In vitro study of ethosome penetration in human skin and hypertrophic scar tissue

Feeding the Body Through the Skin: Ethosomes and Transethosomes as a New Topical Delivery System for Bioactive Compounds

Because the feeding of our body through the oral route can be associated with many drawbacks due to the degradation of natural molecules during transit in the gastrointestinal tract, a transdermal delivery strategy, usually employed in the pharmaceutical field, can present an effective alternative for delivery of bioactives and nutrients from foods. In this review, the chance to feed the body with nutritive and bioactive molecules from food through transdermal administration is discussed. Various nanotechnological devices employed for topical and transdermal delivery of bioactive compounds are described. In addition, mechanisms underlying their potential use in the delivery of nutritive molecules, as well as their capability to efficaciously reach the dermis and promote systemic distribution, are detailed.

Tioconazole-Loaded Transethosomal Gel Using Box-Behnken Design for Topical Applications: In Vitro, In Vivo, and Molecular Docking Approaches

Tioconazole (TCZ) is a broad-spectrum fungicidal BCS class II drug with reported activity against Candida albicans, dermatophytes, and certain Staphylococci bacteria. We report the use of TCZ-loaded transethosomes (TEs) to overcome the skin's barrier function. TCZ-loaded TEs were fabricated by using a cold method with slight modification. Box-Behnken composite design was utilized to investigate the effect of independent variables. The fabricated TEs were assessed with various physicochemical characterizations. The optimized formulation of TCZ-loaded TEs was incorporated into gel and evaluated for pH, conductivity, drug content, spreadability, rheology, in vitro permeation, ex vivo permeation, and in vitro and in vivo antifungal activity. The fabricated TCZ-loaded TEs had a % EE of 60.56 to 86.13, with particle sizes ranging from 219.1 to 757.1 nm. The SEM images showed spherically shaped vesicles. The % drug permeation was between 77.01 and 92.03. The kinetic analysis of all release profiles followed Higuchi's diffusion model. The FTIR, DSC, and XRD analysis showed no significant chemical interactions between the drug and excipients. A significantly higher antifungal activity was observed for TCZ-loaded transethosomal gel in comparison to the control. The in vivo antifungal study on albino rats indicated that TCZ-loaded transethosomal gel showed a comparable therapeutic effect in comparison to the market brand Canesten®. Molecular docking demonstrated that the TCZ in the TE composition was surrounded by hydrophobic excipients with increased overall hydrophobicity and better permeation. Therefore, TCZ in the form of transethosomal gel can serve as an effective drug delivery system, having the ability to penetrate the skin and overcome the stratum corneum barrier with improved efficacy.

Exploring Nanocarriers as Treatment Modalities for Skin Cancer

Cancer is a progressive disease of multi-factorial origin that has risen worldwide, probably due to changes in lifestyle, food intake, and environmental changes as some of the reasons. Skin cancer can be classified into melanomas from melanocytes and nonmelanoma skin cancer (NMSC) from the epidermally-derived cell. Together it constitutes about 95% of skin cancer. Basal cell carcinoma (BCC) and cutaneous squamous cell carcinoma (CSCC) are creditworthy of 99% of NMSC due to the limited accessibility of conventional formulations in skin cancer cells of having multiple obstacles in treatment reply to this therapeutic regime. Despite this, it often encounters erratic bioavailability and absorption to the target. Nanoparticles developed through nanotechnology platforms could be the better topical skin cancer therapy option. To improve the topical delivery, the nano-sized delivery system is appropriate as it fuses with the cutaneous layer and fluidized membrane; thus, the deeper penetration of therapeutics could be possible to reach the target spot. This review briefly outlooks the various nanoparticle preparations, i.e., liposomes, niosomes, ethosomes, transferosomes, transethosomes, nanoemulsions, and nanoparticles technologies tested into skin cancer and impede their progress tend to concentrate in the skin layers. Nanocarriers have proved that they can considerably boost medication bioavailability, lowering the frequency of dosage and reducing the toxicity associated with high doses of the medication.

Numerical Optimization of Prednisolone-Tacrolimus Loaded Ultraflexible Transethosomes for Transdermal Delivery Enhancement; Box-Behnken Design, Evaluation, Optimization, and Pharmacokinetic Study

The aim of the present study is to formulate highly permeable carriers (i.e., transethosomes) for enhancing the delivery of prednisolone combined with tacrolimus for both topical and systemic pathological conditions. A Box-Behnken experimental design was implemented in this research. Three independent variables: surfactant concentration (X1), ethanol concentration (X2), and tacrolimus concentration (X3) were adopted in the design while three responses: entrapment efficiency (Y1), vesicle size (Y2), and zeta potential (Y3) were investigated. By applying design analysis, one optimum formulation was chosen to be incorporated into topical gel formulation. The optimized transethosomal gel formula was characterized in terms of pH, drug content, and spreadability. The gel formula was challenged in terms of its anti-inflammatory effect and pharmacokinetics against oral prednisolone suspension and topical prednisolone-tacrolimus gel. The optimized transethosomal gel achieved the highest rate of rat hind paw edema reduction (98.34%) and highest pharmacokinetics parameters (Cmax 133.266 ± 6.469 µg/mL; AUC_0-∞ 538.922 ± 49.052 µg·h/mL), which indicated better performance of the formulated gel.

