Novel mechanisms and devices to enable successful transdermal drug delivery

Investigating the Free Volumes as Nanospaces in Human Stratum Corneum Lipid Bilayers Using Positron Annihilation Lifetime Spectroscopy (PALS)

This work is the first one that provides not only evidence for the existence of free volumes in the human stratum corneum but also focuses on comparing these experimental data, obtained through the unique positron annihilation lifetime spectroscopy (PALS) method, with theoretical values published in earlier works. The mean free volume of 0.269 nm was slightly lower than the theoretical value of 0.4 nm. The lifetime τ3 (1.83 ns with a coefficient of variation CV of 3.21%) is dependent on the size of open sites in the skin. This information was used to calculate the free volume radius R (0.269 nm with CV 2.14%), free volume size Vf (0.081 nm3 with CV 4.69%), and the intensity I3 (9.01% with CV 10.94%) to estimate the relative fractional free volume fv (1.32 a.u. with CV 13.68%) in human skin ex vivo. The relation between the lifetime of o-Ps (τ3) and the radius of free volume (R) was formulated using the Tao-Eldrup model, which assumes spherical voids and applies to sites with radii smaller than 1 nm. The results indicate that PALS is a powerful tool for confirming the existence of free volumes and determining their size. The studies also focused on describing the probable locations of these nanospaces in SC lipid bilayers. According to the theory, these play an essential role in dynamic processes in biological systems, including the diffusion of low-molecular-weight hydrophobic and moderately hydrophilic molecules. The mechanism of their formation has been determined by the molecular dynamics of the lipid chains.

Dissolvable microneedles in the skin: Determination the impact of barrier disruption and dry skin on dissolution

Dissolvable microneedles (DMNs), fabricated from biocompatible materials that dissolve in both water and skin have gained popularity in dermatology. However, limited research exists on their application in compromised skin conditions. This study compares the hyaluronic acid-based DMNs penetration, formation of microchannels, dissolution, and diffusion kinetics in intact, barrier-disrupted (tape stripped), and dry (acetone-treated) porcine ear skin ex vivo. After DMNs application, comprehensive investigations including dermoscopy, stereomicroscope, skin hydration, transepidermal water loss (TEWL), optical coherence tomography (OCT), reflectance confocal laser scanning microscopy (RCLSM), confocal Raman micro-spectroscopy (CRM), two-photon tomography combined with fluorescence lifetime imaging (TPT-FLIM), histology, and scanning electron microscopy (SEM) were conducted. The 400 µm long DMNs successfully penetrated the skin to depths of ≈200 µm for dry skin and ≈200-290 µm for barrier-disrupted skin. Although DMNs fully inserted into all skin conditions, their dissolution rates were high in barrier-disrupted and low in dry skin, as observed through stereomicroscopy and TPT-FLIM. The dissolved polymer exhibited a more significant expansion in barrier-disrupted skin compared to intact skin, with the smallest increase observed in dry skin. Elevated TEWL and reduced skin hydration levels were evident in barrier-disrupted and dry skins compared to intact skin. OCT and RCLSM revealed noticeable skin indentation and pronounced microchannel areas, particularly in barrier-disrupted and dry skin. Additional confirmation of DMN effects on the skin and substance dissolution was obtained through histology, SEM, and CRM techniques. This study highlights the impact of skin condition on DMN effectiveness, emphasizing the importance of considering dissolvability and dissolution rates of needle materials, primarily composed of hyaluronic acid, for optimizing DMN-based drug delivery.

Application of the Born Model to Describe Salt Partitioning in Hydrated Polymers

The classic Born model can be used to predict salt partitioning properties observed in hydrated polymers, but there are often significant quantitative discrepancies between these predictions and the experimental data. Here, we use an updated version of the Born model, reformulated to account for the local environment and mesh size of a hydrated polymer, to describe previously published NaCl, KCl, and LiCl partitioning properties of model cross-linked poly(ethylene glycol) diacrylate polymers. This reformulated Born model describes the influence of polymer structure (i.e., network mesh size and its relationship with water content) and external salt concentration on salt partitioning in the polymers with a significant improvement relative to the classic Born model. The updated model most effectively describes NaCl partitioning properties and provides an additional fundamental understanding of salt partitioning processes, for NaCl, KCl, and LiCl, in hydrated polymers that are of interest for a variety of environmental and biological applications.

Revolutionizing transdermal drug delivery: unveiling the potential of cubosomes and ethosomes

The area of drug delivery systems has witnessed significant advancements in recent years, with a particular focus on improving efficacy, stability, and patient compliance. Transdermal drug delivery offers numerous benefits compared to conventional methods of drug administration through the skin. It helps in avoiding gastric irritation, hepatic first-pass metabolism, and gastric degradation of the drug. It bypasses the gastrointestinal tract, eliminating the risk of first-pass metabolism and allowing drugs to be administered without being affected by pH, enzymes, or intestinal bacteria. Additionally, it allows for sustained release of the drug, is noninvasive, and enhances patient adherence to the treatment regimen. The transdermal drug delivery system (TDDS) can serve as an alternative route for drug administration in individuals who cannot tolerate oral medications, experience nausea, or are unconscious. When compared to intravenous, hypodermic, and other parenteral routes, TDDS stands out due to its ability to eliminate pain, reduce the risk of infection, and prevent disease transmission associated with needle reuse. Consequently, the overall patient compliance is significantly improved with the utilization of TDDS. Among the noteworthy developments are cubosomes and ethosomes, two distinct yet promising carriers that have garnered attention for their unique properties. In conclusion, this review synthesizes the current knowledge on cubosomes and ethosomes, shedding light on their individual strengths and potential synergies. The exploration of their application in various therapeutic areas underscores their versatility and establishes them as key players in the evolving landscape of drug delivery systems.

Transdermal Delivery of Niacin Through Polysaccharide Films Ameliorates Cutaneous Flushing in Experimental Wistar Rats

BACKGROUND

Niacin, an established therapeutic for dyslipidemia, is hindered by its propensity to induce significant cutaneous flushing when administered orally in its unmodified state, thereby constraining its clinical utility.

OBJECTIVE

This study aimed to fabricate, characterize, and assess the in-vitro and in-vivo effectiveness of niacin-loaded polymeric films (NLPFs) comprised of carboxymethyl tamarind seed polysaccharide. The primary objective was to mitigate the flushing-related side effects associated with oral niacin administration.

METHODS

NLPFs were synthesized using the solvent casting method and subsequently subjected to characterization, including assessments of tensile strength, moisture uptake, thickness, and folding endurance. Surface characteristics were analyzed using a surface profiler and scanning electron microscopy (SEM). Potential interactions between niacin and the polysaccharide core were investigated through X-ray diffraction experiments (XRD) and Fourier transform infrared spectroscopy (FTIR). The viscoelastic properties of the films were explored using a Rheometer. In-vitro assessments included drug release studies, swelling behavior assays, and antioxidant assays. In-vivo efficacy was evaluated through skin permeation assays, skin irritation assays, and histopathological analyses.

RESULTS

NLPFs exhibited a smooth texture with favorable tensile strength and moisture absorption capabilities. Niacin demonstrated interaction with the polysaccharide core, rendering the films amorphous. The films displayed slow and sustained drug release, exceptional antioxidant properties, optimal swelling behavior, and viscoelastic characteristics. Furthermore, the films exhibited biocompatibility and non-toxicity towards skin cells.

CONCLUSION

NLPFs emerged as promising carrier systems for the therapeutic transdermal delivery of niacin, effectively mitigating its flushing-associated adverse effects.

