Tape Stripping Technique Research Articles

In vivo permeation of 2-phenoxyethanol in human skin

A number of baby wipe formulations contain 2-phenoxyethanol (PE) as a preservative and cetylpyridinium chloride (CPC) as a surfactant with antimicrobial activity. Previously, we reported the skin absorption of PE in porcine skin and human skin in vitro. In the present work, the permeation of PE from preparations with CPC and without CPC was investigated in human skin in vivo. The studies were conducted using Confocal Raman Spectroscopy (CRS) and tape stripping (TS) methods. The CRS studies showed that the area under the curve (AUC) of PE for the formulation with and without CPC were not significantly different (p > 0.05). The TS data indicated no significant difference in the amounts of PE recovered from tapes 1–6 for the preparation with and without CPC (p > 0.05). When comparing the in vitro and in vivo data, a correlation was observed between the cumulative amount of PE permeated through human skin in vitro at 24 h and the AUC as measured by CRS (r2 = 0.97). In addition, the cumulative amount of PE permeated through human skin in vitro at 24 h was found to correlate with the amount of PE recovered from tape 1 to 6 in vivo (r2 = 0.95). Both CRS and TS techniques demonstrated limitations in assessing the distribution of PE and CPC in the skin in vivo, primarily attributed to the Raman signal intensities of compounds under investigation and the variability in the amount of SC collected by TS. Despite the limitations of CRS and TS, the results from the present study add further insights to the in vitro permeation data. Additionally, the findings of the present study encourage the further development and application of CRS for non-invasive evaluation of topical skin formulations in vivo.

Characterising Skin Electrical Impedance Using Tape Stripping Methods: A Bioelectrical Study of a Porcine Model.

Background Recent advancements in ultra-low power electronics and wireless devices have facilitated the widespread adoption of wearable technology for fitness and health monitoring, paving the way for personalized medicine. Microneedle-based devices, comprising small epidermal patches that penetrate the skin's stratum corneum to potentially access biomarkers in the extracellular fluid of the viable epidermis, represent a promising innovation in this field. Objectives This project aimed to develop and validate a novel method to evaluate microneedle engagement in the skin in real-time. To our knowledge, there are no studies published to date that have characterized the electrical impedance of stratum corneum and epidermis using the tape stripping method to selectively remove cell layers. Additionally, no studies have been published comparing the electrical impedance of fresh to frozen-thawed porcine skin. The objective of this study was to develop and validate a novel method to evaluate microneedle engagement in skin, in real-time, that does not require processing of the tissue. Methods A tape stripping technique was employed to selectively remove the stratum corneum from fresh and frozen-thawed porcine skin samples which were then electrically characterized using an excitation frequency of 5 kHz with a peak Voltage of 1 V. Results This study demonstrated a mean impedance reduction of 97.08 ± 1.3 % for fresh porcine skin, and 98.04 ± 0.3 % for frozen-thawed porcine skin when transitioning from the surface stratum corneum to the viable epidermis. The correlation between the reduction of impedance and the number of tape strips across all 18 test sites was significant (r = 0.98, p < 0.00001). However, comparing the skin impedance of the fresh and frozen-thawed specimens showed poor equivalence, with the frozen-thawed sites approximately 5.5 times the impedance of the fresh sites before any tape stripping, and 4.19 times greater after 30 tape strips. Conclusions These findings suggest that monitoring for an interelectrode impedance decrease of greater than 95% between two projections of a microneedle device could provide a rapid and effective evaluation of skin engagement, crucial for advancing the development and clinical application of microneedle-based technologies in personalized medicine. The study also underscores the impact of the freeze-thaw process on the mechanical and electrical properties of skin, which is crucial for standardizing testing protocols.

Penetration rates into the stratum corneum layer: A novel quantitative indicator for assessing skin barrier function.

