Enhanced Skin Permeation Research Articles

Single versus mixed edge activators in caffeine-loaded transfersomes: physicochemical and cytotoxicity assessment

The performance of transfersomes as nanovesicular systems to enhance the skin permeation of bioactive compounds may be modulated according to their composition of edge activators (EAs). Vesicle size, deformability, and encapsulation efficiency can be altered when using nonionic surfactants as EAs with opposing hydrophilic-lipophilic balance (HLB). Thus, this work aimed to assess the impact on the physicochemical properties and the in vitro cytotoxicity profile of transfersomal formulations composed of single or mixed EAs, with opposing HLB values. Transfersomes made of single or mixed nonionic surfactants (Tween® 80 and/or Span® 80) were prepared in the presence and absence of caffeine, used as a model hydrophilic compound. Single or mixed EAs-containing transfersomes displayed promising physicochemical properties for cutaneous applications and were found to be stable for one month of refrigerated storage. Moreover, all transfersomal formulations were compatible with a keratinocyte cell line upon 24 h treatment. Altogether, these preliminary data suggest that the use of mixed nonionic surfactants as EAs may be further explored to modulate the performance of transfersomes as skin permeation enhancers. Keywords: Vesicular systems, nanotechnology, nonionic surfactants, caffeine

Fluconazole and Curcumin Loaded Nanoemulsion Against Multiple Drug Resistance Dermatophytes

Purpose: Topical nanoemulsion comprising of fluconazole and curcumin was developed to target multiple drug resistance dermatophytes infection and to facilitate cutaneous delivery of these poorly water soluble drugs. Methods: Almond oil, sesame oil and paraffin light were used to formulate nanoemulsions and screened for the stability. The solubility of fluconazole and curcumin in surfactants, co-surfactants and oils was screened to decide the various components of the nanoemulsion. The oil phase was light paraffin whereas tween 80 and span 80 were the surfactants and ethanol was used as a co-surfactant. To identify the area of nanoemulsion existence, a pseudoternary diagram was drawn and optimum systems were developed. Drug-loading efficiency was assessed and the developed nanoemulsions were characterized for globule size, stability, robustness to dilution and pH. The optimized nanoemulsion was further evaluated for drug content, viscosity, skin permeation study (ex vivo) and assay of antifungal activity. Results: The globule size was below 200 nm and uniform for the optimized nanoemulsion formulation. It showed enhanced skin permeation (ex vivo) and better antifungal efficacy as compared to the native form of fluconazole and curcumin suspensions. Antimicrobial assay confirmed the synergistic effect of fluconazole and curcumin combination against multiple drug resistance Trychophytum rubrum and Trichophyton metagrophytes as compared to the fluconazole alone. Conclusion: The results clearly indicate an optimized delivery of fluconazole and curcumin in a synergistic way from the nanoemulsion formulation. This resulted in better penetration of these poorly soluble molecules and overall enhanced antifungal activity as compared to these drugs as such against multiple drug resistance dermatophytes.

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.

Ion-Pair Compounds of Strychnine for Enhancing Skin Permeability: Influencing the Transdermal Processes In Vitro Based on Molecular Simulation.

This research aimed to explore how Strychnine (Str) ion-pair compounds affect the in vitro transdermal process. In order to prevent the influence of different functional groups on skin permeation, seven homologous fatty acids were selected to form ion-pair compounds with Str. The in vitro permeation fluxes of the Str ion-pair compounds were 2.2 to 8.4 times that of Str, and Str-C10 had the highest permeation fluxes of 42.79 ± 19.86 µg/cm2/h. The hydrogen bond of the Str ion-pair compounds was also confirmed by Fourier Transform Infrared (FTIR) Spectroscopy, Nuclear Magnetic Resonance (NMR) Spectroscopy and molecular simulation. In the process of molecular simulation, the intercellular lipid and the viable skin were represented by ceramide, cholesterol and free fatty acid of equal molar ratios and water, respectively. It was found by the binding energy curve that the Str ion-pair compounds had better compatibility with the intercellular lipid and water than Str, which indicated that the affinity of Str ion-pair compounds and skin was better than that of Str and skin. Therefore, it was concluded that Str ion-pair compounds can be distributed from the vehicle to the intercellular lipid and viable skin more easily than Str. These findings broadened our knowledge about how Str ion-pair compounds affect the transdermal process.