Ethosomes and their monotonous effects on Skin cancer disruption

Skin cancer is one of the most prominent diseases, affecting all continents worldwide, and has shown a significant rise in mortality and prevalence. Conventional therapy, including chemotherapy and surgery, has a few drawbacks. The ethosomal systems would be thoroughly reviewed in this compilation, and they would be classified based on constituents: classical ethosomes, binary ethosomes, and transethosomes. Ethosomes systems are model lipid vesicular carriers with a substantial portion of ethanol. The impacts of ethosomal system components, preparation techniques, and their major roles in selecting the final characteristics of these nanocarriers are comprehensively reviewed in this chapter. The special techniques for ethosomes, including the cold approach, hot approach, injection method, mechanical dispersion method, and conventional method, are explained in this chapter. Various evaluation parameters of ethosomes were also explained. Furthermore, ethosomal gels, patches, and creams can be emphasised as innovative pharmaceutical drug formulations. Some hybrid ethosomal vesicles possessing combinatorial cancer therapy using nanomedicine could overcome the current drug resistance of specific cancer cells. Through the use of repurpose therapy, phytoconstituents may be delivered more effectively. A wide range of in vivo models are employed to assess their effectiveness. Ethosomes have provided numerous potential skin cancer therapeutic approaches in the future.

Ex Vivo Evaluation of Ethosomes and Transethosomes Applied on Human Skin: A Comparative Study

In this study, the transdermal fate of vesicular nanosystems was investigated. Particularly, ethosomes based on phosphatidylcholine 0.9% w/w and transethosomes based on phosphatidylcholine 0.9 or 2.7% w/w plus polysorbate 80 0.3% w/w as an edge activator were prepared and characterized. The vesicle mean size, morphology and deformability were influenced by both phosphatidylcholine and polysorbate 80. Indeed, the mean diameters of ethosome were around 200 nm, while transethosome's mean diameters were 146 or 350 nm in the case of phosphatidylcholine 0.9 or 2.7%, w/w, respectively. The highest deformability was achieved by transethosomes based on phosphatidylcholine 0.9%, w/w. The three types of vesicular nanosystems were applied on explanted human skin maintained in a bioreactor. Transmission electron microscopy demonstrated that all vesicles were able to enter the skin, keeping their structural integrity. Notably, the vesicle penetration capability was influenced by their physical-chemical features. Indeed, ethosomes reached keratinocytes and even the dermis, phosphatidylcholine 0.9% transethosomes were found in keratinocytes and phosphatidylcholine 2.7% transethosomes were found only in corneocytes of the outer layer. These findings open interesting perspectives for a differentiated application of these vesicles for transdermal drug delivery as a function of the cutaneous pathology to be addressed.

Formulation and Characterization of Metformin-Loaded Ethosomes for Topical Application to Experimentally Induced Skin Cancer in Mice

To achieve the best treatment of skin cancer, drug penetration inside the deepest layers of the skin is an important scientific interest. We designed an ethosome formulation that serves as a carrier for metformin and measured the in vitro skin permeation. We also aimed to measure the antitumor activity of the optimal ethosomal preparation when applied topically to chemically induced skin cancer in mice. We utilized a statistical Box-Behnken experimental design and applied three variables at three levels: lecithin concentration, cholesterol concentration and a mixture of ethanol and isopropyl alcohol concentrations. All formulations were prepared to calculate the entrapment efficiency %, zeta potential, size of the vesicles and drug release % after 1, 2, 4, 8 and 24 h. The size of the vesicles for the formulations was between 124 ± 14.2 nm and 560 ± 127 nm, while the entrapment efficiency was between 97.8 ± 0.23% and 99.4 ± 0.24%, and the drug release % after 8 h was between 38 ± 0.82% and 66 ± 0.52%. All formulations were introduced into the Box-Behnken software, which selected three formulations; then, one was assigned as an optimal formula. The in vivo antitumor activity of metformin-loaded ethosomal gel on skin cancer was greater than the antitumor activity of the gel preparation containing free metformin. Lower lecithin, high ethanol and isopropyl alcohol and moderate cholesterol contents improved the permeation rate. Overall, we can conclude that metformin-loaded ethosomes are a promising remedy for treating skin cancers, and more studies are warranted to approve this activity in other animal models of skin cancers.

A novel 5-Fluorocuracil multiple-nanoemulsion used for the enhancement of oral bioavailability in the treatment of colorectal cancer

5-Fluorouracil (5-FU) is a drug of choice for colorectal-cancer. But oral therapeutic efficacy of 5-FU is restricted due to their very little bioavailability because of poor membrane permeability and GIT-absorption. We have developed a multiple nanoemulsion (w/o/w i.e. 5-FU-MNE) in which 5-FU incorporated to improve their oral-absorption. Globule-size of opt-5-FU-MNE was 51.64 ± 2.61 nm with PDI and ZP 0.101 ± 0.001 and −5.59 ± 0.94, respectively. In vitro 5-FU-release and ex vivo permeation studies exhibited 99.71% release and 83.64% of 5-FU from opt-nanoformulation. Cytotoxic in vitro studies-exhibited that 5-FU in opt-5-FU-MNE was 5-times more potent than 5-FU-S on human-colon-cancer-cell-lines (HT-29). The enhanced C_max with AUC_0-8h with opt-5-FU-MNE was shown extremely significant (p < 0.001) in wistar rat’s plasma in the comparison of oral and i.v. treated group of 5-FU-S by PK-observations. Furthermore, opt-5-FU-MNE was showed much more significant (p < 0.001) results as compared to 5-FU-S (free) on cell lines for human colon cancer (HT-29).