Tailoring of Bilosomal Nanogel for Augmenting the Off-Label Use of Sildenafil Citrate in Pediatric Pulmonary Hypertension

Pediatric pulmonary hypertension is a serious syndrome with significant morbidity and mortality. Sildenafil is widely used off-label in pediatric patients with pulmonary arterial hypertension. In this study, bile salt-stabilized nanovesicles (bilosomes) were screened for their efficacy to enhance the transdermal delivery of the phosphodiesterase type 5 inhibitor, sildenafil citrate, in an attempt to augment its therapeutic efficacy in pediatric pulmonary hypertension. A response surface methodology was implemented for fabricating and optimizing a bilosomal formulation of sildenafil (SDF-BS). The optimized SDF-BS formulation was characterized in terms of its entrapment efficiency (EE), zeta potential, vesicle size, and in vitro release profile. The optimized formula was then loaded onto hydroxypropyl methyl cellulose (HPMC) hydrogel and assessed for skin permeation, in vivo pharmacokinetics, and pharmacodynamic studies. The optimized SDF-BS showed the following characteristic features; EE of 88.7 ± 1.1%, vesicle size of 185.0 + 9.2 nm, zeta potential of -20.4 ± 1.1 mV, and efficiently sustained SDF release for 12 h. Skin permeation study revealed a remarkable improvement in SDF penetration from bilosomal gel compared to plain SDF gel. In addition, pharmacokinetic results revealed that encapsulating SDF within bilosomal vesicles significantly enhanced its systemic bioavailability (∼3 folds), compared to SDF oral suspension. In addition, pharmacodynamic investigation revealed that, compared to plain SDF gel or oral drug suspension, SDF-BS gel applied topically triggered a significant elevation (p < 0.05) in cGMP serum levels, underscoring the superior therapeutic efficacy of SDF-BS gel. Conclusively, bilosomes can be viewed as a promising nanocarrier for transdermal delivery of SDF that would grant higher therapeutic efficiency while alleviating the limitations encountered with SDF oral administration.

Permeation-Enhancing Strategies for Transdermal Delivery of Cannabinoids

Introduction: This review aims to provide an overview of the advancements and status of clinical studies and potential permeation-enhancing strategies in the transdermal delivery of cannabinoids. Methods: A systematic and comprehensive literature search across academic databases, search engines, and online sources to identify relevant literature on the transdermal administration of cannabinoids. Results: Cannabinoids have proven beneficial in the treatment of wide-ranging physical and psychological disorders. A shift toward legalized cannabinoid products has increased both interests in cannabinoid research and the development of novel medicinal exploitations of cannabinoids in recent years. Oral and pulmonary delivery of cannabinoids has several limitations, including poor bioavailability, low solubility, and potential side effects. This has diverted scientific attention toward the transdermal route, successfully overcoming these hurdles by providing higher bioavailability, safety, and patient compliance. Yet, due to the barrier properties of the skin and the lipophilic nature of cannabinoids, there is a need to increase the permeation of the drugs to the underneath layers of skin to reach desired therapeutic plasma levels. Literature describing detailed clinical trials on cannabinoid transdermal delivery, either with or without permeation-enhancing strategies, is limited. Conclusion: The limited number of reports indicates that increased attention is needed on developing and examining efficient transdermal delivery systems for cannabinoids, including patch design and composition, drug-patch interaction, clinical effectiveness and safety in vivo, and permeation-enhancing strategies.

Advancements in Skin-Mediated Drug Delivery: Mechanisms, Techniques, and Applications

Skin-mediated drug delivery methods currently are receiving significant attention as a promising approach for the enhanced delivery of drugs through the skin. Skin-mediated drug delivery offers the potential to overcome the limitations of traditional drug delivery methods, including oral administration and intravenous injection. The challenges associated with drug permeation through layers of skin, which act as a major barrier, are explored, and strategies to overcome these limitations are discussed in detail. This review categorizes skin-mediated drug delivery methods based on the means of increasing drug permeation, and it provides a comprehensive overview of the mechanisms and techniques associated with these methods. In addition, recent advancements in the application of skin-mediated drug delivery are presented. The review also outlines the limitations of ongoing research and suggests future perspectives of studies regarding the skin-mediated delivery of drugs.

Electrospun Nanofibers Encapsulated with Natural Products: A Novel Strategy to Counteract Skin Aging

The skin is the primary tissue affected by wounds and aging, significantly impacting its protective function. Natural products are widely used in cosmetics, representing a new approach to preventing age-related damage. Nanomedicine combines nanotechnology and traditional treatments to create innovative drugs. The main targets of nanotechnological approaches are wound healing, regeneration, and rejuvenation of skin tissue. The skin barrier is not easily permeable, and the creation of modern nanodevices is a way to improve the passive penetration of substances. In this study, Helichrysum italicum oil (HO) was combined with different types of electrospun nanofibers to study their protective activity on the skin and to evaluate their future application for topical treatments. In the present research, we used biodegradable polymers, including polyvinyl alcohol (PVA) and polyvinylpyrrolidone (PVP), which were characterized by a scanning electron microscope (SEM). All results show a positive trend in cell proliferation and viability of human skin stem cells (SSCs) and BJ fibroblasts pre-treated with combined nanofibers and then exposed to UV stress. Gene expression analysis revealed the activation of a molecular rejuvenation program in SSCs treated with functionalized nanofibers before UV exposure. Understanding the mechanisms involved in skin changes during aging allows for the future application of nanomaterials combined with HO directly to the patients.

Deformable Vesicles with Edge Activators for the Transdermal Delivery of Non-Psychoactive Cannabinoids

BACKGROUND

Transdermal delivery of highly lipophilic molecules is challenging due to the strong barrier function of the skin. Vesicles with penetration enhancers are safe and efficient systems that could improve the transdermal delivery of non-psychoactive cannabinoids such as cannabidiol and desoxy-cannabidiol. In the last decades, research interest in desoxy-cannabidiol as a potent drug with anti-nociceptive properties has risen. Still, its scarce market availability poses a limit for both research and clinical applications. Therefore, it is necessary to improve the synthesis to produce sufficient amounts of desoxy-cannabidiol. Moreover, also the formulation aspects for this drug are challenging and require to be addressed to meet an efficient delivery to the patients.

OBJECTIVE

This work aimed to develop innovative phospholipid-based vesicles with propylene glycol (PG), oleic acid (OA), or limonene as edge activators, for the transdermal delivery of highly lipophilic drugs such as non-psychoactive cannabinoids. In particular, desoxy-cannabidiol was selected thanks to its anti-nociceptive activity, and its synthesis was improved enhancing the stereoselectivity of its synthon's production.

METHODS

Desoxy-cannabidiol was synthesized by Lewis acid-mediated condensation of p-mentha-2,8-dien- 1-ol and m-pentylphenol, improving the stereoselectivity of the first synthon's production. Transethosomes containing 20-50% w/w PG, 0.4-0.8% w/w OA, or 0.1-1% w/w limonene were optimized and loaded with cannabidiol or desoxy-cannabidiol (0.07-0.8% w/w, 0.6-7.0 mg/mL). Ex-vivo studies were performed to assess both the skin permeation and accumulation of the cannabinoids, as well as the penetration depth of fluorescein- loaded systems used as models.

RESULTS

An enantioselective bromination was added to the pathway, thus raising the production yield of pmentha- 2,8-dien-1-ol to 81% against 35%, and the overall yield of desoxy-cannabidiol synthesis from 12% to 48%. Optimized transethosomes containing 0.6 mg/mL cannabinoids were prepared with 1:10 PG:lipid weight ratio, 0.54 OA:lipid molar ratio, and 0.3 limonene:lipid molar ratio, showing good nanometric size (208 ± 20.8 nm - 321 ± 26.3 nm) and entrapment efficiency (> 80%). Ex-vivo tests showed both improved skin permeation rates of cannabinoids (up to 21.32 ± 4.27 μg/cm2 cannabidiol), and skin penetration (depth of fluorescein up to 240 μm, with PG).

CONCLUSION

Desoxy-cannabidiol was successfully produced at high yields, and formulated into transethosomes optimized for transdermal delivery. Loaded vesicles showed improved skin penetration of desoxy-cannabidiol, cannabidiol and a lipophilic probe. These results suggest the potential of these carriers for the transdermal delivery of highly lipophilic drugs.

Therapeutic Effects of Statins: Promising Drug for Topical and Transdermal Administration

Statins are HMG-CoA reductase inhibitors and decrease plasma low-density lipoprotein cholesterol (LDL-C) levels. They are well tolerated, and because of their LDL-C-lowering effect, they are utilized to decrease the risk of atherosclerosis and cardiovascular disease. However, statins have pleiotropic effects, including immunomodulatory, anti-inflammatory, antioxidant, and anticancer. Currently, oral administration is the only Food and Drug Administration (FDA)-approved route of administration for statins. However, other administration routes have demonstrated promising results in different pre-clinical and clinical studies. For instance, statins also seem beneficial in dermatitis, psoriasis, vitiligo, hirsutism, uremic pruritus, and graft-versus-host disease. Topically applied statins have been studied to treat seborrhea, acne, rhinophyma, and rosacea. They also have beneficial effects in contact dermatitis and wound healing in animal studies, (HIV) infection, osseointegration, porokeratosis, and some ophthalmologic diseases. Topical and transdermal application of statins is a non-invasive drug administration method that has shown significant results in bypassing the first-pass metabolism in the liver, thereby reducing possible adverse effects. This study reviews the multifaceted molecular and cellular impacts of statins, their topical and transdermal application, novel delivery systems, such as nanosystems for topical and transdermal administration and the challenges concerning this approach.