Enhancement of skin permeation of fluorescein isothiocyanate-dextran 4 kDa (FD4) and insulin by thermalporation

Thermalporation has gained attention as a physical means to enhance skin permeation by creating micropores in the primary skin barrier, stratum corneum, which allows much higher permeation of middle and high molecular weight biopharmaceuticals. In the present study, a PassPort® system (PS) was used as a thermalporation device, and the obtained change in permeation resistance of drugs was evaluated using a parallel skin permeation-resistance model. In addition, the blood concentration–time profile after topical application of insulin was also investigated with the PS treatment.Fluorescein isothiocyanate-dextran (FD-4) and insulin were used as model middle molecular weight drugs. Micropores created by the PS treatment were measured using an optical microscope. An in vitro skin permeation and an in vivo pharmacokinetics experiments were done with FD-4 and insulin, respectively. Barrier function recovery after the PS treatment was evaluated with changes in the electrical skin resistance.About 960-fold higher skin permeation of FD-4 was observed by PSs treatment (4 milliseconds (ms), 200 micropores/cm2). A gradually increased blood concentration of insulin was observed by the PSs treatment, and the relative bioavailability of insulin was 21.1% compared with subcutaneous injection. Skin resistance value was dramatically decreased immediately after the PS treatment, but its value was turned into the initial one by 12 h.The thermalporation is effective for improving skin permeation of FD-4 and transdermal absorption of insulin. These results suggested that the PS treatment may be utilized to increase the skin permeation of topically applied FD-4 and insulin.

A Review on SLN and NLC for Management of Fungal Infections

Fungal disease is an invasive, serious, and systemic topical infection that affects the mucous membranes, tissues, and skin of humans. Oral medicines, on the other hand, have significant side effects, making topical treatments a viable alternative. Many antifungal medications applied through the skin in various conventional forms (gels or creams) may cause skin redness, erythema, stinging, and burning sensations. A promising approach to overcome the limitation of conventional form is the use of Nanocarriers for the treatment of skin infections since it allows targeted drug delivery, enhanced skin permeability, and controlled release and hence offers a lower risk of side effects. During the last few decades, lipid nanoparticles (LNPs) such as solid lipid nanoparticles (SLNs) and nanostructured lipid carriers (NLCs) have gained a lot of attention. SLNs were designed to overcome the drawbacks of conventional colloidal carriers, such as emulsions, liposomes, and polymeric nanoparticles, by offering benefits such as a good release rate and drug targeting with high physical stability. NLCs are SLNs that have been modified (Second generation SLN) to improve stability and capacity loading. This review discusses the pathophysiology of the fungal diseases, the application of SLN and NLC, its method of preparation, Characterization, and an overview of clinical trials on SLN and NLC for the treatment of fungal infection.

Enhanced Skin Delivery of Therapeutic Peptides Using Spicule-Based Topical Delivery Systems.

This study reports two therapeutic peptides, insulin (INS, as a hydrophilic model peptide) and cyclosporine A (CysA, as a hydrophobic one), that can be administrated through a transdermal or dermal route by using spicule-based topical delivery systems in vitro and in vivo. We obtained a series of spicules with different shapes and sizes from five kinds of marine sponges and found a good correlation between the skin permeability enhancement induced by these spicules and their aspect ratio L/D. In the case of INS, Sponge Haliclona sp. spicules (SHS) dramatically increased the transdermal flux of INS (457.0 ± 32.3 ng/cm2/h) compared to its passive penetration (5.0 ± 2.2 ng/cm2/h) in vitro. Further, SHS treatment slowly and gradually reduced blood glucose to 13.1 ± 6.3% of the initial level in 8 h, while subcutaneous injection resulted in a rapid blood glucose reduction to 15.9 ± 1.4% of the initial level in 4 h, followed by a rise back to 75.1 ± 24.0% of the initial level in 8 h. In the case of CysA, SHS in combination with ethosomes (SpEt) significantly (p < 0.05) increased the accumulation of CysA in viable epidermis compared to other groups. Further, SpEt reduced the epidermis thickness by 41.5 ± 9.4% in 7 days, which was significantly more effective than all other groups. Spicule-based topical delivery systems offer promising strategies for delivering therapeutic peptides via a transdermal or dermal route.

Fabrication of Tizanidine Loaded Patches Using Flaxseed Oil and Coriander Oil as a Penetration Enhancer for Transdermal Delivery.