Ultraflexible Liposome Nanocargo as a Dermal and Transdermal Drug Delivery System

A selected active pharmaceutical ingredient must be incorporated into a cargo carrier in a particular manner so that it achieves its goal. An amalgamation of active pharmaceutical ingredients (APIs) should be conducted in such a manner that it is simple, professional, and more beneficial. Lipids/polymers that are known to be used in nanocarriers for APIs can be transformed into a vesicular formulation, which offers elegant solutions to many problems. Phospholipids with other ingredients, such as ethanol and water, form suitable vesicular carriers for many drugs, overcoming many problems related to poor bioavailability, poor solubility, etc. Ultraflexible liposomes are novel carriers and new frontiers of drug delivery for transdermal systems. Auxiliary advances in vesicular carrier research have been made, enabling polymer-coated ethanolic liposomes to avoid detection by the body's immune system-specifically, the cells of the reticuloendothelial system. Ultraflexible liposomes act as a cargo system and a nanotherapeutic approach for the transport of therapeutic drugs and bioactive agents. Various applications of liposome derivatives in different diseases are emphasized in this review.

Lipid-Based Nanosystems as a Tool to Overcome Skin Barrier

Skin may be affected by many disorders that can be treated by topical applications of drugs on the action site. With the advent of nanotechnologies, new efficient delivery systems have been developed. Particularly, lipid-based nanosystems such as liposomes, ethosomes, transferosomes, solid lipid nanoparticles, nanostructured lipid carriers, cubosomes, and monoolein aqueous dispersions have been proposed for cutaneous application, reaching in some cases the market or clinical trials. This review aims to provide an overview of the different lipid-based nanosystems, focusing on their use for topical application. Particularly, biocompatible nanosystems able to dissolve lipophilic compounds and to control the release of carried drug, possibly reducing side effects, are described. Notably, the rationale to topically administer antioxidant molecules by lipid nanocarriers is described. Indeed, the structural similarity between the nanosystem lipid matrix and the skin lipids allows the achievement of a transdermal effect. Surely, more research is required to better understand the mechanism of interaction between lipid-based nanosystems and skin. However, this attempt to summarize and highlight the possibilities offered by lipid-based nanosystems could help the scientific community to take advantage of the benefits derived from this kind of nanosystem.

Soft Malleable Vesicles: versatile carriers for efficient topical delivery of fungal therapeutics

Fungal infections have become a subject of great concern and the incidence of fungal infections is increasing, presenting an enormous challenge to healthcare professionals. Since most of the fungal infections are occurring over the skin, the treatment option of these infections always involves topical application. However, in topical delivery drug reaches into systemic circulation through different barriers of skin. Nevertheless, due to the low permeability, skin restricts the movement of many drugs. Hence, a delivery system is required, which deliver the medicament into the skin layers or through the skin and into the systemic circulation. Ethosomes or Soft malleable vesicles are the novel lipid vesicular carrier that offer improved skin permeability and efficient delivery due to their structure and composition. They contain high concentration of ethanol, which increases the fluidity of the skin. Therefore, in the present paper, we have explored the utility of ethosomal systems in the topical treatment of fungal infections. Structure, compositions types, mechanism and techniques of preparation of ethosome also discussed in the paper.

Nanomedicines to Treat Skin Pathologies with Natural Molecules

The skin and mucous membranes are subjected to many disorders and pathological conditions. Nature offers a wide range of molecules with antioxidant activity able to neutralize, at least in part, the formation of free radicals and therefore to counteract the phenomena of cellular aging. Since synthetic drugs for the treatment of skin diseases can induce resistance, it is particularly interesting to use compounds of plant origin, transporting them in pharmaceutical forms capable of controlling their release and absorption. This review provides an overview of new findings about the use of lipid-based nanosystems for the delivery of natural molecules useful on the topical treatment of skin disorders. Several natural molecules encapsulated in lipid nanosystems have been considered in the treatment of some skin pathologies or diseases. Particularly, the use of rosemary and eucalyptus essential oil, saffron derivatives, curcumin, eugenol, capsaicin, thymol and lycopene has been reported. The molecules have been alternatively encapsulated in viscous systems, such as the organogels, or in liquid systems, such as ethosomes, transferosomes, solid lipid nanoparticles and monoolein based dispersions thickened by inclusion in carbomer gels. The nanostructured forms have been in vitro and in vivo investigated for the treatment of skin disorders due to dehydration, inflammation, melanoma, wound healing, fungal infections or psoriasis. The data reported in the different studies have suggested that the cutaneous application of lipid nanosystems allows a deep interaction between lipid matrix and skin strata, promoting a prolonged release and efficacy of the loaded natural molecules. This review suggests that the application of natural molecules onto the skin by lipid-based nanosystems can provide numerous clinician benefits in dermatology and cosmetics.

A comparative ex vivo permeation evaluation of a novel 5-Fluorocuracil nanoemulsion-gel by topically applied in the different excised rat, goat, and cow skin

AIM OF THE STUDY

5-Fluorouracil (5-FU) can't be given orally because of very low bioavailability and produces serious adverse effects. Therefore, the main objective of this research is to develop, evaluate, and comparative effects by different nanoformulations of topical application on chemoprevention of skin cancer in different types of skin.

MATERIAL AND METHODS

Castor oil (oil), Transcutol HP (surfactant), and Polyethylene glycol (PEG)-400 (co-surfactant) have taken on the basis of nonionic property and highest nanoemulsion (NE)-region. Aqueous micro titration method with ultra-sonication method (based on high energy) was used for the preparation of 5-FU-NE. Optimized-5-FU-NE was stable thermodynamically, and their characterizations was performed on the basis of globule size, zeta potential, refractive index, and viscosity. Optimized-NE has been converted into 5-FU-NE-Gel with the help of Carbopol® 934 and also performed their permeation studies in the different skins (cow, goat, and rat, ex vivo) using Logan transdermal diffusion cell (DHC-6T). Optimized-5-FU-NE and 5-FU-NE-Gel were evaluated cytotoxic studies (in vitro) on the melanoma cell lines.

