic products represents a paradigm shift for the safety assessment of cosmetics transitioning from a classical toxicological approach based on animal testing, towards a completely novel strategy, where the use of animals for toxicity testing is completely banned. In this context sustainable alternatives to animal testing need to be developed, especially for skin sensitization and irritation, two critical and fundamental endpoints for the assessment of cosmetics.The Quantitative Risk Assessment (QRA) methodology and the risk assessment using New Approach Methodologies (NAM) represent new frontiers to further improve the risk assessment process for these endpoints, in particular for skin sensitization.In this chapter we present an overview of the already existing models for skin sensitization and irritation. Some examples are presented here to illustratetools and platforms used for the evaluation of chemicals.

Skin irritation and potential antioxidant, anti-collagenase, and anti-elastase activities of edible insect extracts

This study aimed to investigate antioxidant, anti-aging, and irritation properties of Thai edible insect extracts, including Bombyx mori, Omphisa fuscidentalis, Euconocephalus sp., Patanga succincta, Acheta domesticus, and Lethocerus indicus. Insects were extracted by 2 different methods, including maceration using ethanol or hexane and digestion using DI water. Then the extracts were determined for protein content using bicinchoninic acid assay and antioxidant activities using 2,2′-azinobis (3-ethylbenzothiazoline-6-sulfonic acid), 2,2-diphenyl-1-picrylhydrazyl, ferric reducing antioxidant power, and ferric thiocyanate assays. Anti-aging activities were investigated by determination of collagenase and elastase inhibitory activities using spectrophotometric assay. Maceration by hexane yielded the highest extract content, whereas aqueous extract from digestion possessed the significantly highest protein content and biological activities (p < 0.05). Interestingly, aqueous extracts of A. domesticus possessed the significantly highest biological activities (p < 0.05) with Trolox equivalent antioxidant capacity value of 8.8 ± 0.1 mmol Trolox/mg, DPPH· inhibition of 19.5 ± 3.8%, equivalent concentration of 12.1 ± 0.7 µM FeSO4/mg, lipid peroxidation inhibition of 31.3 ± 2.4%, collagenase inhibition of 60.8 ± 2.1%, elastase inhibition of 17.0 ± 0.1%, and no irritation effect on chorioallantoic membrane and volunteers. Therefore, aqueous extract of A. domesticus would be suggested for further topical product development.

LB795 Topical Product Development: Role of Barrier Function, In-vitro Skin Irritation & Permeation Testing for a model drug

The Purpose of the study was to evaluate a model drug for topical application using various invitro screening models; skin barrier, invitro skin irritation and invitro skin permeation testing. The skin barrier function assessment was performed by Trans Epithelial Water Loss (TEWL) measurements. The skin irritation potential was assessed using the EpiDerm® in vitro model in which tissue viability was determined using the MTT conversion assay. The IVPT study was performed across dermatomed human fresh frozen skin using Franz type diffusion cells and drug content was analyzed using LCMS/MS.

Visualizing topical drug uptake with conventional fluorescence microscopy and deep learning

Mapping the uptake of topical drugs and quantifying dermal pharmacokinetics (PK) presents numerous challenges. Though high resolution and high precision methods such as mass spectrometry offer the means to quantify drug concentration in tissue, these tools are complex and often expensive, limiting their use in routine experiments. For the many topical drugs that are naturally fluorescent, tracking fluorescence emission can be a means to gather critical PK parameters. However, skin autofluorescence can often overwhelm drug fluorescence signatures. Here we demonstrate the combination of standard epi-fluorescence imaging with deep learning for the visualization and quantification of fluorescent drugs in human skin. By training a U-Net convolutional neural network on a dataset of annotated images, drug uptake from both high "infinite" dose and daily clinical dose regimens can be measured and quantified. This approach has the potential to simplify routine topical product development in the laboratory.

A stability-indicating ultra-fast liquid chromatography method for the assay of the main flavonoids of Achyrocline satureioides (Marcela) in porcine skin layers and nanoemulsions.