Transdermal drug delivery is important to maintain plasma drug concentrations for therapeutic efficacy. The current study reports the design, formulation, and evaluation of tizanidine transdermal patches formulated using chitosan and thiolated chitosan, ethyl cellulose (EC), polyvinylpyrrolidone (PVP), and Eudragit RL100 in different ratios. The tizanidine patches were formulated using flaxseed oil and coriander oil in the concentrations of 1% v/w, 2% v/w, 3% v/w, 4% v/w, 5% v/w, and 10% v/w. The patches were subjected to characterization of physicochemical property (thickness, weight uniformity, drug content, efficiency, percentage moisture uptake/loss), in vitro drug release and drug permeation, skin irritation, in vivo application, pharmacokinetics analysis, and stability studies. The results indicate that the interaction of thiolated chitosan with the negative charges of the skin opens the tight junctions of the skin, whereas flaxseed and coriander oils change the conformational domain of the skin. The novelty of this study is in the use of flaxseed and coriander oils as skin permeation enhancers for the formulation of tizanidine transdermal patches. The formulations follow non-Fickian drug release kinetics. The FTZNE23, FTZNE36 and FTZNE54, with 5% v/w flaxseed oil loaded formulations, exhibited higher flux through rabbit skin compared with FTZNE30, FTZNE35, FTZNE42, and FTZNE47, formulations loaded with 10% v/w coriander oil. The study concludes that flaxseed oil is a better choice for formulating tizanidine patches, offering optimal plasma concentration and therapeutic efficacy, and recommends the use of flaxseed and coriander oil based patches as a novel transdermal delivery system for tizanidine and related classes of drugs.

A Rapid Method for the determination of Dehydrated alcohol (Ethanol) content in Clobetasol propionate foam by Non-polar Capillary Gas chromatography

Clobeatsol propionate foam is a topical class 1 corticosteroid used to treat itching and inflammatory arthritis on the skin occurred by allergic reactions, psoriasis and eczema. In the pharmaceutical aerosol products, Dehydrated alcohol (Ethanol) is the primary ingredient and its concentration level in the formulation composition plays a significant role in the regulation of aerosol rate, droplet shape and particle size. It can also act as solubilizer for active pharmaceutical ingredient, topical disinfectant and skin permeation enhancer. Hence accurate assay of Ethanol is a crucial quality control component. A simple and rapid gas chromatography method was developed to quantify Ethanol content in Clobetasol propionate foam drug product using fused silica glass tube non-polar capillary column (HP-5, 30 m, 0.53 mm, 1.5 µm). Ethanol in the sample was diluted with methanol after adding suitable amount of internal standard, the isopropyl alcohol solution.The developed method is precise, linear and accurate in the range of 5 mg/mL to 15 mg/mL of nominal concentration of ethanol i.e. 10 mg/mL . The presented method has an advantage of a very quick gas chromatographic separation (less than 16 min) and therefore is highly suitable for in-process and stability analysis of Ethanol content in Clobetasol propionate foam drug product.

Lyotropic liquid crystal-based transcutaneous peptide delivery system: Evaluation of skin permeability and potential for transcutaneous vaccination

Transcutaneous drug delivery is a promising method in terms of drug repositioning and reformulation because of its non-invasive and easy-to-use features. To overcome the skin barrier, which is the biggest challenge in transcutaneous drug delivery, a number of techniques, such as microemulsion, solid-in-oil dispersions and liposomes, have been studied extensively. However, the low viscosity of these formulations limits drug retention on the skin and reduces patient acceptability. Although viscosity can be increased by adding a thickening reagent, such an addition often alters formulation nanostructures and drug solubility, and importantly, decreases skin permeability. In this study, a gel-like lyotropic liquid crystal (LLC) was used as a tool to enhance skin permeability. In particular, we prepared 1-monolinolein (ML)-based LLCs with different water contents. All LLCs significantly enhanced skin permeation of a peptide drug, an epitope peptide of melanoma, despite their high viscoelasticity. Fourier transform infra-red spectroscopic analysis of the skin surface treated with the LLCs revealed that the gyroid geometry more strongly interacted with the lamellar structure inside the stratum corneum (SC) than the diamond geometry. Finally, as the result of the in vivo tumor challenge experiment using B16F10 melanoma-bearing mice, the LLC with the gyroid geometry showed stronger vaccine effect against tumor than a subcutaneous injection. Collectively, ML-based LLCs, especially with the gyroid geometry, are a promising strategy to deliver biomacromolecules into skin. Statement of significanceTranscutaneous drug delivery is a promising method for drug repositioning and reformulation because of its non-invasive and easy-to-use features. To overcome the skin barrier, which is the biggest challenge in transcutaneous drug delivery, we used a gel-like lyotropic liquid crystal (LLC) as a novel tool to enhance skin permeability. In this paper, we demonstrated that an LLC with a specific liquid crystalline structure has the highest skin permeation enhancement effect for a peptide antigen as a model drug. Moreover, the peptide antigen-loaded LLC showed a vaccine effect that was comparable to a subcutaneous injection in vivo. This study provides a basis for designing a transcutaneous delivery system of peptide drugs with LLC.