RESULTS

The permeation of 5-FU from 5-FU-NE-Gel nanoformulation for rat skin model was 1.56 times higher than the 5-FU-NE and 12.51 times higher than the 5-FU-S for the cow and goat skin model. The values of steady state flux and permeability coefficient for 5-FU-NE-Gel of rat skin were higher i.e. 12.0244 ± 1.12 µgcm-2h-1 and 1.2024 ± 0.073 × 10-2 µg cm-2h-1, respectively. Optimized-5-FU-NE and 5-FU-NE-Gel nanoformulation were found to be physically stable. SK-MEL-5 cancer cells have showed the results based on cytotoxicity studies (in vitro) that 5-FU as Optimized-5-FU-NE-Gel is much more efficacious than 5-FU-NE followed by free 5-FU. Localization of 5-FU from 5-FU-NE-Gel was higher with higher permeation in rat skin.

CONCLUSION

5-FU-NE-Gel is found to be for the better to treatment of cutaneous malignancies. It can be developed 5-FU-NE-Gel could be a promising vehicle for the skin cancer chemoprevention.

Gelatin-Based Hydrogels for the Controlled Release of 5,6-Dihydroxyindole-2-Carboxylic Acid, a Melanin-Related Metabolite with Potent Antioxidant Activity

The ability of gelatin-based hydrogels of incorporating and releasing under controlled conditions 5,6-dihydroxyindole-2-carboxylic acid (DHICA), a melanin-related metabolite endowed with marked antioxidant properties was investigated. The methyl ester of DHICA, MeDHICA, was also tested in view of its higher stability, and different solubility profile. Three types of gelatin-based hydrogels were prepared: pristine porcine skin type A gelatin (HGel-A), a pristine gelatin cross-linked by amide coupling of lysines and glutamic/aspartic acids (HGel-B), and a gelatin/chitosan blend (HGel-C). HGel-B and HGel-C differed in the swelling behavior, showed satisfactorily high mechanical strength at physiological temperatures and well-defined morphology. The extent of incorporation into all the gelatins tested using a 10% w/w indole to gelatin ratio was very satisfactory ranging from 60 to 90% for either indoles. The kinetics of indole release under conditions of physiological relevance was evaluated up to 72 h. The highest values were obtained with HGel-B and HGel-C for MeDHICA (90% after 6 h), and an appreciable release was observed for DHICA reaching 30% and 40% at 6 h for HGel-B and HGel-C, respectively. At 72 h, DHICA and MeDHICA were released at around 30% from HGel-A at pH 7.4, with an increase up to 40% at pH 5.5 in the case of DHICA. DHICA incorporated into HGel-B proved fairly stable over 6 h whereas the free compound at the same concentration was almost completely oxidized. The antioxidant power of the indole loaded gelatins was monitored by chemical assays and proved unaltered even after prolonged storage in air, suggesting that the materials could be prepared in advance with respect to their use without alteration of their efficacy.

Ethosomal Gel for Improving Transdermal Delivery of Thymosin β-4

Purpose

Thymosin β-4(Tβ-4) is a macromolecular protein drug with potential for drug development in wound repair but is limited by the shortcomings of macromolecular protein, such as large volumes, poor membrane permeability, and unstable physicochemical characteristics. Ethosomes could enhance cell membrane fluidity and reduce epidermal membrane density to make macromolecular drugs through the stratum corneum into the deeper layers of the skin easily. Herein, we developed and characterized a novel transdermal delivery vehicle to load macromolecular protein peptides and use Tβ-4 as a model drug wrapped into ethosomes.

Methods

We used the orthogonal method to optimize the formulation of the ethosome preparation prepared by the ethonal infusion method. Ethosomal gels were characterized by using different analytical methods. Transdermal release rate in vitro have been demonstrated in Franz diffusion cells and the efficacy of drug-loaded nanocarriers in vivo was investigated in a mouse model.

Results

Optimized Tβ-4 ethosomal gels have good physicochemical properties. The drug amounts of the cumulative release in the ethosomal gel within 5 hours were 1.67 times that of the T-β4 gel in vitro release study, and the wound healing time of ethosomal gel group was only half of the T-β4 gel group in vivo pharmacokinetic study. Compared with the free drug group, the ethosome preparation not only promotes the percutaneous absorption process of the macromolecular protein drugs but also shortened wound recovery time.

Conclusion

Hence, we provide a possible good design for ethosomal gel system that can load macromolecular protein peptide drugs to achieve transdermal drug administration, promoting the percutaneous absorption of the drug and improving the effect.

Experimental Study of 5-fluorouracil Encapsulated Ethosomes Combined with CO2 Fractional Laser to Treat Hypertrophic Scar

OBJECTIVE

This study is designed to explore permeability of ethosomes encapsulated with 5-florouracil (5-FU) mediated by CO₂ fractional laser on hypertrophic scar tissues. Moreover, therapeutic and duration effect of CO₂ fractional laser combined with 5-FU encapsulated ethosomes in rabbit ear hypertrophic scar model will be evaluated.