Transdermal drug delivery via microneedles for musculoskeletal systems

As the population is ageing and lifestyle is changing, the prevalence of musculoskeletal (MSK) disorders is gradually increasing with each passing year, posing a serious threat to the health and quality of the public, especially the elderly. However, currently prevalent treatments for MSK disorders, mainly administered orally and by injection, are not targeted to the specific lesion, resulting in low efficacy along with a series of local and systemic adverse effects. Microneedle (MN) patches loaded with micron-sized needle array, combining the advantages of oral administration and local injection, have become a potentially novel strategy for the administration and treatment of MSK diseases. In this review, we briefly introduce the basics of MNs and focus on the main characteristics of the MSK systems and various types of MN-based transdermal drug delivery (TDD) systems. We emphasize the progress and broad applications of MN-based transdermal drug delivery (TDD) for MSK systems, including osteoporosis, nutritional rickets and some other typical types of arthritis and muscular damage, and in closing summarize the future prospects and challenges of MNs application.

New Insights in Topical Drug Delivery for Skin Disorders: From a Nanotechnological Perspective

Skin, the largest organ in humans, is an efficient route for the delivery of drugs as it circumvents several disadvantages of the oral and parenteral routes. These advantages of skin have fascinated researchers in recent decades. Drug delivery via a topical route includes moving the drug from a topical product to a locally targeted region with dermal circulation throughout the body and deeper tissues. Still, due to the skin's barrier function, delivery through the skin can be difficult. Drug delivery to the skin using conventional formulations with micronized active components, for instance, lotions, gels, ointments, and creams, results in poor penetration. The use of nanoparticulate carriers is one of the promising strategies, as it provides efficient delivery of drugs through the skin and overcomes the disadvantage of traditional formulations. Nanoformulations with smaller particle sizes contribute to improved permeability of therapeutic agents, targeting, stability, and retention, making nanoformulations ideal for drug delivery through a topical route. Achieving sustained release and preserving a localized effect utilizing nanocarriers can result in the effective treatment of numerous infections or skin disorders. This article aims to evaluate and discuss the most recent developments of nanocarriers as therapeutic agent vehicles for skin conditions with patent technology and a market overview that will give future directions for research. As topical drug delivery systems have shown great preclinical results for skin problems, for future research directions, we anticipate including in-depth studies of nanocarrier behavior in various customized treatments to take into account the phenotypic variability of the disease.

Characterization of piroctone olamine for topical delivery to the skin

OBJECTIVE

Dandruff and its more severe related condition, seborrheic dermatitis affects a high proportion of the population at some point in their life. Piroctone olamine, also known as Octopirox® (OPX) is the monoethanolamine salt of piroctone and is an antifungal agent widely used for the management of dandruff. The aim of the present work was to characterize the physicochemical properties of piroctone olamine and to conduct pre-formulation studies for the development of novel topical formulations of this active.

METHODS

An HPLC method was developed and validated for the analysis of OPX. The melting point was determined using the DSC Q2000 (TA Instruments, USA). The distribution coefficient (logD(O/PBS) ) and partition coefficient (log Po/w ) was determined in phosphate-buffered saline (PBS) AND deionized (DI) water using the shake flask method. All experiments were performed at room temperature. The solubility was determined experimentally by adding amount of active to a solvent. The samples were kept at 32° ± 1°C for 48 h in a water bath. The stability of the compound was determined in a range of solvents by preparing solutions of 1 mg mL-1 in the relevant solvents. These solutions were kept and stirred throughout the experiment at 32 ± 1°C, and aliquots were taken at 24, 48 and 96 h.

RESULTS

The HPLC method was developed successfully; however, samples at the lower end of the calibration curve showed lower degrees of precision and accuracy. Based on experiments with DSC, the melting point was observed at an onset temperature of 132.4°C. The LogD was determined to be 1.84. The compound had the highest solubility in methanol (278.4 mg mL-1 ) and propylene glycol (PG), with a value of 248.8 mg mL-1 . The lowest solubility for OPX was in dimethyl isosorbide (9.9 mg mL-1 ), Labrafac™ (3.6 mg mL-1 ) and isostearyl isostearate (0.5 mg mL-1 ). Over the 4 days, OPX showed stability in ethanol and PG, while a notable decrease in OPX was observed in PBS and DI water at 32 ± 1°C.

CONCLUSION

The physicochemical properties of OPX were characterized to find suitable excipients able to target the epidermis for topical delivery. Building on these findings, future work will focus on the development of novel topical formulation of OPX.

A Conformable Ultrasound Patch for Cavitation-Enhanced Transdermal Cosmeceutical Delivery

Increased consumer interest in healthy-looking skin demands a safe and effective method to increase transdermal absorption of innovative therapeutic cosmeceuticals. However, permeation of small-molecule drugs is limited by the innate barrier function of the stratum corneum. Here, a conformable ultrasound patch (cUSP) that enhances transdermal transport of niacinamide by inducing intermediate-frequency sonophoresis in the fluid coupling medium between the patch and the skin is reported. The cUSP consists of piezoelectric transducers embedded in a soft elastomer to create localized cavitation pockets (0.8 cm² , 1 mm deep) over larger areas of conformal contact (20 cm² ). Multiphysics simulation models, acoustic spectrum analysis, and high-speed videography are used to characterize transducer deflection, acoustic pressure fields, and resulting cavitation bubble dynamics in the coupling medium. The final system demonstrates a 26.2-fold enhancement in niacinamide transport in a porcine model in vitro with a 10 min ultrasound application, demonstrating the suitability of the device for short-exposure, large-area application of sonophoresis for patients and consumers suffering from skin conditions and premature skin aging.

Hybrid Dissolving Microneedle-Mediated Delivery of Ibuprofen: Solubilization, Fabrication, and Characterization

Microneedles have recently emerged as a promising platform for delivering therapeutic agents by disrupting the skin, resulting in improved and high drug delivery via this route. Ibuprofen is widely used topically and orally for chronic pain conditions; to avoid untoward gastric effects, topical application is preferred over the oral route. This study aimed to enhance the solubility of the poorly water-soluble ibuprofen using Soluplus (SP) as a solubilizer and to fabricate dissolving microneedle patches of the drug. The fabricated patches were compared with marketed oral and topical formulations of ibuprofen. A 432-fold increase was observed in the solubility of the drug at 8% SP. The FTIR studies revealed that the drug and polymers were compatible. MNs were of uniform morphology and released the drug in a predictable manner. The in vivo analysis on healthy human volunteers revealed a Cmax of 28.7 µg/mL ± 0.5 with a T_max of 24 h and a MRT of 19.5 h, which was significantly higher than that observed for commercially available topical formulations. The prepared ibuprofen microneedles have higher bioavailability and MRT at a lower dose (165 µg) as compared to tablet and cream doses (200 mg).

Exploring new frontiers in drug delivery with minimally invasive microneedles: fabrication techniques, biomedical applications and regulatory aspects

INTRODUCTION

Transdermal drug delivery is limited by the stratum corneum, inhibiting the therapeutic potential of the permeants. Microneedles (MN) have opened new frontiers in transdermal drug delivery systems. These micro-sized needles offer painless and accentuated delivery of drugs even with high molecular weights.

AREAS COVERED

The review embodies drug delivery strategies with microneedles with a description of MN types and fabrication techniques using various materials. The application of MN is not limited to drug delivery, but it also encompasses in vaccine delivery, diagnosis, phlebotomy and even in the cosmetic industry. The review also tabulates microneedle-based marketed formulations. In a nutshell, we aim to present a panoramic view of microneedles including the design, applications, and regulatory aspects of MN.

EXPERT OPINION

With the availability of numerous materials at the disposal of pharmaceutical scientists; the microneedle-based drug delivery technology has offered significant interventions towards the management of chronic maladies including cardiovascular disorders, diabetes, asthma, mental depression, etc. As happens with any new technology there are concerns with MN also such as biocompatibility issues with the material used for the fabrication. Nevertheless, the pharmaceutical industry must strive for preparing harmless, efficient, and cost-effective MN based delivery systems for wider acceptance and patient compliance.