The stratum corneum (SC), the outermost layer of the skin epidermis, acts as an effective bi-directional barrier, preventing water loss (inside-outside barrier) and entry of foreign substances (outside-inside barrier). Although transepidermal water loss (TEWL) is a widely-used measure of barrier function, it represents only inside-outside protection. Therefore, we aimed to establish a non-invasive method for quantitative evaluation of the outside-inside barrier function and visually present a skin barrier model. Skin barrier damage was induced by applying a closed patch of 1% sodium dodecyl sulfate to the forearms of eight participants; they were instructed to apply a barrier cream on a designated damaged area twice daily for 5 days. The SC barrier was evaluated by measuring TEWL and fluorescein sodium salt penetration rate before, immediately after, and 5 days after damage. The penetration rate was assessed using tape-stripping (TS) technique and fluorescence microscopy. The rates of fluorescein sodium salt penetration into the lower layers of SC differed significantly based on the degree of skin barrier damage. The correlation between penetration rate and TEWL was weak after two rounds of TS and became stronger after subsequent rounds. Five days after skin barrier damage, the penetration rate of all layers differed significantly between areas with and without the barrier cream application. Our findings demonstrated that the penetration rate was dependent on skin barrier conditions. The penetration rate and corresponding fluorescence images are suitable quantitative indicators that can visually represent skin barrier conditions.

Increased expression of complement C3c, iC3b, and cells containing CD11b or CD14 in experimentally induced psoriatic lesion.

Psoriasis is a chronic inflammatory skin disease with a characteristic isomorphic reaction, i.e. the Köbner reaction, induced by slight epidermal trauma. In this study, the tape-stripping technique was used to induce the development of Köbner reaction in 18 subjects with psoriasis. Eight subjects developed a positive reaction. To study the early cellular changes, skin biopsies were taken at the baseline and subsequent time points of 2 h, 1 d, 3 d, and 7 d for the immunostaining of complement C3c, iC3b, and cells expressing complement receptor 3 (CD11b/CD18; a receptor of iC3b) or CD14. The results show that the positive Köbner reaction is associated with rapid (2 h-1 d) and sustained (3-7 d) increase in the expression of epidermal C3c and iC3b and dermal C3c. In addition, there was a positive correlation between CD11b+ and CD14+ cells in baseline and 2 h-1 d biopsies with a subsequent increase in CD11b+ and CD14+ cells in 3-7 d biopsies in the Köbner-positive group. In the Köbner-negative group, only a transient increase in epidermal iC3b at 2 h-1 d, as well as rapid (2 h-1 d) and sustained increase (3-7 d) in dermal iC3b and CD14+ cells, was observed. In experiments with cultured monolayer keratinocytes, a slight cell damage already at 30 mJ/cm2 ultraviolet B irradiation led to increased expression of C3c, but not iC3b. Therefore, there are marked differences between Köbner groups in respect to the expression of C3c, iC3b, and cells expressing CD11b or CD14. Of note is the rapid and sustained increase in epidermal C3c and iC3b in the positive Köbner reaction.

Development of Essential Oil-Loaded Polymeric Nanocapsules as Skin Delivery Systems: Biophysical Parameters and Dermatokinetics Ex Vivo Evaluation.

Essential oils (EOs) are natural antioxidant alternatives that reduce skin damage. However, EOs are highly volatile; therefore, their nanoencapsulation represents a feasible alternative to increase their stability and favor their residence time on the skin to guarantee their effect. In this study, EOs of Rosmarinus officinalis and Lavandula dentata were nanoencapsulated and evaluated as skin delivery systems with potential antioxidant activity. The EOs were characterized and incorporated into polymeric nanocapsules (NC-EOs) using nanoprecipitation. The antioxidant activity was evaluated using the ferric thiocyanate method. The ex vivo effects on pig skin were evaluated based on biophysical parameters using bioengineering techniques. An ex vivo dermatokinetic evaluation on pig skin was performed using modified Franz cells and the tape-stripping technique. The results showed that the EOs had good antioxidant activity (>65%), which was maintained after nanoencapsulation and purification. The nanoencapsulation of the EOs favored its deposition in the stratum corneum compared to free EOs; the highest deposition rate was obtained for 1,8-cineole, a major component of L. dentata, at 1 h contact time, compared to R. officinalis with a major deposition of the camphor component. In conclusion, NC-EOs can be used as an alternative antioxidant for skin care.

Enhanced Skin Deposition of Betamethasone Dipropionate from a Novel Formulation and Drug Delivery Technology.