METHODS

The permeated amount of 5-FU and retention contents of 5-FU were both determined by high-performance liquid chromatography (HPLC). Fluorescence intensities of ethosomes encapsulated with 5-FU (5E) labeled with Rodanmin 6GO (Rho) were measured by confocal laser scanning microscopy (CLSM). The permeability promotion of 5E labeled with Rho in rabbit ear hypertrophic scar mediated by CO₂ fractional laser was evaluated at 0 h, 6 h, 12 h, 24 h, 3 days and 7 days after the irradiation. The opening rates of the micro-channels were calculated according to CLSM. The therapeutic effect of 5EL was evaluated on rabbit ear hypertrophic scar in vivo. Relative thickness of rabbit ear hypertrophic scar before and after the treatment was measured by caliper method. Scar elevation index (SEI) of rabbit ear hypertrophic scar was measured using H&E staining.

RESULTS

The data showed that the penetration amount of 5EL group was higher than 5E group (4.15 ± 2.22 vs. 0.73 ± 0.33; p < 0.05) after 1-h treatment. Additionally, the penetration amount of 5EL was higher than that of the 5E group (107.61 ± 13.27 vs. 20.73 ± 3.77; p < 0.05) after 24-h treatment. The retention contents of the 5EL group also showed higher level than 5E group (24.42 ± 4.37 vs.12.25 ± 1.64; p < 0.05). The fluorescence intensity of Rho in hypertrophic scar tissues of the 5EL group was higher than that of the 5E group at different time points (1, 6, and 24 h). The opening rates of the micro-channels were decreased gradually within 24 h, and micro-channels were closed completely 3 days after the irradiation by CO₂ fractional laser. The relative thickness and SEI of rabbit ear hypertrophic scar after 7 days of treatment in the 5EL group were significantly lower than the 5E group.

CONCLUSION

CO₂ fractional laser combined with topical 5E can be effective in the treatment of hypertrophic scar in vivo and supply a novel therapy method for human hypertrophic scar.

Development and evaluation of finasteride loaded ethosomes for targeting to the pilosebaceous unit

Androgenetic alopecia, a major cause for baldness, is caused by the deposition of dihydrotestosterone (DHT) at the androgen receptors present in the pilosebaceous unit (PSU). Finasteride (FIN) is a potent 5α-reductase inhibitor capable of preventing the conversion of testosterone to DHT. But, its oral administration in males causes infertility. An attempt was made to prepare ethosomes of FIN with a size range 100-300 nm to enhance its delivery to the PSU. Finasteride loaded ethosomes (FES) were prepared using an ultra-probe sonicator and characterized for its size, morphology, surface charge and entrapment efficiency. The ability of FES to permeate across rat skin and frontal scalp skin of human cadaver was also evaluated. The spherical shaped ethosomes of different batches were in the size range of 107.8 ± 2.50 to 220.4 ± 6.92 nm and showed good permeation across rat skin and frontal scalp skin of human cadaver when compared to the unencapsulated FIN. The results portrayed the ability of FES to permeate across the stratum corneum to reach the PSU of the hair follicle. Although additional use of permeation enhancer increases the permeation of FIN across the skin, its addition may not be a favourable option for the deposition of ethosomes in the PSU.

5-Aminolevulinic acid loaded ethosomal vesicles with high entrapment efficiency for in vitro topical transdermal delivery and photodynamic therapy of hypertrophic scars

Photodynamic therapy (PDT) with 5-aminolevulinic acid (ALA) is an alternative therapy for hypertrophic scars (HS), which destroys human hypertrophic scar fibroblasts (HSF). However, the poor permeability of ALA both in HS tissue and HSF significantly restricts the PDT of HS. To overcome these barriers, ALA-loaded ethosomal vesicles (ALA-ES) were developed by a pH gradient active loading method and characterized by morphology, entrapment efficiency (EE) and stability. Results show that prepared ALA-ES are homogenous spherical lamellar vesicles, 53 ± 7 nm in size, 50.6 ± 2.3% in EE and have excellent stability. In vitro transdermal delivery studies through HS tissue were carried out by using Franz diffusion cells. Compared to the traditional ALA hydroalcoholic solution (ALA-HA), ALA-ES achieve higher drug retention in less administration time, and fluorescence microscopy showed that ALA-ES penetrate into the deeper dermis of HS in a shorter time, indicating that ALA-ES can enhance the penetration of ALA into HS. Additionally, ALA-ES was visualized in HS tissue for the first time by transmission electron microscopy (TEM). The irregular and collapsed ALA-ES suggest that they can squeeze through narrow spaces to the target area and release ALA into HS. Taking HSF as the target, the transcellular delivery of ALA-ES into HSF cells was investigated by intracellular protoporphyrin IX (PpIX) accumulation. The efficiency of PDT for HSF cells, including the formation of reactive oxygen species (ROS) and cell apoptosis, were also well investigated. Furthermore, the detailed changes of HSF were observed by TEM. The results strongly indicate that ALA-ES can facilitate ALA penetration into HSF cells, and can cause a higher level of cell apoptosis or necrosis than ALA-HA. ALA-ES with high EE is therefore a promising transdermal delivery system for topical ALA administration and has great potential in ALA-PDT of HS.