Combination of Cellulose Derivatives and Chitosan-Based Polymers to Investigate the Effect of Permeation Enhancers Added to In Situ Nasal Gels for the Controlled Release of Loratadine and Chlorpheniramine

The purpose of the study is to develop and assess mucoadhesive in situ nasal gel formulations of loratadine and chlorpheniramine maleate to advance the bioavailability of the drug as compared to its conventional dosage forms. The influence of various permeation enhancers, such as EDTA (0.2% w/v), sodium taurocholate (0.5% w/v), oleic acid (5% w/v), and Pluronic F 127 (10% w/v), on the nasal absorption of loratadine and chlorpheniramine from in situ nasal gels containing different polymeric combinations, such as hydroxypropyl methylcellulose, Carbopol 934, sodium carboxymethylcellulose, and chitosan, is studied. Among these permeation enhancers, sodium taurocholate, Pluronic F127 and oleic acid produced a noticeable increase in the loratadine in situ nasal gel flux compared with in situ nasal gels without permeation enhancer. However, EDTA increased the flux slightly, and in most cases, the increase was insignificant. However, in the case of chlorpheniramine maleate in situ nasal gels, the permeation enhancer oleic acid only showed a noticeable increase in flux. Sodium taurocholate and oleic acid seems to be a better and efficient enhancer, enhancing the flux > 5-fold compared with in situ nasal gels without permeation enhancer in loratadine in situ nasal gels. Pluronic F127 also showed a better permeation, increasing the effect by >2-fold in loratadine in situ nasal gels. In chlorpheniramine maleate in situ nasal gels with EDTA, sodium taurocholate and Pluronic F127 were equally effective, enhancing chlorpheniramine maleate permeation. Oleic acid has a better effect as permeation enhancer in chlorpheniramine maleate in situ nasal gels and showed a maximum permeation enhancement of >2-fold.

The novel treatments based on tissue engineering, cell therapy and nanotechnology for cutaneous leishmaniasis

Cutaneous leishmaniasis (CL) is a global public health issue. Conventional treatments have substantial costs, side effects, and parasite resistance. Due to easy application and inexpensive cost, topical treatment is the optimal approach for CL. It could be used alone or with systemic treatments. Electrospun fibers as drug release systems in treating skin lesions have various advantages such as adjustable drug release rate, maintaining appropriate humidity and temperature, gas exchange, plasticity at the lesion site, similarity with the skin extracellular matrix (ECM) and drug delivery with high efficiency. Hydrogels are valuable scaffolds in the treatment of skin lesions. The important features of hydrogels include preserving unstable drugs from degradation, absorption of wound secretions, high biocompatibility, improving the re-epithelialization of the wound and preventing the formation of scars. One of the issues in local drug delivery systems for the skin is the low permeability of drugs in the skin. Polymeric scaffolds that are designed as microneedle patches can penetrate the skin and overcome this challenge. Also, drug delivery using nanocarriers increases the effectiveness of drugs in lower and more tolerable doses and reduces the toxicity of drugs. The application of cell therapy in the treatment of parasitic and infectious diseases has been widely investigated. The complexity of leishmaniasis treatment requires identifying new treatment options like cell therapy to overcome the disease. Topics investigated in this study include drug delivery systems based on tissue engineering scaffolds, nanotechnology and cell therapy-based studies to reduce the complications of CL.

Transethosomes: A Promising Challenge for Topical Delivery Short Title: Transethosomes for Topical Delivery

Skin provides an excellent barrier to molecular transport, as the stratum corneum is the most formidable barrier to the passage of most pharmaceuticals. Various attempts have been made to improve drug administration into the body through intact skin. Though very few routes are as attractive as the topical route, drug transport through the skin is challenging. To overcome the challenges, researchers have found a system in which the drug is encapsulated into the vesicle, penetrating deeper into the skin to hit the target site. Vesicular systems like transethosome, an ultra- deformable vesicle (UDV), tend to accumulate in the skin layers. Since transethosomes have small particle size and can easily alter the shape of vesicles compared to other vesicular systems, they can penetrate through the layers of skin. Hence, the drug encapsulated into transethosomes can easily reach the target site. Transethosomes consist of ethanol and phospholipids along with an edge activator. Ethanol and edge activator help to enhance the skin permeation of transethosomes. Various methods of preparation of transethosomes, comparison of transethosomes with other lipid vesicles, characterization of transethosomes, and application of transethosomes have been covered in this review. Transethosomes can deliver a different variety of drugs, such as anticancer, corticosteroids, proteins and peptides, analgesics.

A thermodynamic and kinetic analysis of human epidermal penetration of phenolic compounds: II. Maximum flux and solute diffusion through stratum corneum lipids

Warming the skin is a key means of promoting solute permeation through the skin. Changes in solute permeation associated with variations in skin temperature also assist in understanding the mechanism by which solutes permeate the skin. However, few studies have considered the relative impact of temperature on the main determinants of the maximum flux for a solute across the skin, the solubility of a solute and its diffusivity in the stratum corneum. In this study, we quantified for the first time the thermodynamics associated with the maximum skin fluxes for a series of phenolic compounds of similar size but with varying lipophilicity (defined by the logarithms of their octanol/water partition coefficient, logP). These studies were undertaken using aqueous donor solutions (along with testosterone as a reference solute) across human epidermal membranes in vertical Franz diffusion cells at 4 °C, 24 °C and 37 °C with intermittent receptor sampling and volume replacement over 24 h. Kinetic and thermodynamic analyses included the estimation of the stratum corneum (SC) apparent SC diffusivity from the SC maximum fluxes and SC solubilities and the associated activation energies, enthalpies and entropies for diffusion. The key findings were that the differences in the maximum flux of phenolic compounds varying in lipophilicity mainly arose from differences in SC solubility at the various temperatures and that, at the highest temperature, SC permeability and SC diffusion were affected by SC lipid fluidisation and that variations in SC - water partitioning enthalpies explain some of the previously low activation energies for permeation of the more lipophilic phenols. Higher enthalpies for diffusion were seen for solutes with addition hydrogen bonding capacity and the highest negative entropy was observed with the more compact solutes. Various relationships between the derived thermodynamic parameters were explored and interpreted in a proposed model for solute partitioning into and permeation through the SC intercellular lipid lamellae.

Development and Evaluation of Topical Ethosomal Gel for Fungal Infections

BACKGROUND

Fungal infections are one of the most common dermatological issues worldwide. Candida species-caused fungal infections are frequent on the cutaneous surface. Eberconazole (EBZ) has the strongest antifungal action against Candida spp., the major source of fungal infections.

METHOD

In the present study, the cold method followed by probe sonication was used to create EBZ-loaded ethosomal dispersion. The solubility of ethosomes in different lipids and surfactants was used to choose these components. Under magnetic stirring, the dispersion was absorbed into a carbopol 934 gel. In vitro antifungal activity was performed using the Agar well diffusion method, and their topical effectiveness against pathogenic Candida albicans was compared to that of a marketed formulation containing EBZ.

RESULTS

Eberconazol incorporated into gel displayed sustained release in an in vitro release assay. Based on the zone of inhibition diameters, EBZ formulation was determined to be efficient against C. albicans when compared to the commercialized cream and plain gel.

CONCLUSION

Based on these findings, the current study found that EBZ possesses significant antifungal efficacy against C. albicans.