Effective topical drug delivery is the essence of dermatologic treatment. The drug must be applied to the skin surface, be released from the vehicle, enter the stratum corneum, traverse the epidermis, and enter the dermis pharmacologically intact. New advances have improved emulsion-type formulation and drug delivery technology by encapsulating dispersed oil droplets in a robust multimolecular aqueous film of surfactants, oil, and water, enabling a multifold decrease in surfactant concentration compared to conventional creams. In the research reported here, we studied this new concept, termed polyaphron dispersion (PAD) technology, by comparing skin delivery of betamethasone dipropionate from a novel oil-in-water emulsion system of calcipotriene and betamethasone dipropionate (CAL/BDP) cream to that from a traditional topical suspension (CAL/BDP TS) utilizing in vitro and in vivo detection methods. The amount of BDP released from the CAL/BDP cream and CAL/BDP TS was evaluated using both in vitro Franz cell analysis and in vivo human tape stripping from ten female human volunteers after a single application of CAL/BDP cream or CAL/BDP TS. For the tape stripping analysis, 20 circular tape strips were taken from forearm application sites at 1, 2, 4, and 8h after application and analyzed for the amount of BDP in the tape strip using liquid chromatography-mass spectrometry (LC-MS). The in vitro Franz cell analysis demonstrated that the cumulative amount of BDP that diffused through the epidermis was statistically significantly greater for the CAL/BDP cream compared to the CAL/BDP TS at all time points. In addition, consistently higher amounts of BDP were recovered following CAL/BDP cream application than following CAL/BDP TS application at 1, 2, 4, and 8h following application utilizing the in vivo tape stripping technique. The novel PAD technology-based cream formulation delivered more BDP into the upper stratum corneum and lower epidermis than a traditional topical suspension.

Biochemical analysis, antioxidant, and antibacterial efficacy of the bee propolis extract (Hymenoptera: Apis mellifera) against Staphylococcus aureus-induced infection in BALB/c mice: In vitro and in vivo study

Abstract Background Antibiotic resistance to Staphylococcal infections has prompted the pharmaceutical and scientific community to consider alternate treatments. Propolis is a natural substance produced by honey bees (Hymenoptera: Apis mellifera) from the exudates of different plants. The aim of the current study was to evaluate the antibacterial activity of ethanolic extracts of Pakistani bee propolis (PBP) against Staphylococcus aureus in both in vitro and in vivo modeling. Methods The propolis sample was collected from the Kohat district and dried in the dark until processing. The antibacterial activity of the propolis extract was examined using the agar well diffusion method. The S. aureus culture was incubated on Mueller–Hinton agar media. Five different concentrations of propolis, 100, 200, 350, 500, and 650 μg/ml, were used. Gentamicin disc was used as a positive control. For in vivo assay, BALB/c mice with an average weight of 30 g were purchased. Bacteria were inoculated into mice by the tape stripping technique. After abscess formation, mice were treated with propolis extract. Results The mean zone of inhibition and standard deviation for each concentration were 17 ± 0.816 at 650 μg/ml, 14.6 ± 0.471 at 500 μg/ml, 12 ± 1.41 at 300 μg/ml, 9.6 ± 0.942 at 200 μg/ml, and 2.3 ± 0.471 at 100 μg/ml of the propolis extract against S. aureus. It was observed that by increasing the concentration of the propolis extract, the antibacterial and antioxidant activities also increased. The extracts showed less antibacterial potential compared to gentamicin. The abscess size was also decreased in mice groups treated with the propolis extract topically and orally in comparison with the untreated mice group. Conclusions To the author’s best knowledge, this study is the first attempt to demonstrate that an ethanolic PBP extract has antibacterial potential against S. aureus-induced infections.