Recent Advances in Lipid-Based Vesicles and Particulate Carriers for Topical and Transdermal Application

In the recent decade, skin delivery (topical and transdermal) has gained an unprecedented popularity, especially due to increased incidences of chronic skin diseases, demand for targeted and patient compliant delivery, and interest in life cycle management strategies among pharmaceutical companies. Literature review of recent publications indicates that among various skin delivery systems, lipid-based delivery systems (vesicular carriers and lipid particulate systems) have been the most successful. Vesicular carriers consist of liposomes, ultradeformable liposomes, and ethosomes, while lipid particulate systems consist of lipospheres, solid lipid nanoparticles, and nanostructured lipid carriers. These systems can increase the skin drug transport by improving drug solubilization in the formulation, drug partitioning into the skin, and fluidizing skin lipids. Considering that lipid-based delivery systems are regarded as safe and efficient, they are proving to be an attractive delivery strategy for the pharmaceutical as well as cosmeceutical drug substances. However, development of these delivery systems requires comprehensive understanding of physicochemical characteristics of drug and delivery carriers, formulation and process variables, mechanism of skin delivery, recent technological advancements, specific limitations, and regulatory considerations. Therefore, this review article encompasses recent research advances addressing the aforementioned issues.

Sucrose esters improve the colloidal stability of nanoethosomal suspensions of (-)-epigallocatechin gallate for enhancing the effectiveness against UVB-induced skin damage

Nanoethosomal suspensions, composed of phospholipids, ethanol, and water, are novel lipid carriers. These suspensions have been reported to enhance the permeation of drugs into the skin as a result of the interdigitation effect of ethanol on the lipid bilayer of liposomes and by increasing the fluidity of lipids in the stratum corneum. The physical stability of the nanoethosomal suspension is still a critical research problem until now. This study investigated the commercial palm sucrose esters to improve the colloidal stability of nanoethosomal suspensions. The results indicated that palm sucrose esters (PSE) were effective for stabilizing nanoethosomal suspension of (-)-epigallocatechin gallate (EGCG) from green tea. A PSE concentration of 0.15% was optimal for a nanoethosomal suspension which gave mean diameter 75.5 ± 3.5 nm, zeta potential -30.8 ± 3.2 mV and polydispersity index 0.207 ± 0.017. Moreover, the effectiveness of stabilization was influenced by the degree of esterification of the sucrose esters: the sucrose polyesters could prolong the stability of nanoethosomes loaded with EGCG to a year, but the sucrose monoesters only provided less than 6 months of stabilization. EGCG nanoethosomal suspension stabilized by sucrose polyesters shows better inhibition effectiveness against UVB-induced skin damage than native EGCG. The nanoethosomal suspension has the potential for its utilization as skin care and other products. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 2416-2425, 2017.

(-)-Epigallocatechin gallate (EGCG)-nanoethosomes as a transdermal delivery system for docetaxel to treat implanted human melanoma cell tumors in mice

(-)-Epigallocatechin-3-O-gallate (EGCG), a versatile natural product in fresh tea leaves and green tea, has been investigated as a preventative treatment for cancers and cardiovascular disease. The objective of this study was to develop EGCG-nanoethosomes for transdermal delivery and to evaluate them for treating subcutaneously implanted human melanoma cell tumors. EGCG-nanoethosomes, composed of 0.2% EGCG, 2% soybean phosphatidylcholine, 30% ethanol, 1% Tween-80 and 0.1% sugar esters, were prepared and characterized using laser transmission electron microscopy. These nanoethosomes were smoother and more compact than basic-nanoethosomes with the same components except for EGCG. The effectiveness of transdermal delivery by EGCG-nanoethosomes was demonstrated in an in vitro permeability assay system using mouse skin. The inhibitory effect of docetaxel (DT) loaded in EGCG-nanoethosomes (DT-EGCG-nanoethosomes) was analyzed by monitoring growth of a subcutaneously implanted tumor from A-375 human melanoma cells in mice. Mice treated with DT-EGCG-nanoethosomes exhibited a significant therapeutic effect, with tumors shrinking, on average, by 31.5% of initial volumes after 14 d treatment. This indicated a potential for treating skin cancer. In a pharmacokinetic study, transdermal delivery by DT-EGCG-nanoethosomes enabled sufficient DT exposure to the tumor. Together, these findings indicated that EGCG-nanoethosomes have great potential as drug carriers for transdermal delivery.

Ethosomal nanocarriers: the impact of constituents and formulation techniques on ethosomal properties, in vivo studies, and clinical trials

Ethosomal systems are novel lipid vesicular carriers containing a relatively high percentage of ethanol. These nanocarriers are especially designed for the efficient delivery of therapeutic agents with different physicochemical properties into deep skin layers and across the skin. Ethosomes have undergone extensive research since they were invented in 1996; new compounds were added to their initial formula, which led to the production of new types of ethosomal systems. Different preparation techniques are used in the preparation of these novel carriers. For ease of application and stability, ethosomal dispersions are incorporated into gels, patches, and creams. Highly diverse in vivo models are used to evaluate their efficacy in dermal/transdermal delivery, in addition to clinical trials. This article provides a detailed review of the ethosomal systems and categorizes them on the basis of their constituents to classical ethosomes, binary ethosomes, and transethosomes. The differences among these systems are discussed from several perspectives, including the formulation, size, ζ-potential (zeta potential), entrapment efficiency, skin-permeation properties, and stability. This paper gives a detailed review on the effects of ethosomal system constituents, preparation methods, and their significant roles in determining the final properties of these nanocarriers. Furthermore, the novel pharmaceutical dosage forms of ethosomal gels, patches, and creams are highlighted. The article also provides detailed information regarding the in vivo studies and clinical trials conducted for the evaluation of these vesicular systems.