Transethosomal Gel for the Topical Delivery of Celecoxib: Formulation and Estimation of Skin Cancer Progression

The topical delivery of therapeutics is a promising strategy for managing skin conditions. Cyclooxygenase-2 (COX-2) inhibitors showed a possible target for chemoprevention and cancer management. Celecoxib (CXB) is a selective COX-2 inhibitor that impedes cell growth and generates apoptosis in different cell tumors. Herein, an investigation proceeded to explore the usefulness of nano lipid vesicles (transethosomes) (TES) of CXB to permit penetration of considerable quantities of the drug for curing skin cancer. The prepared nanovesicles were distinguished for drug encapsulation efficiency, vesicle size, PDI, surface charge, and morphology. In addition, FT-IR and DSC analyses were also conducted to examine the influence of vesicle components. The optimized formulation was dispersed in various hydrogel bases. Furthermore, in vitro CXB release and ex vivo permeability studies were evaluated. A cytotoxicity study proceeded using A431 and BJ1 cell lines. The expression alteration of the cyclin-dependent kinase inhibitor 2A (CDKN2A) gene and DNA damage and fragmentation using qRT-PCR and comet assays were also investigated. Optimized CXB-TES formulation was spherically shaped and displayed a vesicle size of 75.9 ± 11.4 nm, a surface charge of -44.7 ± 1.52 mV, and an entrapment efficiency of 88.8 ± 7.2%. The formulated TES-based hydrogel displayed a sustained in vitro CXB release pattern for 24 h with an enhanced flux and permeation across rat skin compared with the control (free drug-loaded hydrogel). Interestingly, CXB-TES hydrogel has a lower cytotoxic effect on normal skin cells compared with TES suspension and CXB powder. Moreover, the level of expression of the CDKN2A gene was significantly (p ≤ 0.01, ANOVA/Tukey) decreased in skin tumor cell lines compared with normal skin cell lines, indicating that TES are the suitable carrier for topical delivery of CXB to the cancer cells suppressing their progression. In addition, apoptosis demonstrated by comet and DNA fragmentation assays was evident in skin cancer cells exposed to CXB-loaded TES hydrogel formulation. In conclusion, our results illustrate that CXB-TES-loaded hydrogel could be considered a promising carrier and effective chemotherapeutic agent for the management of skin carcinoma.

Natural polysaccharide-based biodegradable polymeric platforms for transdermal drug delivery system: a critical analysis

Natural biodegradable polymers generally include polysaccharides (starch, alginate, chitin/chitosan, hyaluronic acid derivatives, etc.) and proteins (collagen, gelatin, fibrin, etc.). In transdermal drug delivery systems (TDDS), these polymers play a vital role in controlling the device's drug release. It is possible that natural polymers can be used for TDDS to attain predetermined drug delivery rates due to their physicochemical properties. These polymers can be employed to market products and scale production because they are readily available and inexpensive. As a result of these polymers, new pharmaceutical delivery systems can be developed that is both regulated and targeted. The focus of this article is the application of a biodegradable polymeric platform based on natural polymers for TDDS. Due to their biocompatibility and biodegradability, natural biodegradable polymers are frequently used in biomedical applications. Additionally, these natural biodegradable polymers are being studied for their characteristics and behaviors.

Deep Eutectic Systems as Novel Vehicles for Assisting Drug Transdermal Delivery

In recent years, deep eutectic systems (DES) emerged as novel vehicles for facilitating the transdermal delivery of various drugs, including polysaccharides, proteins, insulin, vaccine, nanoparticles, and herb extracts. The objective of this study is to conduct a comprehensive review of the application of DES to transdermal drug delivery, based on previous work and the reported references. Following a brief overview, the roles of DES in TDDS, the modes of action, as well as the structure-activity relationship of DES are discussed. Particularly, the skin permeation of active macromolecules and rigid nanoparticles, which are the defining characteristics of DES, are extensively discussed. The objective is to provide a comprehensive understanding of the current investigation and development of DES-based transdermal delivery systems, as well as a framework for the construction of novel DES-TDDS in the future.

Localized topical drug delivery systems for skin cancer: Current approaches and future prospects

Topical drug delivery presents a novel substitute to the conventional drug-distribution routes of oral delivery and injection. Apart from the simplicity and non-invasiveness, the skin also serves as a “reservoir” that sustains administration over a period of days. Nanocarriers provide new potential for the treatment of skin disease. The skin’s barrier function offers a considerable obstacle for the potential nanocarriers to infiltrate into the tissue. However, the barrier is partially weakened in case of damage or inflammation, as in the case of skin cancer. Nanoparticles may promote the penetration of the skin. Extensive research has been done into producing nanoparticles for topical distribution; nevertheless, relatively little progress has been achieved in transferring them to the clinic for treating skin malignancies. The prior art features the critical concepts of skin malignancies and techniques in current clinical care. The present review gives a complete viewpoint of the numerous nanoparticle technologies studied for the topical treatment of skin malignancies and outlines the hurdles that hamper its advancement from the bench to the bedside. The review also intends to give knowledge of the routes that control nanoparticle penetration into the skin and their interactions inside the tissue.

Trilayer dissolving polymeric microneedle array loading Rose Bengal transfersomes as a novel adjuvant in early-stage cutaneous melanoma management

Melanoma remains a global concern, but current therapies present critical limitations pointing out the urgent need for novel strategies. Among these, the cutaneous delivery of drugs selectively damaging cancer cells is highly attractive. Rose Bengal (RB) is a dye exhibiting selective cytotoxicity towards melanoma, but the high water solubility and low permeability hinder its therapeutic potential. We previously developed RB-loaded transfersomes (RBTF) to mediate the RB dermal delivery; however, a platform efficiently delivering RBTF in the deepest strata is essential for a successful therapeutic activity. In this regard, dissolving microneedles release the encapsulated cargo up to the dermis, painlessly piercing the outmost skin layers. Therefore, herein we developed and characterised a trilayer dissolving microneedle array (RBTF-TDMNs) loading RBTF to maximise RBTF intradermal delivery in melanoma management. RBTF-TDMNs were proven strong enough to pierce excised porcine skin and rapidly dissolve and deposit RBTF intradermally while maintaining their physicochemical properties. Also, 3D visualisation of the system itself and while penetrating the skin was performed by multi-photon microscopy. Finally, a dermatokinetic study showed that RBTF-TDMNs offered unique delivery efficiency advantages compared to RBTF dispersion and free drug-loaded TDMNs. The proposed RBTF-TDMNs represent a valuable potential adjuvant tool for the topical management of melanoma.

Effects of Lipid Shape and Interactions on the Conformation, Dynamics, and Curvature of Ultrasound-Responsive Liposomes

We perform coarse-grained molecular dynamics simulations of bilayers composed of various lipids and cholesterol at their different ratios. Simulations show that cholesterol-lipid interactions restrict the lateral dynamics of bilayers but also promote bilayer curvature, indicating that these opposite effects simultaneously occur and thus cannot significantly influence bilayer stability. In contrast, lyso-lipids effectively pack the vacancy in the bilayer composed of cone-shaped lipids and thus reduce bilayer dynamics and curvature, showing that bilayers are more significantly stabilized by lyso-lipids than by cholesterol, in agreement with experiments. In particular, the bilayer composed of cone-shaped lipids shows higher dynamics and curvature than does the bilayer composed of cylindrical-shaped lipids. To mimic ultrasound, a high external pressure was applied in the direction of bilayer normal, showing the formation of small pores that are surrounded by hydrophilic lipid headgroups, which can allow the release of drug molecules encapsulated into the liposome. These findings help to explain experimental observations regarding that liposomes are more significantly stabilized by lyso-lipids than by cholesterol, and that the liposome with cone-shaped lipids more effectively releases drug molecules upon applying ultrasound than does the liposome with cylindrical-shaped lipids.

A Mathematical Approach Using Strat-M® to Predict the Percutaneous Absorption of Chemicals under Finite Dose Conditions

Estimation of the percutaneous absorption is essential for the safety assessment of cosmetic and dermopharmaceutical products. Currently, an artificial membrane, Strat-M^®, has been focused on as the tool which could obtain the permeation parameters close to the skin-derived values. Nevertheless, few practical methodologies using the permeation parameters for assessing percutaneous absorption under in-use conditions are available. In the present study, based on Fick's first law of diffusion, a novel mathematical model incorporating the permeation parameters as well as considering the water evaporation (T_eva) was constructed. Then, to evaluate the applicability domain of our model in the case where Strat-M^®-derived parameters were used, the permeation parameters were compared between the skin from edible porcine and Strat-M^®. Regarding chemicals (-0.2 ≤ Log K_ow ≤ 2.0), their permeation profiles were equivalent between Strat-M^® and porcine skin. Therefore, for these chemicals, the percutaneous absorption was calculated using our model with the permeation parameters obtained using Strat-M^® and the T_eva determined by measuring the solution weight. The calculated values revealed a good correlation to the values obtained using porcine skin in finite dose experiments, suggesting that our mathematical approach with Strat-M^® would be useful for the future safety assessment of cosmetic and dermopharmaceutical products.