101 PAH Exposure During Construction of Railroad Swithes with Creosote Impregnated Ties

Abstract Coal tar creosote, or creosote, is a by-product of the carbonization of coal to produce coke and has been used as a wood preservative since the late 19th century. Creosote is a mixture of many different compounds such as polycyclic aromatic hydrocarbons (PAH)s, phenols and cresols. Even though several PAHs are carcinogenic to humans, creosote is still used in impregnation of railway ties and electricity and telephone poles. Occupational exposure can occure from inhalation of creosote vapour or through skin contact. Dermal uptake is considered to be the most important route of exposure to PAHs. Even though the ratio between different PAHs may vary, measurements of 1-hydroxy-pyrene (1-HP) in urine is the common method for biological monitoring of occupational exposure to PAH. This study was conducted indoors in a facility where railroad switches are assembled with concrete or creosote impregnated wood ties. The aim of the study was to assess the workers´exposure to PAHs by (i) measuring PAH 16 in the breathing zone from whole shift samples, (ii) examining the dermal exposure of pyrene using a tape stripping technique, (iii) assessing the workers´ internal exposure by measuring 1-OHP in urine samples. The study show that during construction of railroad switches made from creosote impregnated ties workers get urinary levels of 1-OPH above the Biological Guidance Value during the work week. Dermal uptake seems to be the main route of exposure and preventive measures should be focused upon reducing the dermal exposure. Speaker Biography Pål Graff works as a Professor at the Norwegian National Institute of Occupational Health and Norwegian University of Life Sciences. His main research interests are exposure assessment and epidemiology.

Nanostructured Lipid Carrier (NLC) and Solid Lipid Nanoparticles (SLN) Based Hydrogel for Delivery of Etodolac: A Comparative Investigation on Dermal Pharmacokinetic on Rat Skin

Objectives: The present work focus on to create Solid lipid nanoparticles (SLN) and nanostructured lipid Carrier (NLC) as transporters for effective delivery of Etodolac (ETD). Methods: Etodolac stacked SLN and NLC were set up by melting emulsification and hardening at low temperature method and they were portrayed for molecule size, zeta potential, encapsulation efficacy and in vitro discharge rate. Ex vivo dermatokinetic by tape stripping technique was explored in rat skin utilizing altered Franz diffusion cells. The praticle size and the surface electrical charge (ZP) have been assessed following after manufacturing of dispersion. Results: The particles stayed in their colloidal range after production by melt emulsification method. For all nano dispersion the encapsulation efficacy was higher than 75%. Differential Scanning calorimetry (DSC) were performed to portray the physicochemical properties of the SLN and NLC. Approximately Same amount of Etodolac release was facilitated through skin of rats from SLN-SA and NLC-SA. Conclusion: Research work could be concluded as successful development of Etodolac loaded SLN and NLC to increase the encapsulation efficiency of colloidal lipid carriers with benefit of higher performance in terms of long term stability and impart a sustaining Etodolac topical effect as well as faster relief from pain associated with arthritis.

Facial Treatment with 3-O-Cetyl Ascorbic Acid for Improvement of Skin Texture: Uptake, Effectiveness, and In Vitro Carcinogenicity Assessment

Ascorbic acid (AA) is a water-soluble vitamin that is found at high concentrations in normal skin. The important and well-known benefits of using AA in skin health include the stimulation of collagen synthesis and the assistance of protection against photo-oxidative damages. To maintain stability and improve drug delivery to the active site, a variety of AA derivatives have been chemically synthesized. Among these compounds, we focus here on a lipophilic derivative, 3-O-cetyl ascorbic acid (3-CetylAA), which remains poorly characterized for cosmetic applications. Uptake analysis in three healthy human volunteers’ skin was conducted using a serial tape-stripping technique detecting 3-CetylAA (on average, 128 ± 27 pmol per µg) in the stratum corneum after a 5-h topical treatment when treated with 25 mM 3-CetylAA-containing cream for 13 days twice daily and continuously. Time-of-flight secondary ion mass spectrometry (ToF-SIMS) imaging of vertical cryosections of pig skin revealed the presence of 3-CetylAA in the epidermal layer after topical treatment with 3-CetylAA-containing cream. In sun-exposed human skin, 3-CetylAA improved the texture after treatment with 25 mM 3-CetylAA-containing cream for 4 weeks or more when used twice daily or continuously. An in vitro transformation assay using BALB/c 3T3 A31-1-1 cells demonstrated that 10 µM 3-CetylAA, which is the same concentration exhibited in vitro biological activities in another lipophilic AA derivative, 2-O-octadecyl ascorbic acid, was non-carcinogenic and did not potentiate the UVC-induced transformation frequency when applied for 3 days after UVC irradiation. These results demonstrate that 3-CetylAA is a promising candidate as a lipophilic derivative of AA for cosmetic purposes.