Compound antimalarial ethosomal cataplasm: preparation, evaluation, and mechanism of penetration enhancement

Malaria is still a serious public health problem in some parts of the world. The problems of recurrence and drug resistance are increasingly more serious. Thus, it is necessary to develop a novel antimalarial agent. The objectives of this study were to construct a novel compound antimalarial transdermal nanosystem–ethosomal cataplasm, to investigate its characteristics and efficiency, and to systematically explore the penetration-enhancing mechanisms of ethosomal cataplasm. Artesunate-loaded ethosomes and febrifugine-loaded ethosomes were prepared, and their characteristics were evaluated. Drug-loaded ethosomes were incorporated in the matrix of cataplasm to form the compound antimalarial ethosomal cataplasm. With the help of ethosomal technology, the accumulated permeation quantity of artesunate significantly increased at 8 hours after administration, which was 1.57 times as much as that of conventional cataplasm. Soon after administration, the ethosomal cataplasm could make a large quantity of antimalarial drug quickly penetrate through skin, then the remaining drug in the ethosomal cataplasm could be steadily released. These characteristics of ethosomal cataplasm are favorable for antimalarial drugs to kill Plasmodium spp. quickly and prevent the resurgence of Plasmodium spp. As expected, the ethosomal cataplasm showed good antimalarial efficiency in this experiment. The negative conversion rates were 100% and the recurrence rates were 0% at all dosages. The mechanism of penetration enhancement of the ethosomal cataplasm was systematically explored using an optics microscope, polarization microscope, and transmission electron microscopy. The microstructure, ultrastructure, and birefringent structure in skin were observed. Data obtained in this study showed that the application of ethosomal technology to antimalarial cataplasm could improve the transdermal delivery of drug, enhance the efficacy, and facilitate practical application in clinic.

How perifosine affects liposome-encapsulated drug delivery across a cell barrier

BACKGROUND

The development of efficient drug delivery systems to transport therapeutics across barrier-forming cells remains a challenge. Recently it was shown that liposomes containing perifosine, a synthetic analog of lysophosphatidylcholine, efficiently deliver liposome encapsulated content across barrier-forming cells.

METHODS

To elucidate the mechanism of the delivery, fluorescent and spin labeled analog of perifosine were synthesized and their transport from liposomes to the barrier-forming MDKC cells was measured.

RESULTS & CONCLUSION

Perifosine analogs are rapidly transported from liposomes into cell membranes. The total amount of perifosine accumulated in plasma membranes seems to be the most important factor in efficient transepithelial transport of liposome-encapsulated substances. Lysolipid-containing liposomal formulations seem to be promising candidates as drug delivery systems in general.

Formulation and evaluation of cholesterol-rich nanoemulsion (LDE) for drug delivery potential of cholesteryl-maleoyl-5-fluorouracil

It has been reported that cholesterol-rich nanoemulsions (LDE) can bind to low density lipoprotein (LDL) receptors which can concentrate anticancer drugs in the tissues via LDL receptor overexpression and reduced the adverse effects of the treatment. Therefore, in this study, LDE nanoemulsions of cholesteryl-maleoyl-5-fluorouracil (5-FU conjugate) were developed and evaluated in vitro. LDE nanoemulsions were prepared by high-energy emulsification technique. Developed formulations were characterized in terms of droplet size, polydispersity index, zeta potential, viscosity and refractive index. Optimized formulation (L5) was also evaluated for surface morphology using transmission electron microscopy (TEM). Developed formulations were subjected to in vitro drug release studies through dialysis membrane. The droplet size (50 nm), polydispersity index (0.109) and viscosity (32.16 cp) were found to be lowest for optimized formulation L5. The results of zeta potential indicated the stable formation of developed LDE nanoemulsions. TEM images of optimized formulation indicated non-spherical shape of droplets. About 97% of conjugate was found to be released from L5 after 24 h of study. Overall, these results indicated that developed LDE nanoemulsions could be successfully used for oral delivery of 5-FU conjugate.

Enhanced in vivo delivery of 5-fluorouracil by ethosomal gels in rabbit ear hypertrophic scar model

Applying Ethosomal Gels (EGs) in transdermal drug delivery systems has evoked considerable interest because of their good water-solubility and biocompatibility. However, there has not been an explicit description of applying EGs as a vehicle for hypertrophic scars treatment. Here, a novel transdermal EGs loaded with 5-fluorouracil (5-FU EGs) was successfully prepared and characterized. The stability assay in vitro revealed that 5-FU EGs stored for a period of 30 days at 4 ± 1 °C had a better size stability than that at 25 ± 1 °C. Furthermore, using confocal laser scanning microscopy, EGs labeled with Rhodamine 6 G penetrated into the deep dermis of the hypertrophic scar within 24 h in the rabbit ear hypertrophic model suggested that the EGs were an optional delivery carrier through scar tissues. In addition, the value of the Scar Elevation Index (SEI) of 5-FU EGs group in the rabbit ear scar model was lower than that of 5-FU Phosphate Buffered Saline gel and Control groups. To conclude, these results suggest that EGs delivery system loaded 5-fluorouracil is a perfect candidate drug for hypertrophic scars therapy in future.

Evaluation of skin viability effect on ethosome and liposome-mediated psoralen delivery via cell uptake

This study investigated the effect of skin viability on its permeability to psoralen delivered by ethosomes, as compared with liposomes. With decreasing skin viability, the amount of liposome-delivered psoralen that penetrated through the skin increased, whereas skin deposition of psoralen from both ethosomes and liposomes reduced. Psoralen delivery to human-immortalized epidermal cells was more effective using liposomes, whereas delivery to human embryonic skin fibroblast cells was more effective when ethosomes were used. These findings agreed with those of in vivo studies showing that skin psoralen deposition from ethosomes and liposomes first increased and then plateaued overtime, which may indicate gradual saturation of intracellular drug delivery. It also suggested that the reduced deposition of ethosome- or liposome-delivered psoralen in skin with reduced viability may relate to reduced cellular uptake. This work indicated that the effects of skin viability should be taken into account when evaluating nanocarrier-mediated drug skin permeation.