Adapting Clofazimine for Treatment of Cutaneous Tuberculosis by Using Self-Double-Emulsifying Drug Delivery Systems

Although chemotherapeutic treatment regimens are currently available, and considerable effort has been lavished on the development of new drugs for the treatment of tuberculosis (TB), the disease remains deeply intractable and widespread. This is due not only to the nature of the life cycle and extraordinarily disseminated habitat of the causative pathogen, principally Mycobacterium tuberculosis (Mtb), in humans and the multi-drug resistance of Mtb to current drugs, but especially also to the difficulty of enabling universal treatment of individuals, immunocompromised or otherwise, in widely differing socio-economic environments. For the purpose of globally eliminating TB by 2035, the World Health Organization (WHO) introduced the "End-TB" initiative by employing interventions focusing on high impact, integrated and patient-centered approaches, such as individualized therapy. However, the extraordinary shortfall in stipulated aims, for example in actual treatment and in TB preventative treatments during the period 2018-2022, latterly and greatly exacerbated by the COVID-19 pandemic, means that even greater pressure is now placed on enhancing our scientific understanding of the disease, repurposing or repositioning old drugs and developing new drugs as well as evolving innovative treatment methods. In the specific context of multidrug resistant Mtb, it is furthermore noted that the incidence of extra-pulmonary TB (EPTB) has significantly increased. This review focusses on the potential of utilizing self-double-emulsifying drug delivery systems (SDEDDSs) as topical drug delivery systems for the dermal route of administration to aid in treatment of cutaneous TB (CTB) and other mycobacterial infections as a prelude to evaluating related systems for more effective treatment of CTB and other mycobacterial infections at large. As a starting point, we consider here the possibility of adapting the highly lipophilic riminophenazine clofazimine, with its potential for treatment of multi-drug resistant TB, for this purpose. Additionally, recently reported synergism achieved by adding clofazimine to first-line TB regimens signifies the need to consider clofazimine. Thus, the biological effects and pharmacology of clofazimine are reviewed. The potential of plant-based oils acting as emulsifiers, skin penetration enhancers as well as these materials behaving as anti-microbial components for transporting the incorporated drug are also discussed.

Framework Nucleic Acid Immune Adjuvant for Transdermal Delivery Based Chemo-immunotherapy for Malignant Melanoma Treatment

Despite the tremendous progresses of cancer immunotherapy, its current clinical responses rate in melanoma remains to be improved. Here, we have reported a skin penetrating tetrahedral framework nucleic acid immune adjuvant (FNAIA) to transdermally deliver chemotherapy drugs into melanoma to induce the immunogenic death of tumor cells and expose tumor antigens, which with assistance of CpG oligodeoxynucleotide incorporated in FNAIA could trigger systemic tumor-specific immune responses. Compared with free CpG, FNAIA could penetrate deeper into subcutaneous tumor tissues and more effectively stimulate dendritic cell maturation. Notably, doxorubicin-loaded FNAIA locally applied on the intact skin above the melanoma could effectively inhibit the growth of mouse B16F10 melanoma and increase tumor CD8+ T cell infiltration. Moreover, combined with immune checkpoint inhibitor, the growth of distant tumors could also be effectively inhibited, suggesting that this strategy could induce systemic immune responses. Therefore, this work provides a new idea for non-invasive treatment of skin cancer.

Development of Dapagliflozin Solid Lipid Nanoparticles as a Novel Carrier for Oral Delivery: Statistical Design, Optimization, In-Vitro and In-Vivo Characterization, and Evaluation

Controlling hyperglycemia and avoiding glucose reabsorption are significant goals in type 2 diabetes treatments. Among the numerous modes of medication administration, the oral route is the most common. Introduction: Dapagliflozin is an oral hypoglycemic agent and a powerful, competitive, reversible, highly selective, and orally active human SGLT2 inhibitor. Dapagliflozin-loaded solid lipid nanoparticles (SLNs) are the focus of our present investigation. Controlled-release lipid nanocarriers were formulated by integrating them into lipid nanocarriers. The nanoparticle size and lipid utilized for formulation help to regulate the release of pharmaceuticals over some time. Dapagliflozin-loaded nanoparticles were formulated by hot homogenization followed by ultra-sonication. The morphology and physicochemical properties of dapagliflozin-SLNs have been characterized using various techniques. The optimized dapagliflozin-SLNs have a particle size ranging from 100.13 ± 7.2 to 399.08 ± 2.4 nm with 68.26 ± 0.2 to 94.46 ± 0.7% entrapment efficiency (%EE). Dapagliflozin-SLNs were optimized using a three-factor, three-level Box–Behnken design (BBD). Polymer concentration (X1), surfactant concentration (X2), and stirring duration (X3) were chosen as independent factors, whereas %EE, cumulative drug release (%CDR), and particle size were selected as dependent variables. Interactions between drug substances and polymers were studied using Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). Differential scanning calorimetry (DSC), X-ray diffraction (XRD), and atomic force microscopy (AFM) analysis indicated the crystalline change from the drug to the amorphous crystal. Electron microscope studies revealed that the SLNs’ structure is nearly perfectly round. It is evident from the findings that dapagliflozin-SLNs could lower elevated blood glucose levels to normal in STZ-induced diabetic rats, demonstrating a better hypoglycemic impact on type 2 diabetic patients. The in vivo pharmacokinetic parameters of SLNs exhibited a significant rise in C_max (1258.37 ± 1.21 mcg/mL), AUC (5247.04 mcg/mL), and oral absorption (2-fold) of the drug compared to the marketed formulation in the Sprague Dawley rats.

Minoxidil Nanoparticles Targeting Hair Follicles Enhance Hair Growth in C57BL/6 Mice

We previously found that 1% minoxidil (MXD) nanoparticles prepared using a bead mill method led to an increase I n hair follicle delivery and hair growth in C57BL/6 mice. In the present study, we designed a nanoparticle formulation containing 5% MXD (MXD-NPs) using the bead mill method and investigated the hair-growth effect of MXD-NPs and a commercially available MXD solution (CA-MXD). Hair growth and in vivo permeation studies were conducted using C57BL/6 mice. Moreover, we examined the MXD contents in the upper (hair bulge) and the lower hair follicle (hair bulb) and observed the hair follicle epithelial stem cells (HFSC) by immunohistochemical staining using the CD200 antibody. The mean particle size of the MXD in the MXD-NPs was 139.8 nm ± 8.9 nm. The hair-growth effect of the MXD-NPs was higher than that of CA-MXD, and the MXD content in the hair bulge of mice treated with MXD-NPs was 7.4-fold that of the mice treated with CA-MXD. In addition, the activation of HFSC was observed around the bulge in the MXD-NPs-treated mice. We showed that MXD-NPs enable the accumulation of MXD in the upper hair follicles more efficiently than CA-MXD, leading the activation of HFSC and the hair growth.

The Anti-Inflammatory Effect of Humulus lupulus Extract In Vivo Depends on the Galenic System of the Topical Formulation

We demonstrated the anti-inflammatory and anti-oxidative effects of Humulus lupulus (HL) extract on solar simulator-irradiated primary human keratinocytes (PHKs) by analyzing ERK and p38 MAPK phosphorylation and production of IL-6 and IL-8. The anti-inflammatory effect of topically applied HL was further tested in vivo on human skin. To this end, we developed an oil-in-water (O/W) and a water-in-oil (W/O) cream with a lipid content of 40%. The anti-inflammatory effect of 1% HL extract incorporated in these two vehicles was assessed in a randomized, prospective, placebo controlled, double-blind UVB erythema study with 40 healthy volunteers. Hydrocortisone acetate (HCA) in the corresponding vehicle served as positive control. Surprisingly, both HL and HCA were only effective in the O/W system but not in the W/O formulation. Release studies using vertical diffusion cells (Franz cells) revealed that HCA was released in much higher amounts from the O/W cream compared to the W/O formulation. In summary, we have shown that 1% HL extract exerts anti-inflammatory effects comparable to 1% HCA, but only when incorporated in our O/W cream. Our findings confirm the critical role of the vehicle in topical anti-inflammatory systems.