Efficient agent degradation within skin is important for decontamination of percutaneously exposed VX

Aim of the study Following percutaneous exposure to the nerve agent VX, the remaining intact agent within the skin after decontamination is of great concern. Consequently, this leads to prolonged agent release to the blood circulation resulting in sustained intoxication, which may complicate the medical management. The decontamination procedure used should therefore possess the ability for agent removal both on and within the skin. The efficacy of three decontamination procedures was evaluated by measuring VX and the primary degradation product ethyl methyl phosphonic acid (EMPA) penetrated through human skin and the amount remaining within the skin. Materials and methods Decontamination was initiated 5 min post-exposure to VX on human dermatomed skin. Experiments were conducted using an in vitro skin penetration model and the amount remaining within the skin was determined by combining the tape-stripping technique and acetylcholinesterase activity measurements. Results In control experiments without decontamination, higher amounts of VX were recovered in the deeper layers of skin compared to EMPA, which was primarily located in the stratum corneum. Both Reactive Skin Decontamination Lotion (RSDL) and the RSDL training kit (TRSDL) significantly reduced the amount of VX within the skin and decreased the penetration through the skin. However, the degradation ability of RSDL was demonstrated to be beneficial by the reduction of intact agents remaining in the skin compared to TRSDL without agent degradation capability. Soapy water decontamination caused a “wash-in” effect of VX with decreased agent amounts within stratum corneum but increased the amount VX penetrated through the skin. Conclusion Efficient skin decontamination of VX requires skin decontaminants reaching deeper layers of the skin, and that both absorption and degradation properties are important. In addition, the “wash-in” effect by using soapy water may enhance VX release to the blood circulation.

Cytokine concentration across the stratum corneum in atopic dermatitis and healthy controls

Tape stripping is a promising technique for assessment of epidermal biomarkers in inflammatory skin diseases. However, to facilitate its implementation in the clinical practice, a thorough validation regarding sampling strategy is needed. Knowledge of biomarkers variation in concentration across stratum corneum is scarce. Therefore, this study aimed to assess the variability of cytokines across stratum corneum using tape stripping technique by consecutive application of 21 adhesive tapes (D-squame) to lesional and non-lesional skin from 15 patients with atopic dermatitis (AD) and 16 healthy controls. Concentration of cytokines (IL-1α, IL-1b, IL-5, IL-18, IFN-γ, CCL17, CCL22, CCL27, CXCL8, CXCL10, TNF-α, TSLP, VEGFA) was determined in five different depths, using multiplex immunoassay. Comparing tape 4 with tape 21, no cytokine changed significantly in concentration in AD lesional skin. In AD non-lesional skin a small decrease was found for CCL17, CXCL8 and CXCL10. For healthy controls, a decrease was found for IL-1a, IL-1b, VEGFA and an increase for IL-18. Differences were found between AD skin and healthy control skin. Concentration of cytokines was stable across stratum corneum, indicating that sampling of only one tape from the stratum corneum is reliable in reflecting the overall cytokine milieu. Differences between AD and healthy skin confirm robustness of tape stripping for measuring cytokine levels.

Liquid chromatography method to assay tretinoin in skin layers: validation and application in skin penetration/retention studies

A liquid chromatography (LC) method for the quantification of tretinoin (TTN) in different matrices (adhesive tape, cotton and porcine skin layers, stratum corneum, viable epidermis, and dermis) was validated and applied in in vitro porcine skin penetration/retention studies. This study proposes, for the first time, a method for assaying TTN in separated porcine skin layers (stratum corneum, viable epidermis, and dermis). The skin studies were carried out using tape stripping and cutaneous retention techniques. The procedures for the extraction of TTN from dermatological formulations (creams and gels) and biological and non-biological matrices used with the tape stripping and retention techniques were also evaluated. The LC method consisted of a mobile phase composed of a mixture of methanol, water, and glacial acetic acid (85:15:1, v/v); a C18 column used as the stationary phase; a flow rate of 1.0 mL min−1; an injection volume of 100 μL; and TTN detection at 342 nm. The method was linear in the range of 0.05–15.00 μg mL−1 (r = 0.9999), and it was precise and accurate. The limit of detection (LOD) and limit of quantification (LOQ) were 0.0165 μg mL−1 and 0.0495 μg mL−1, respectively. TTN was extracted from different matrices, showing good precision [relative standard deviation (RSD) of <5%] and accuracy (89.4–113.9%). This method was successfully applied in the evaluation of TTN skin retention/permeation from dermatological formulations (cream and gel). A higher penetration of TTN through the skin was achieved with the gel rather than the cream, showing the influence of the dosage form. Therefore, the developed method can easily be applied in porcine skin penetration/retention studies of dermatological formulations containing TTN, and it is able to discriminate the behaviours of the different formulations.