Achyrocline satureioides (marcela or macela) is a plant widely used in folk medicine in South America. Recently, there has been increasing interest for the development of skin care products containing A. satureoides extracts, due to its well-documented antioxidant, antiherpetic, and wound healing properties. The present study aimed to develop and validate a yet unexplored stability-indicating and robust ultra-fast liquid chromatography (UFLC) method for the simultaneous quantification of the main flavonoids of A. satureioides in extracts, nanoemulsions, and porcine skin layers. The chromatographic separation of flavonoids quercetin, luteolin, and 3-O-methylquercetin was performed on a Luna C18 analytical column (100 mm × 2.0 mm i.d.; particle size 2.5 μm) using isocratic elution with methanol/phosphoric acid 1% (48:52 v/v) with a flow rate of 0.3 mL/min at 40°C. The method was found to be specific, linear (R > 0.998), precise, accurate, and robust for all flavonoids assayed in A. satureioides extract, nanoemulsions, and porcine ear skin. A low matrix effect was noted for all complex matrices. The stability-indicating UFLC method was evaluated by submitting isolated flavonoids, a mixture of standards, and A. satureioides extract to acidic, alkaline, oxidative, UV-A/UV-C light, and thermal stress conditions. No peaks were found co-eluting with the flavonoids of interest in all matrices. The robustness of the method was confirmed using Plackett-Burman experimental design. The short run time (8 min) and reliability of the method could be useful for the determination of A. satureioides flavonoids in topical product development since extracts of this medicinal plant have been used to treat various skin disorders.

Fast Screening Methods for the Analysis of Topical Drug Products

Considering the recent regulatory requirements, the overall importance of in vitro release testing (IVRT) methods regarding topical product development is undeniable, especially when addressing particulate systems. For each IVRT study, several hundreds of samples are generated. Therefore, developing rapid reversed-phase high-performance liquid chromatography (RP-HPLC) methods, able to provide a real-time drug analysis of IVRT samples, is a priority. In this study, eight topical complex drug products exhibiting distinct physicochemical profiles were considered. RP-HPLC methods were developed and fully validated. Chromatographic separations were achieved on a XBridgeTM C18 (5 µm particle size, 150 mm × 2.1 mm), or alternatively on a LiChrospher® 100 RP-18 (5 µm particle size, 125 mm × 4.6 mm) at 30 °C, under isocratic conditions using UV detection at specific wavelengths. According to the physicochemical characteristics of each drug, different mobile phases were selected. Irrespective of the drug (hydrocortisone, etofenamate, bifonazole, clotrimazole, acyclovir, tioconazole, clobetasol, and diclofenac) and formulation, retention time values did not exceed 6.5 min. All methods were linear, specific, precise, and accurate at the intraday and interday levels, robust, and stable. These were successfully applied to establish product-specific IVRT profiles, thus providing a key database useful for topical pharmaceutical manufacturers.

269 Agent-based computational modeling of the human epidermis and applications

The ontogenesis and maintenance of human epidermis is well documented in the scientific literature. Under physiological conditions, processes such as epidermal cell proliferation, differentiation and eventual desquamation from the skin surface are coordinated to support epidermal homeostasis. We have developed an agent-based computational model of the human epidermis that recapitulates the biochemical and biomechanical aspects of the tissue physiology. Modeling is performed at the individual cell (“agent”) level and multiple agents are then allowed to follow their programming and interact with their neighbors. Although all programing is done at the cellular level, emerging properties of the system are manifested at the tissue level, such as dynamic steady state of the stratified epidermis, barrier to water loss as well as to external penetration of topical substances, steady state water and calcium profiles qualitative similar to the ones in the literature, etc. By appropriately adjusting the rate constants of the processes at the cellular level we have been able to achieve distinct tissue architectures corresponding to adult and infant epidermis. This approach allows us to perform experiments in silico by perturbing the system and monitoring its behavior, such as following complete removal of the Stratum Corneum. Moreover, the model was able to recapitulate clinical data of: a) the effects of a topical moisturizer, b) the dynamics of tissue penetration of a topically applied agent, c) skin barrier-related effects of topical treatment with a surfactant, and d) effects of a barrier-enhancing topical agent. In conclusion, computational modeling is a valuable tool for studying epidermal behavior and demonstrating product effects, which can be used to provide design guidelines for topical product development.

The revised EEMCO guidance for the in vivo measurement of water in the skin.