Challenges associated with Penetration of Nanoparticles across Cell and Tissue Barriers: A Review of Current Status and Future Prospects

Nanoparticles (NPs) have emerged as an effective modality for the treatment of various diseases including cancer, cardiovascular and inflammatory diseases. Various forms of NPs including liposomes, polymer particles, micelles, dendrimers, quantum dots, gold NPs and carbon nanotubes have been synthesized and tested for therapeutic applications. One of the greatest challenges that limit the success of NPs is their ability to reach the therapeutic site at necessary doses while minimizing accumulation at undesired sites. The biodistribution of NPs is determined by body's biological barriers that manifest in several distinct ways. For intravascular delivery of NPs, the barrier manifests in the form of: (i) immune clearance in the liver and spleen, (ii) permeation across the endothelium into target tissues, (iii) penetration through the tissue interstitium, (iv) endocytosis in target cells, (v) diffusion through cytoplasm and (vi) eventually entry into the nucleus, if required. Certain applications of NPs also rely on delivery through alternate routes including skin and mucosal membranes of the nose, lungs, intestine and vagina. In these cases, the diffusive resistance of these tissues poses a significant barrier to delivery. This review focuses on the current understanding of penetration of NPs through biological barriers. Emphasis is placed on transport barriers and not immunological barriers. The review also discusses design strategies for overcoming the barrier properties.

Development of an efficient transdermal drug delivery system with TAT-conjugated cationic polymeric lipid vesicles

Conventional liposomes (CLs) have been used as a transdermal drug delivery system for enhancing the delivery of hydrophilic drugs into/through the skin. However, their applications have been constrained by their limited penetration ability and poor stability. In this article, a new kind of transactivating transcriptional activator peptide (TAT)-conjugated polymeric lipid vesicles (TPLVs) formed from amphiphilic lysine-linoleic acid modified dextran (LLD) and cholesterol (Chol) has been prepared successfully. The newly developed TPLVs had a bilayer structure similar to CLs. The TPLVs also have smaller particle size, narrower distribution, higher positive charge and much better stability than the CLs; they remained stable in aqueous solutions for up to 60 days without aggregation. The in vitro and in vivo skin permeation studies revealed that TPLVs delivered a higher amount of drug through the skin than CLs, indicating enhanced drug transdermal activities. The synergetic effects of abovementioned features and the cell-penetrating peptide TAT might have contributed to the improved skin penetration ability of the TPLVs. Similar to CLs, TPLVs began to show limited cytotoxicity against human umbilical vein endothelial cells at a concentration of 200 μg mL^-1. The in vitro release profiles showed that the TPLVs achieved a sustained release of lidocaine. These results suggest that the TPLVs may be utilized as an efficient carrier to replace CLs for transdermal drug delivery.

Chemoprevention of skin cancer using low HLB surfactant nanoemulsion of 5-fluorouracil: a preliminary study

Oral delivery of 5-fluorouracil (5-FU) is difficult due to its serious adverse effects and extremely low bioavailability. Therefore, the aim of present investigation was to develop and evaluate low HLB surfactant nanoemulsion of 5-FU for topical chemoprevention of skin cancer. Low HLB surfactant nanoemulsions were prepared by oil phase titration method. Thermodynamically stable nanoemulsions were characterized in terms of droplet size distribution, zeta potential, viscosity and refractive index. Selected formulations and control were subjected to in vitro skin permeation studies through rat skin using Franz diffusion cells. Optimized formulation F9 was subjected to stability and in vitro cytotoxic studies on melanoma cell lines. Enhancement ratio was found to be 22.33 in formulation F9 compared with control and other formulations. The values of steady state flux and permeability coefficient for formulation F9 were found to be 206.40 ± 14.56 µg cm(-2) h(-1) and 2.064 × 10(-2) ± 0.050 × 10(-2 )cm h(-1), respectively. Optimized formulation F9 was found to be physical stable. In vitro cytotoxicity studies on SK-MEL-5 cancer cells indicated that 5-FU in optimized nanoemulsion is much more efficacious than free 5-FU. From these results, it can be concluded that the developed nanoemulsion might be a promising vehicle for chemoprevention of skin cancer.

Highly deformable and highly fluid vesicles as potential drug delivery systems: theoretical and practical considerations

Vesicles that are specifically designed to overcome the stratum corneum barrier in intact skin provide an efficient transdermal (systemic or local) drug delivery system. They can be classified into two main groups according to the mechanisms underlying their skin interaction. The first group comprises those possessing highly deformable bilayers, achieved by incorporating edge activators to the bilayers or by mixing with certain hydrophilic solutes. The vesicles of this group act as drug carriers that penetrate across hydrophilic pathways of the intact skin. The second group comprises those possessing highly fluid bilayers, owing to the presence of permeation enhancers. The vesicles of this group can act as carriers of drugs that permeate the skin after the barrier of the stratum corneum is altered because of synergistic action with the permeation enhancers contained in the vesicle structure. We have included a detailed overview of the different mechanisms of skin interaction and discussed the most promising preclinical applications of the last five years of Transfersomes® (IDEA AG, Munich, Germany), ethosomes, and invasomes as carriers of antitumoral and anti-inflammatory drugs applied by the topical route.