Harnessing nanotechnology for enhanced topical delivery of clindamycin phosphate

The treatment of acne warrants development of formulation aiming to enhance topical delivery with minimum systemic absorption. The aim of present study was to develop, optimize and characterize clindamycin phosphate-loaded nanostructured lipid carriers (CP-NLC) gel for enhanced topical delivery. CP-NLC was prepared using melt emulsification comibined with sonication technique using oleic acid (liquid lipid), precirol ATO5 (solid lipid), and tween 80 (surfactant). The optimized formulation attained using Box-Behnken statistical design exhibited particle size of 136 ± 0.11 nm, narrow PDI (0.256 ± 0.10), and high entrapment efficiency and high drug loading. TEM and SEM studies confirmed the spherical nature of the particles. Further, CP-NLC was loaded into Carbopol®940 gel and 1% concentration was evaluated for in vitro studies. The drug release from CP-NLC gel was 1.5-fold greater than from marketed formulation Clindac A®. The cumulative drug permeated through the skin was also found to be higher for CP-NLC gel (1.6-fold) than Clindac A® gel. The skin retention study, tape stripping technique and confocal laser scanning microscopy demonstrated enhanced skin retention and depth of permeation for CP-NLC gel. Therefore, formulating NLC for topical delivery of CP will render many benefits over marketed formulation thus proving as a promising carrier in the treatment of acne.

Advancement through epidermis using tape stripping technique and Reflectance Confocal Microscopy

The tape stripping technique is increasingly used in research regarding skin barrier function. However, number of tape strips varies between studies, and literature considering advancement into stratum corneum/epidermis in relation to number of tape strips is scarce. The aim of this pilot study was to assess the advancement through epidermis using tape stripping technique in healthy volunteers. A total of ten healthy volunteers were included. From all volunteers 0, 5, 15 and 35 consecutive tape strips (D-squame) were taken from four adjacent skin areas on the middle volar forearm, followed by Reflectance Confocal Microscopy (RCM) of the four areas to assess epidermal thickness. Squame Scan was used to determine amount of protein removed. Stratum corneum was completely removed in all volunteers after 35 tape strips. Advancement into epidermis was predominantly achieved by the first 15 tape strips, removing 25% of the total epidermis, whereas 35 tape strips removed 33% of epidermis. Protein removal per tape decreased with increasing depth. Information on advancement into the epidermis according to number of tape strips taken, is a significant step forward. The possibility to obtain samples from different layers of epidermis may lead to an improved understanding of skin barrier properties.