Noninvasive quantification of stratum corneum water content is widely used in skin research and topical product development. The original EEMCO guidelines on measurements of skin hydration by electrical methods and transepidermal water loss (TEWL) by evaporimeter published in 1997 and 2001 have been revisited and updated with the incorporation of recently available technologies. Electrical methods and open-chamber evaporimeters for measurement of TEWL are still the preferred techniques to measure the water balance in the stratum corneum. The background technology and biophysics of these instruments remain relevant and valid. However, new methods that can image surface hydration and measure depth profiles of dermal water content now available. Open-chamber measurement of TEWL has been supplemented with semiopen and closed chamber probes, which are more robust to environmental influence and therefore convenient to use and more applicable to field studies. However, closed chamber methods interfere with the evaporation of water, and the methods cannot be used for continuous monitoring. Validation of methods with respect to intra- and inter-instrument variation remains challenging. No validation standard or test phantom is available. The established methods for measurement of epidermal water content and TEWL have been supplemented with important new technologies including methods that allow imaging of epidermal water distribution and water depth profiles. A much more complete and sophisticated characterization of the various aspects of the dermal water barrier has been accomplished by means of today's noninvasive techniques; however, instrument standardization and validation remain a challenge.

Preparation of stable tea seed oil nano-particle emulsions by a low energy method with non-ionic surfactants

Tea seed oil nano-particle emulsions were prepared. Non-ionic surfactants containing Tween 80 and Span 80 (1:1, w/w) were mixed with propanol (3-9:1, w/w) to give Smix, which was thereafter mixed with tea seed oil. The mixture was titrated with water at 150 rpm to give clear or bluish and bluish-white emulsions. Twelve nano-particle emulsions with 64.64 to 72.73% Smix, 16.66 to 27.27% oil and 9.09 to 16.67% water with particle sizes between 207.00 to 430.10 nm, PDI of 0 to 0.4, ζ-potential of -42.00 to -49.63 mV, pH of 7.04 to 7.32 and 151.33 to 241.93 cps, were stable following an accelerated stability test and long term storage at room temperature and 4 and 45 ºC for 90 days, although one system (16.66% oil and 66.67% Smix) was separated. This nano-particle emulsion formulation is concise and feasible for an industrial development of topical products containing tea seed oil.

Isopropyl Myristate and Cocoa Butter are not Appropriate Positive Controls for Comedogenicity Assay in Asian Subjects

Background: Comedogenicity is an important consideration in development of topical products, such as cosmetics. An animal test using rabbit ear has long been served as a model for prediction of comedogenicity of topical products, but correlation to the human skin remained controversial. Isopropyl myristate and cocoa butter which are used as positive controls in animal test, also used in human clinical assay but report for the comedogenicity of those two positive controls in human, especially in Asian skin is limited. Objective: To assess the comedogenicity of isopropyl myristate and cocoa butter in Asian skin using a modified human model established by Mill and Kligman. Methods: We selected eight Asian subjects with prominent follicular orifices and the prone to acne type skin on the upper back. Two substances, isopropyl myristate and cocoa butter, were applied on the upper back skin three times a week for four weeks. Petrolatum and non-treated skin served as negative controls. Microcomedones were estimated by cyanoacrylate follicular biopsy at baseline and after four weeks of application. The number of follicles and microcomedones were determined by quantitative image analysis. Results: Microcomedone activities of isopropyl myristate and cocoa butter have no significant difference to negative controls in Asian skin. Conclusion: Comedogenic activity of isopropyl myristate and cocoa butter is too weak that those are not appropriate positive controls for clinical human assay in Asian skin. Further studies are necessary to determine appropriate positive controls in the human model for all ethnic populations.

Interactions between the stratum corneum and topically applied products: regulatory, instrumental and formulation issues with focus on moisturizers.

Virtually everyone in Europe will use at least one cosmetic product every day. The extensive use of cosmetics and results from measurements of quality of life in patients with skin diseases demonstrate the importance of a healthy skin. The skin is not only a barrier against desiccation and intrusion of harmful materials, but also an organ of social communication, where dry, scaly, rough stratum corneum is unappealing to touch, inducing anxiety and depression. Knowledge about the skin biochemistry and the use of noninvasive instruments facilitate the development of topical products and quantification of their effects. The presentation of the products and mode of action determine the regulatory demands and the approval process, as they can fall into different regulatory entities, such as cosmetics, medicinal products, medical devices and as other chemical products. The majority of the topical products on the market are regulated as cosmetics. For example, facial skin care and daily moisturizing routines are frequently used. However, despite visible relief of dryness symptoms, some products are reported to result in deterioration of the skin barrier function. New clinical outcomes show important clinical differences between formulations and the relapse of eczema. In a worst case scenario, treatment with a moisturizing cream may increase the risks of eczema and asthma. In the present overview, product presentations and mode of actions are reflected against the regulatory demands in Europe. The regulations are continuously revisited and new guidelines are being implemented, such as the new cosmetic regulation with advice on testing and responsible marketing.