The Emerging Role of Ionic Liquid-Based Approaches for Enhanced Skin Permeation of Bioactive Molecules: A Snapshot of the Past Couple of Years.

Topical and transdermal delivery systems are of undeniable significance and ubiquity in healthcare, to facilitate the delivery of active pharmaceutical ingredients, respectively, onto or across the skin to enter systemic circulation. From ancient ointments and potions to modern micro/nanotechnological devices, a variety of approaches has been explored over the ages to improve the skin permeation of diverse medicines and cosmetics. Amongst the latest investigational dermal permeation enhancers, ionic liquids have been gaining momentum, and recent years have been prolific in this regard. As such, this review offers an outline of current methods for enhancing percutaneous permeation, highlighting selected reports where ionic liquid-based approaches have been investigated for this purpose. Future perspectives on use of ionic liquids for topical delivery of bioactive peptides are also presented.

A Review on Film Forming Drug Delivery Systems

Conventional dosage forms for topical and transdermal drug delivery have several disadvantages related mainly to its poor skin permeation and patient compliance. Many approaches have been developed to improve these dosage forms. Film forming drug delivery systems represents a recent advancement in this field. It provides improved patient compliance with enhanced skin permeation of drugs. In its simplest form, these consist of a polymeric solution, usually in a supersaturated state, in a suitable solvent. A plasticizer is usually added to improve the flexibility and enhance the tensile strength to the film. It is also possible to control and sustain the drug release from the films by controlling the polymeric content, concentration of plasticizer, or formulation with other additives. In this review, we are summarizing the mechanism of formation of these films as well as its types and possible applications. The main ingredients, properties, and evaluation of the various film forming delivery systems are also discussed.

Influence of Stabilizer on the Development of Luteolin Nanosuspension for Cutaneous Delivery: An In Vitro and In Vivo Evaluation.

Luteolin is a natural drug used as an antioxidant and anti-inflammatory, but unfortunately, it possesses low water solubility, which hinders its delivery via the skin. The main objective of this study was to prepare a luteolin-loaded nanosuspension by the antisolvent precipitation/sonication technique and study the effects of four stabilizers (two nonionic stabilizers, Pluronic F127 and Tween 80, and two polymeric stabilizers, HPMC and alginate) on the physicochemical properties of the prepared formulations. The selected formulations were incorporated into a gel base to evaluate their skin permeability and anti-inflammatory efficacy. The particle size was in the nanosize range (in the range from 468.1 ± 18.6 nm to 1024.8 ± 15.9 nm), while the zeta potential was negative and in the range from −41.7 ± 6.3 mV to −15.3 ± 1.9 mV. In particular, alginate-stabilized nanosuspensions showed the smallest particle size, the highest zeta potential value, and excellent stability due to the dual stabilizing effects (electrostatic and steric effects). The DSC results revealed a less crystalline structure of luteolin in lyophilized NS2 and NS12. Formulations stabilized by 1% Pluronic (NS2) and 2% alginate (NS12) were incorporated into a carbopol 940 gel base and showed good organoleptic character (homogenous with no evidenced phase separation or grittiness). In vitro dissolution studies showed that NS12 enhanced luteolin release rates, indicating the effect of particle size on the drug release pattern. On the other hand, NS2 showed enhanced skin permeability and anti-inflammatory effect in a carrageenan-induced paw edema model, revealing the surface activity role of the stabilizers. In conclusion, while alginate increased the nanosuspension stability by means of dual stabilizing effects, Pluronic F127 improved the skin delivery and pharmacodynamic efficacy of luteolin.

Human Skin Permeation Enhancement Using PLGA Nanoparticles Is Mediated by Local pH Changes.