Onychomycosis Caused by Malassezia pachydermatis in a Dog

Background: Malassezia species are commensal skin organisms of warm-blooded vertebrates that can act as opportunistic pathogens. Malassezia pachydermatis is of importance in both veterinary and human medicine. Recognised initially as causes of infection of the skin, they are now known to be superficial commensals as well as potential causes of infections in domestic animals and more serious human conditions such as fungemia. They have also been implicated in the pathogenesis of allergic and other inflammatory diseases. Onychomycosis is defined as fungal infection of the claw (nail disease) caused by dermatophytes (Microsporum and Trichophyton genus), non-dermatophyte molds (hyaline and dematiaceous) and/or yeasts. The objective of this work was to report a case of canine onychomycosis by Malassezia pachydermatis based on reference standard diagnostics of this pathology.Case: A 9-year-old male West Highland White Terrier presented history of claw abnormality: brown staining and partly brittle. The dog has no apparent history of trauma on the affected claw and no skin disease was reported. Direct examination of claw was performed using the tape strip technique revealed Malassezia organisms. Nail fragments were cultured onto Sabouraud Dextrose Agar with Chloramphenicol and Cycloheximide. After 10 days of incubation (32ºC) nail fragments allowed the isolation of pure colonies of Malassezia pachydermatis. The histopathological evaluation was performed by Sector of Veterinary Clinical Pathology, Faculdade de Veterinária (FAVET/UFRGS) and fungal infection due to Malassezia pachydermatis was confirmed by histopathologic examination (Hematoxylin and eosin and Grocott’s methenamine silver stain) of the nail, that revealed abundant yeasts (blastoconidia).Discussion: Fungal infection of the skin, hair and nails are common and are primary caused by the dermatophyte molds. Non-dermatophyte molds isolated from nails constitute a long list, but only a few species cause onychomycoses. These include Scopulariopsis brevicaulis, Fusarium sp., Acremonium spp., Aspergillus spp., Penicillium spp. Yeasts like Malassezia and Candida spp. are saprophytes and usually represent incidental contaminants associated with a non-sterile specimen at mycological culture, however in some cases they may parasite the nails and become an etiological agent of the disease. M. pachydermatis, normally present on the skin and in the ear canal of dogs and cats, can act as opportunistic pathogenic microbe and frequently causes dermatitis and otitis in mammals. In the case of onychomycosis, there is little evidence that Malassezia yeasts are implicated in nail plate invasion, although this may be a rare occurrence. All species of the genus are obligatory lipid-dependent forms, with the exception of M. pachydermatis, as well as absence of keratinolytic ability. Malassezia organisms were commonly retrieved from the subungual claw fold region of normal healthy dogs (should be considered resident microflora of the normal canine claw fold). Some authors suggests that high numbers of yeast can be detected on cytological evaluation of the skin surface of the canine claw fold from allergic dogs in both the absence and presence of concurrent signs of pruritus and paronychia.

ENHANCING THE SUNSCREEN EFFICACY OF BEMOTRIZINOL MICROPIGMENT BY USING O/W NANOEMULSION TOPICAL PREPARATIONS

Objective: Bemotrizinol (BEMT) is the most efficient broad-spectrum UV-absorber having a dual mechanism of action in absorbing and reflecting photons. The main objective of this work was to develop successful oil in water (o/w) nanoemulsion for improving the solubility of BEMT and its protective characteristics.&#x0D; Methods: Pseudo-ternary phase diagrams were constructed using labrafac PG and isopropyl myristate as oil phase, tween 80 as surfactant (S) and cremophor EL as cosurfactant (CoS) the ratio of S/CoS was determined according to highest percent of water incorporation to the system. Full factorial study design (24) using Design-Expert® software was adopted to study the effect of four independent variables namely: oil type, oil concentration, S/CoSmix (3:1) concentrations and BEMT concentration on the particle size and the in vitro release at 2 h (Q2h) of the prepared nanoemulsion formulae. Two systems each of eight formulae were developed and evaluated through droplet size analysis, zeta potential measurement, refractive index, in vitro drug release and according to the desirability value two formulae (F6 and F14) were used for further evaluations including in vitro sun protection factor (SPF), ex-vivo deposition by tape stripping technique, permeation test and photostability study.&#x0D; Results: Formula (F14) was chosen as the optimum formula having an in vitro SPF of 16.08±0.39, lowest permeation of 140±0.06 μg/cm2after six h and highest photostability (t90% = 168.02) after 120 min.&#x0D; Conclusion: Despite the poor solubility of bemotrizinol, it could be enhanced by novel drug delivery systems with good SPF value while maintaining its photostability.