Effect of Cosmetics Use on the In Vitro Skin Absorption of a Biocide, 1,2-Benzisothiazolin-3-one

1,2-Benzisothiazolin-3-one (BIT) is a commonly used organic biocide containing an isothiazolone ring. However, it may have adverse effects on human health and its risk needs to be properly evaluated. Dermal exposure is the main route of BIT exposure, and co-exposed substances may affect its absorption. The dermal permeation profile of BIT has not been well-studied. This study aimed to investigate the dermal permeation profiles of BIT with or without cosmetic use. Dermal permeation profiles of BIT were investigated after infinite- (100 μg/cm²), or a finite-dose (10 μg/cm²) application with or without cosmetics using a minipig skin and Strat-M^®, an artificial membrane. A cream, lotion, and essence (namely, face serum) were pre-treated as representative cosmetics on minipig skin for 30 min, with BIT treatment afterward. After the treatment, BIT left on the skin surface was collected by cotton swabbing, BIT in the stratum corneum, by sequential tape stripping, and BIT retained in the remaining skin was extracted after cutting the skin into pieces before LC-MS/MS analysis. When an infinite dose was applied, permeation coefficients (K_p, cm/h) for minipig skin and Strat-M^® were 2.63 × 10⁻³ and 19.94 × 10⁻³, respectively, reflecting that skin permeation was seven to eight times higher in Strat-M^® than in the minipig skin. BIT, in the presence of cosmetics, rapidly permeated the skin, while the amount in the stratum corneum and skin deposit was reduced. We performed a risk assessment of dermally applied BIT in the absence or presence of cosmetics by calculating the skin absorption rate at 10 h based on the toxicological data from several references. The risk level was higher in the presence of essence as compared to lotion, which was higher than cream, which was higher than the control (non-treated). However, all of the margins of safety values obtained were greater than 100, suggesting that BIT is safe for use in dermally exposed consumer products. We believe that this research contributes to a greater understanding of the risk assessment of isothiazolinone biocides.

In vitro percutaneous absorption studies of cannabidiol using human skin: Exploring the effect of drug concentration, chemical enhancers, and essential oils

Cannabidiol, a non-psychoactive constituent of cannabis, has garnered much attention after United States Food and Drug Administration approved Epidiolex® for oral use. Although therapeutic effect of cannabidiol after systemic absorption has been investigated extensively, its therapeutic potential in treating skin disorders after local delivery still needs further exploration. Our study has investigated the effect of cannabidiol concentration, chemical enhancers, and essential oils on percutaneous absorption of cannabidiol. In vitro permeation tests were conducted on human skin. The 24 h study results suggest no significant difference in amount of drug absorbed into skin, between 5% (242.41 ± 12.17 µg/cm²) and 10% (232.79 ± 20.82 cm²) cannabidiol solutions. However, 1% delivered (23.02 ± 4.74 µg/cm²) significantly lower amount of drug into skin than 5% and 10%. Transcutol and isopropyl myristate did not enhance delivery of cannabidiol. However, oleic acid was found to be useful as chemical enhancer. Oleic acid (43.07 ± 10.11 µg/cm²) had significantly higher cannabidiol delivery into skin than the group without oleic acid (10.98 ± 3.40 µg/cm²) after a 4 h in vitro permeation study. Essential oils at concentrations tested had lower total cannabidiol delivery when compared to control. This study's findings will help guide future research on the pharmacological effect of percutaneously delivered cannabidiol on inflammatory skin disorders.

Transdermal Enhancement Strategy of Lappaconitine: Alteration of Keratin Configuration by Counter-Ion

The objective of this study was to develop a lappaconitine (LA) transdermal patch with counter-ion to increase the transdermal permeability of the drug, and a theory of counter-ion altering the conformation of the skin keratin was put forward based on the in vitro skin permeation study and physicochemical properties of ion-pairs. Formulation factors including pressure sensitive adhesives (PSAs), drug-loading, counter-ions and molar ratios of counter-ion were screened by in vitro skin permeation study. The optimized formulation was composed of 7% LA, 1.5 mole cinnamic acid and AAOH (PSA containing hydroxyl group synthesized by our laboratory) as an adhesive matrix. The optimized patch was evaluated by the pharmacokinetic and analgesic pharmacodynamic studies. AUC_0-t and pain inhibition ratio of the optimized patch were 2450.40 ± 848.52 h ng/mL and 81.18%, which showed good absorption into the skin and excellent analgesic effect. The mechanism of facilitated transdermal drug permeation by counter-ion was investigated by ATR-FTIR, thermal analysis, FTIR, XPS and molecular docking. The results indicated that after the formation of ion-pairs, the excess counter-ions would alter the conformation of the skin keratin, thus increasing the transdermal penetration of LA. In conclusion, the LA patch was successfully optimized, and the effect of counter-ions on the skin was clarified at the molecular level. These findings provided additional references for the application of counter-ion in the transdermal drug delivery system.

Preparation and Evaluation of Polyvinylpyrrolidone Electrospun Nanofiber Patches of Pioglitazone for the Treatment of Atopic Dermatitis

Nanofibers have many promising biomedical applications. They can be used for designing transdermal and dermal drug delivery systems. This project aimed to prepare and characterize polyvinylpyrrolidone-based nanofibers as a dermal and transdermal drug delivery system using pioglitazone. Pioglitazone is an oral antidiabetic drug. In addition, it can act as an inflammatory process modulator, making it a good candidate for managing different skin inflammatory conditions such as atopic dermatitis, skin ulcers, and diabetic foot wound healing. Several nanofiber formulations were prepared using the electrospinning method at different drug loadings, polyvinylpyrrolidone concentrations, and flow rates. A cast film with the exact composition of selected nanofiber formulations was prepared as a control. Nanofibers were characterized using a scanning electron microscope to calculate the diameter. Fourier-transform infrared spectroscopy, differential scanning calorimetry, thermogravimetric analysis, and powder X-ray diffraction were performed for physical and biochemical characterizations. In vitro release, drug loading efficiency, and swelling studies were performed. Ex vivo permeation studies were performed using Franz diffusion cells with or without applying a solid microneedle roller. Round uniform nanofibers with a smooth surface were obtained. The diameter of nanofibers was affected by the drug loading and polymer concentration. Fourier-transform infrared spectra showed a potential physical interaction between the drug and the polymer. According to X-ray diffraction, pioglitazone existed in an amorphous form in prepared nanofibers, with partial crystallinity in the casted film. Nanofibers showed a higher swelling rate compared to the casted film. The drug dissolution rate for nanofibers was 2.3-folds higher than the casted films. The polymer concentration affected the drug dissolution rate for nanofibers; however, drug loading and flow rate did not affect the drug dissolution rate for nanofibers. The application of solid microneedles slightly enhances the total amount of drug permeation. However, it did not affect the flux of the drug through the separated epidermis layer for pioglitazone. The drug permeation flux in nanofibers was approximately five times higher than the flux of the casted film. It was observed that pioglitazone is highly retained in skin layers. Graphical abstract.

Carbopol 940 hydrogel containing curcumin-loaded micelles for skin delivery and application in inflammation treatment and wound healing

Inflammation and excessive reactive oxygen species production are main reason for slow wound healing, which needs an efficient therapy in clinic. In the paper, curcumin-enveloped methoxy poly(ethylene glycol)-poly(-valerolactone)-poly(-caprolactone) (MPEG-PVL-PCL) micelles...

Revisiting techniques to evaluate drug permeation through skin

INTRODUCTION

Investigating the transportation of a drug molecule through various layers of skin and determining the amount of drug retention in skin layers is of prime importance in transdermal and topical drug delivery. The information regarding drug permeation and retention in skin layers aids in optimizing a formulation and provides insight into the therapeutic efficacy of a formulation.

AREAS COVERED

This perspective covers various methods that have been explored to estimate drug/therapeutics in skin layers using in vitro, ex vivo, and in vivo conditions. In vitro methods such as diffusion techniques, ex vivo methods such as isolated perfused skin models and in vivo techniques including dermato-pharmacokinetics employing tape stripping, and microdialysis are discussed. Application of all techniques at various stages of formulation development where various local and systemic effects need to be considered.

EXPERT OPINION

The void in the existing methodologies necessitates improvement in the field of dermatologic research. Standardization of protocols, experimental setups, regulatory guidelines, and further research provides information to select an alternative for human skin to perform skin permeation experiments to increase the reliability of data generated through the available techniques. There is a need to utilize multiple techniques for appropriate dermato-pharmacokinetics evaluation and formulation's efficacy.