The steady improvement and optimization of transdermal permeation is a constant and challenging pharmaceutical task. In this study the influence of poly(lactide-co-glycolide) (PLGA) nanoparticles on the dermal permeation of the anti-inflammatory drug flufenamic acid (FFA) was investigated. For this aim, different vehicles under non-buffered and buffered conditions and different skin models (human heat separated epidermis and reconstructed human epidermis equivalents) were tested. Permeation experiments were performed using static Franz diffusion cells under infinite dosing conditions. Already the presence of drug-free nanoparticles increased drug permeation across the skin. Drug permeation was even enhanced when applying drug-loaded nanoparticles. In contrast, buffered vehicles with different pH values (pH 5.4–7.4) revealed the influence of the pH on the permeation of FFA. The change of the surrounding pH of the biodegradable nanoparticulate system was demonstrated and visualized using pH-sensitive fluorescent probes. While a potential contribution of hair follicles could be ruled out, our data suggest that the enhanced permeation of FFA through human skin in the presence of PLGA nanoparticles is mediated by a locally decreased pH during hydrolytic degradation of this polymer. This hypothesis is supported by the observation that skin permeation of the weak base caffeine was not affected.

Enhancement of Skin Delivery of Drugs Using Proposome Depends on Drug Lipophilicity.

The study aims to investigate the propylene glycol-based liposomes named ‘proposomes’ in enhancing skin permeation of drugs with different physicochemical properties. Ibuprofen, tofacitinib citrate, rhodamine B, and lidocaine were loaded into proposomes. These drug formulations were analyzed for particle size, zeta potential, polydispersity index, entrapment efficiency, and in vitro skin permeation. The confocal laser scanning microscopy was performed on skin treated with calcein and rhodamine B laden proposomes. The transdermal delivery relative to physicochemical properties of drugs such as logP, melting point, molecular weight, solubility, etc., were analyzed. We tested the safety of the proposomes using reconstructed human skin tissue equivalents, which were fabricated in-house. We also used human cadaver skin samples as a control. The proposomes had an average diameter of 128 to 148 nm. The drug’s entrapment efficiencies were in the range of 42.9–52.7%, translating into the significant enhancement of drug permeation through the skin. The enhancement ratio was 1.4 to 4.0, and linearly correlated to logP, molecular weight, and melting point. Confocal imaging also showed higher skin permeation of calcein and rhodamine B in proposome than in solution. The proposome was found safe for skin application. The enhancement of skin delivery of drugs through proposomes was dependent on the lipophilicity of the drug. The entrapment efficiency was positively correlated with logP of the drug, which led to high drug absorption.

Formulation, Optimization, and Ex-vivo Evaluation of Novel Lipid Carriers for Enhanced Transdermal Delivery of Hydroquinone

Background: HQ is used for hyper-pigmentation treatment using conventional creams and gels. These formulations show various disadvantages like poor skin permeation, allergic reactions, and repeated use and decreasing patient compliance. Objectives: The present work involved formulation, statistical optimization, and characterization of Nanostructured Lipid Carriers (NLCs) for efficient topical delivery of hydroquinone (HQ) for hyperpigmentation treatment. Methods: The NLCs were optimized exploring Box–Behnken Design (BBD) using three independent variables and two dependent variables. Formulation having the minimum size and maximum drug entrapment was considered as optimized formulation. The optimized formulation was evaluated for drug release followed by its freeze-drying. The freeze-dried formulation was subjected to Differential Scanning Calorimetry (DSC) analysis, X-Ray Diffraction (XRD) analysis, and Fourier Transform-Infrared spectroscopy (FT-IR) analysis. Furthermore, NLCs based gel was prepared by using Carbopol 934 as a gelling agent. NLCs based gel was evaluated for skin permeation, skin retention, and skin distribution (through confocal microscopic analysis) using pig ear skin. Results: Optimized NLCs showed smaller particle size [(271.9 ± 9) nm], high drug entrapment [(66.4 ± 1.2) %], tolerable polydispersity index (PDI) (0.221 ± 0.012), and zeta potential [(-25.9 ± 1.2) mV]. The FT-IR analysis revealed excellent compatibility between HQ and other excipients. The Carbopol 934 gel containing NLCs showed high transdermal flux [(163 ± 16.2) μg/cm2/h], permeability coefficient (0.0326 ± 0.0016), and skin permeation enhancement ratio (3.7 ± 0.4) compared to marketed cream of HQ. The results of confocal microscopic (CLSM) analysis revealed the accumulation of optimized NLCs in the lower epidermal layers of skin. Conclusion: NLCs based gel was considered effective in the topical delivery of HQ to treat hyperpigmentation due to high skin permeation, skin retention, and prolonged release of HQ.