Caffeic acid skin absorption: Delivery of microparticles to hair follicles

Caffeic acid (CA) is a polyphenol that can be found in a wide range of vegetal dietary sources. It presents a remarkable antioxidant potential, but what is more interesting from the therapeutic point of view is, that it has demonstrated in vitro antimicrobial properties. Folliculitis is a common skin condition, usually caused by a bacterial or fungal infection, in which hair follicles become inflamed. A typical challenge in dermal application when the actives diffuse passively through the skin in a quick manner, as it is the case of CA, is to provide the effective concentration of the compound at the target site for the sufficient time to finalize the treatment adequately and reduce the possibility to trigger systemic side effects. To achieve this goal, it is necessary to appropriately design the drug delivery system. In this case, we leverage the ability of microparticles to accumulate into the hair follicles to design O/W-emulsions containing CA-loaded controlled-release microparticles. Two different emulsion types containing CA were prepared, one containing free CA and the other containing microencapsulated CA. Traditional and differential tape stripping techniques were performed to investigate drug distribution within the different skin layers and into the hair follicles. The Tape stripping results demonstrated that the tapes S3-S5 and S6-S10 presented a higher total amount of CA. The strips are collected and extracted in groups to assure the extraction of quantifiable amounts of drug. Samples S11-15 and S16-20 show a decrease in the amount of quantified CA, as it was expected. Thus, it can be seen that the amount of active decreases while the stratum corneum depth increases. The retention studies demonstrated that, the microparticles tend to produce a more homogeneous distribution of CA, within the stratum corneum and a higher retention into the hair follicle, which can be attributed to their size and uniformity. Besides, MPs present an additional advantage because they guarantee a continuous release of CA in the target for a prolonged period, allowing the treatment of folliculitis with a single dose until the MPs are removed from the hair follicle by its natural regeneration process or particle depletion of CA.

In vivo Human Skin Penetration of the UV Filter Ethylhexyl Triazone: Effect of Lipid Microparticle Encapsulation

Background/Aims: The data available on the skin permeability of ethylhexyl triazone (EHT), a widely used high-molecular-weight (823.1-Da) UV filter, are scarce and obtained only via in vitro studies. Therefore, we evaluated in vivo the penetration of EHT in human stratum corneum by the tape stripping technique. Moreover, the effect of EHT encapsulation in lipid microparticles (LMs) on its diffusion through the stratum corneum was examined. Methods: LMs loaded with EHT were prepared using glyceryl behenate and phosphatidylcholine. Creams containing EHT free or encapsulated in LMs in conjunction with the two most commonly used UV filters, octyl methoxycinnamate (OMC) and butyl methoxydibenzoylmethane (BMDBM), were applied to human volunteers and the fraction of the applied sunscreen dose having penetrated into different stratum corneum layers was measured. Results and Conclusion: For the cream with the nonencapsulated sunscreen agent, the percentage of the applied EHT dose diffused into the stratum corneum was 21.9 ± 4.9%, not significantly different from that of the smaller-molecular-weight OMC (22.2 ± 7.6%) and BMDBM (20.5 ± 3.7%). A marked (45.7%) and statistically significant reduction in the in vivo skin penetration of EHT was attained with the cream containing microencapsulated EHT. The decreased percutaneous penetration provided by the LMs should favor the efficacy of EHT and limit potential toxicological risks.

Oleic Acid Nanovesicles of Minoxidil for Enhanced Follicular Delivery.

Current topical minoxidil (MXD) formulations involve an unpleasant organic solvent which causes patient incompliance in addition to side effects in some cases. Therefore, the objective of this work was to develop an MXD formulation providing enhanced follicular delivery and reduced side effects. Oleic acid, being a safer material, was utilized to prepare the nanovesicles, which were characterized for size, entrapment efficiency, polydispersity index (PDI), zeta potential, and morphology. The nanovesicles were incorporated into the emugel Sepineo® P 600 (2% w/v) to provide better longer contact time with the scalp and improve physical stability. The formulation was evaluated for in vitro drug release, ex vivo drug permeation, and drug deposition studies. Follicular deposition of the vesicles was also evaluated using a differential tape stripping technique and elucidated using confocal microscopy. The optimum oleic acid vesicles measured particle size was 317 ± 4 nm, with high entrapment efficiency (69.08 ± 3.07%), narrow PDI (0.203 ± 0.01), and a negative zeta potential of −13.97 ± 0.451. The in vitro drug release showed the sustained release of MXD from vesicular gel. The skin permeation and deposition studies revealed superiority of the prepared MXD vesicular gel (0.2%) in terms of MXD deposition in the stratum corneum (SC) and remaining skin over MXD lotion (2%), with enhancement ratios of 3.0 and 4.0, respectively. The follicular deposition of MXD was 10-fold higher for vesicular gel than the control. Confocal microscopy also confirmed the higher absorption of rhodamine via vesicular gel into hair follicles as compared to the control. Overall, the current findings demonstrate the potential of oleic acid vesicles for effective targeted skin and follicular delivery of MXD.