N-Alkylmorpholines: Potent Dermal and Transdermal Skin Permeation Enhancers

Transdermal drug delivery is an attractive non-invasive method offering numerous advantages over the conventional routes of administration. The main obstacle to drug transport is, however, the powerful skin barrier that needs to be modulated, for example, by transdermal permeation enhancers. Unfortunately, there are still only a few enhancers showing optimum properties including low toxicity and reversibility of enhancing effects. For this reason, we investigated a series of new N-alkylmorpholines with various side chains as potential enhancers in an in vitro permeation study, using three model permeants (theophylline, indomethacin, diclofenac). Moreover, electrical impedance, transepidermal water loss, cellular toxicity and infrared spectroscopy measurements were applied to assess the effect of enhancers on skin integrity, reversibility, toxicity and enhancers' mode of action, respectively. Our results showed a bell-shaped relationship between the enhancing activity and the hydrocarbon chain length of the N-alkylmorpholines, with the most efficient derivatives having 10-14 carbons for both transdermal and dermal delivery. These structures were even more potent than the unsaturated oleyl derivative. The best results were obtained for indomethacin, where particularly the C10-14 derivatives showed significantly stronger effects than the traditional enhancer Azone. Further experiments revealed reversibility in the enhancing effect, acceptable toxicity and a mode of action based predominantly on interactions with stratum corneum lipids.

Nanoemulsion-based dissolving microneedle arrays for enhanced intradermal and transdermal delivery

The development of dissolving microneedles (DMN) is one of the advanced technologies in transdermal drug delivery systems, which precisely deliver the drugs through a rapid dissolution of polymers after insertion into the skin. In this study, we fabricated nanoemulsion-loaded dissolving microneedle (DMN) arrays for intradermal and transdermal drug delivery. For this task, model drug (amphotericin B, AmB)-loaded nanoemulsion (NE) were prepared by the probe-sonication method. AmB-loaded-NE was prepared using Capmul MCM C-8 EP/NF, Tween^® 80, poly(vinyl alcohol) (PVA-10 kDa), and poly (vinyl pyrrolidone) (PVP-360 kDa or K29/32) by using SpeedMixer™, followed by probe-sonication and evaluated for particle size and polydispersity index (PDI). Transmission electron microscopy (TEM) was also used to assess the particle size before and after DMN casting. AmB-NE embedded DMN arrays were found to be strong enough, revealed efficient skin insertion, and penetrated down to the fourth layer (depth ≈ 508 μm) of Parafilm M^® (validated skin model). Ex vivo skin deposition experiments in full-thickness neonatal porcine demonstrated that after 24 h, AmB-NE-DMN arrays were able to deposit 111.05 ± 48.4 µg/patch AmB into the skin. At the same time, transdermal porcine skin permeation studies showed significantly higher permeability of AmB (29.60 ± 8.23 μg/patch) from AmB-NE-DMN compared to MN-free AmB-NE patches (5.0 ± 6.15 μg/patch) over 24 h. Antifungal studies of optimized AmB-NE-DMN, AmB-loaded discs and drug-free DMN against Candida albicans, confirmed the synergistic activity of Campul-MCM C-8, used in the nanoemulsion formulation. This study establishes that nanoemulsion based dissolving microneedle may serve as an efficient system for intradermal as well as transdermal drug delivery.

Microneedles in diagnostic, treatment and theranostics: An advancement in minimally-invasive delivery system

Microneedle (MN) technology plays an important role in biomedical engineering for their less intrusive access to the skin due to minimally or painless penetration, enhancement of drug permeability, improvement of detectability of biomolecules in the epidermal and dermal layers with therapeutic efficacy and safety. Furthermore, MNs possess some major disadvantages like difficulty in scale-up technique, variation in drug delivery pattern with respect to external environment of skin, blockage of arrays due to dermal tissues, induction of inflammation or allergy at the site of administration and restriction of dosing range based on the size of active. Additionally, microneedle acts as a transdermal theranostic device for monitoring the physiological parameters in clinical studies. The investigation of drug transfer mechanisms through microneedles includes coat and poke, poke and flow, poke and patch and poke and release method. This review article discusses different categories of microneedles with fabrication methods such as photolithography, laser cutting, 3D printing, etc. in therapeutic applications for treating cancer, diabetes, arthritis, obesity, neurological disorders, and glaucoma. Biosensing devices based on microneedles may detect target analytes directly in the interstitial fluid by penetrating the stratum corneum of the skin and thus microneedles-based devices can be considered as a single tool in diagnostic sensing and therapeutic administration of drugs inside the body. Moreover, the clinical status and commercial availability of microneedle devices are discussed in this review article to offer new insights to researchers and scientists. Continuous monitoring particularly for the determination of blood glucose concentration is one of the most important requirements for the development of next-generation healthcare devices. The aim of this review article focuses mainly on the theranostic applications of microneedles in various medical conditions such as malaria, glaucoma, cancer, etc.

Propolis - quality analysis and use in topical formulations

The aim of this study was to produce propolis extracts, assess their quality and effect on skin cells and determine the penetration of active ingredients from designed semi-solid topical formulations. The use of higher-concentration ethanol and a larger amount of raw material allows extracting a larger quantity of active ingredients from raw propolis. Ultrasound extraction is an effective method for the production of aqueous extracts of propolis. The results show that depending on concentration, propolis extracts reduce the viability of keratinocytes. The phenolic compounds under observation penetrated the epidermis and dermis from designed formulations. The base of semi-solid formulation influences the efficacy of propolis preparations. The overall quantity of phenolic compounds that penetrated the skin was around 2 % from the ointment and 1.5 % from the cream.

Vehicles for Drug Delivery and Cosmetic Moisturizers: Review and Comparison

Many dermatological conditions, such as eczema and psoriasis, are treated with topical therapeutic products. Instead of applying the active drug directly onto the skin, it is combined with a vehicle to aid in its delivery across the stratum corneum (SC) and into deeper regions of the skin, namely the epidermis and dermis. Absorption into the systemic circulation is minimized. Topical vehicles are also used as cosmetic moisturizers (often termed emollient therapy) to ameliorate dry skin, which is a cornerstone of the management of various dermatological conditions, including xerosis, eczema, psoriasis, and aging. The most common topical vehicles include ointments, creams, gels, and lotions, among others. It is crucial that topical vehicles are chosen based upon the size and properties (wet/dry, mucous/non-mucous, healthy/diseased) of the skin to be treated in order to optimize application and contact of the product with the skin, as this can have profound impacts on potency, efficacy, and patient compliance. This review examines common topical vehicles used for drug delivery and cosmetic moisturizers, including their formulation, advantages and disadvantages, and effects on the skin. The unique rules imposed by governing regulatory bodies in Australia and around the world, in terms of topical product claims, are also briefly examined.

Microemulsified Gel Formulations for Topical Delivery of Clotrimazole: Structural and In Vitro Evaluation

Microemulsified gels (μEGs) with fascinating functions have become indispensable as topical drug delivery systems due to their structural flexibility, high stability, and facile manufacturing process. Topical administration is an attractive alternative to traditional methods because of advantages such as noninvasive administration, bypassing first-pass metabolism, and improving patient compliance. In this article, we report on the new formulations of microemulsion-based gels suitable for topical pharmaceutical applications using biocompatible and ecological ingredients. For this, two biocompatible μE formulations comprising clove oil/Brij-35/water/ethanol (formulation A) and clove oil/Brij-35/water/1-propanol (formulation B) were developed to encapsulate and improve the load of an antimycotic drug, Clotrimazole (CTZ), and further gelatinized to control the release of CTZ through skin barriers. By delimiting the pseudo-ternary phase diagram, optimum μE formulations with clove oil (∼15%) and Brij-35 (∼30%) were developed, keeping constant surfactant/co-surfactant ratio (1:1), to upheld 2.0 wt % CTZ. The as-developed formulations were further converted into smart gels by adding 2.0 wt % carboxymethyl cellulose (CMC) as a cross-linker to adhere to the controlled release of CTZ through complex skin barriers. Electron micrographs show a fine, monodispersed collection of CTZ-μE nanodroplets (∼60 nm), which did not coalesce even after gelation, forming spherical CTZ-μEG (∼90 nm). However, the maturity of CTZ nanodroplets observed by dynamic light scattering suggests the affinity of CTZ for the nonpolar microenvironment, which was further supported by the peak-to-peak correlation of Fourier transform infrared (FTIR) analysis and fluorescence measurement. In addition, HPLC analysis showed that the in vitro permeation release of CTZ-μEG from rabbit skin in the ethanolic phosphate buffer (pH = 7.4) was significantly increased by >98% within 6.0 h. This indicates the sustained release of CTZ in μEBG and the improvement in transdermal therapeutic efficacy of CTZ over its traditional topical formulations.