Transdermal absorption enhancement of papain loaded in elastic niosomes incorporated in gel for scar treatment

Papain is one of the protease enzymes from Carica papaya latex which is widely used in dermatology for scar treatment. The aim of this study was to compare the penetration of papain from gel formulations containing niosomes and nanospheres loaded with papain. The vesicular sizes of all niosomes and nanospheres in the gel formulations were in the range of 220.7–520.2nm. Papain loaded in elastic niosomes and incorporated in gel exhibited the accumulate amounts and fluxes of 0.226mg/cm2 and 0.029mg/cm2/h in the whole rat skin and 0.220mg/cm2 and 0.037mg/cm2/h in the receiving solution, which were 3.10, 2.38 and 2.24, 2.25; 10.08, 7.78 and 4.92, 4.93; 4.86, 3.71 and 7.38, 7.38 times more than that from gel containing papain loaded in non-elastic niosomes, PLGA nanospheres and in solution, respectively, investigated by Franz diffusion cells at 6h. All gel formulations incorporated with papain loaded in niosomes and nanospheres gave no irritation on rabbit skin. Gel containing papain loaded in elastic niosomes gave superior chemical stability to gel containing free papain of 1.13, 1.29 and 1.35 times when stored at 4±2, 27±2 and 45±2°C after 3months, respectively. After 28days of application, gel containing papain loaded in elastic niosomes (GEN) exhibited higher reduction of hypertrophic scars of the induced scar on rabbits’ ears determined by a vernier caliper than gel base (GB), gel containing free papain (GS), and gel containing papain loaded in non-elastic niosomes (GNN) of 10.20, 2.73 and 2.31 times, respectively. For histological examination, the numbers of collagen fibres and the height of the scars treated with GEN were significantly decreased compared with the control group. This study has demonstrated the potential of niosomes, especially the elastic niosomes, for the enhancement of rat skin transdermal absorption of papain and the improvement of scar reduction in rabbit ear model which will be beneficial for the development of topical products for scar treatment.

Clinical Pharmacology for Development of Topical Dermatological Products: Present and Future Opportunities for Safety and Efficacy

The development of topical products for dermatological diseases represents an untapped opportunity for the clinical pharmacologist. Assessment of bioavailability of topical drugs and its utility in weighing benefit vs. risk has been unique and challenging, compared with assessments for conventional systemic drugs. However, with continued advances in analytical methods and growing interests in discovering biomarkers, the future opportunities for clinical pharmacology to advance topical drug development processes are enormous and will be limited only by our drive and determination to push science forward.

Assessment of the distribution of radiolabelled non-ionic multilamellar surfactant microvesicles following topical application to canine skin biopsies: a preliminary study

Non-ionic multilamellar surfactant vesicles (Spherulites) represent a new generation of active ingredient carriers used for the development of topical products. This study aimed to assess the distribution of non-ionic Spherulites into canine skin. A suspension of Spherulites labelled with encapsulated 14C-palmitic acid was applied to the epidermis of cutaneous biopsies. Control biopsies were treated with non-encapsulated probe or left untreated. The distribution of radioactivity was assessed in cryostat sections by autoradiography and by direct radioactive imaging. Examination of sections showed that signals from the non-encapsulated probe were present at the skin surface. The distribution of radioactivity from the encapsulated probe (in non-ionic Spherulites) showed signals in the living epidermis, in hair follicles and in the dermis. This study suggests that non-ionic Spherulites are able to penetrate deeply into the skin of the dog.

Sensitive and Ethnic Skin: A Need for Special Skin-Care Agents?

Sensitive skin is a complex problem with genetic, individual, environmental, occupational, and ethnic implications. Further work is needed to rank irritants and irritant reactions to classify sensitive skin on the basis of standard models. The development of topical products designed for sensitive and ethnic skin may be advisable to optimize drug activity with minimal side effects. The availability of transdermal systems for drug delivery highlights the problem. Occlusive transdermal patch systems for delivery of clonidine show sensitization rates of 34% in white women, 18% in white men, 14% in black women, and 8% in black men. Besides ethnic differences in transcutaneous penetration, individual and ethnic skin sensitivity may play an important role in determining both patient compliance and therapeutic efficacy of drugs and cosmetics; furthermore, a drug formulation considering skin physiology may prevent unwanted local and general adverse effects.