Cholesterol and Phospholipid-free Multilamellar Niosomes Regulate Transdermal Permeation of a Hydrophobic Agent Potentially Administrated for Treating Diseases in Deep Hair Follicles

We designed cholesterol- and phospholipid-free multilamellar niosomes (MLNs) structured by glyceryl monooleate (GMO) and poloxamer 407 (F127), and evaluated their capacity for transdermal drug delivery. The optimized MLNs had a mean size of 97.88 ± 63.25 nm and an encapsulation efficiency of 82.68% ± 2.14%. The MLNs exhibited a remarkable sustained cargo release, and improved the permeation of the stratum corneum. Compared with the tincture, lower transdermal flux but higher skin deposition of aconitine in vitro were achieved in the MLN group (p < 0.05). Additionally, both water-soluble rhodamine B- and liposoluble coumarin 6-labeled MLNs were found to penetrate deeply into the skin through the hair follicles and could be internalized by fibroblasts Notably, the MLNs possessed greater wettability, and the study focused on delivery to deeper hair follicles and up to the outer hair sheath, which showed advantages for treating diseases of hair follicles, and was potentially superior to the hydrophobic PLGA nanoparticles (diameter: 637.87 ± 22.77 nm) which mainly accumulated in superficial hair follicles. Hair follicles were therefore demonstrated to be an important way to enhance skin permeability, and MLNs are a promising alternative for topical and transdermal drug delivery.

FORMULATION AND EVALUATION OF SIMVASTATIN LOADED MICROEMULSION BASED GEL: IN VITRO CHARACTERIZATION

The Simvastatin loaded microemulsion based gel was formulated and in-vitro evaluation was done for the treatment of diabetic wound healing. Simvastatin is BCS class II drug which promotes wound healing by increasing the production of vascular endothelial growth factor (VEGF). Microemulsions (MEs) are oil and water colloidal system stabilized by the mixture of surfactant and co-surfactant offering enhance skin permeability for both hydrophobic and hydrophilic drugs. At first, microemulsion (ME) was prepared by water titration method and the existence of ME region was determined using pseudo-ternary phase diagram. Formulations were prepared using oil (oleic acid), Tween 80 and PEG 400 as surfactant and co-surfactant. Optimization of formulation was done using 32 factorial designs. Carbopol 940 was used as gelling agent for preparing microemulsion gel. The formulations were evaluated for physical appearance globule size, polydispersity index, zeta potential, percent transmittance, thermodynamic stability, dilution test, drug content, and in vitro drug release. The optimized formulation of ME showed average globule size of 151 nm and the optimized ME gel had a homogeneous texture, showed good spreadability and in vitro drug release. The present study indicates the simvastatin loaded microemulsion gel could act as promising vehicle for topical drug delivery of drug for diabetic wound healing.

Development of a novel nanoemulgel formulation containing cumin essential oil as skin permeation enhancer

Essential oils have been proposed as promising non-toxic transdermal permeation enhancers. Their use is limited because of their low water solubility. The use of nanotechnology-based strategies is one of the ways to overcome this limitation. This study aimed to explore the transdermal permeation enhancing capability of cumin essential oil in nanoemulgel systems containing diclofenac sodium. Cumin essential oil nanoemulsion was produced by high-pressure homogenization technique. The formulation was optimized by changing HLB values in a range of 9.65–16.7 using different surfactant mixtures, namely, Tween 20, Tween 80, and Span 80. Preparations were characterized by polydispersity index, droplet size, and zeta potential. Nanoemulsion with concentrations of 2 and 4% essential oil was incorporated into 0.75% Carbopol gel matrix to make nanoemulgel formulation, and its permeation enhancing effect was performed through Franz diffusion cells. Antinociceptive activities of the formulations were measured in thermal (tail-flick) and chemical (formalin) models of nociception in mice. Characterization exhibited that at HLB value of 9.65, the smallest particle size (82.20 ± 5.82 nm) was formed. By increasing the essential oil percentage in the nanoemulgel from 1 to 2%, the permeation of diclofenac increased from 28.39 ± 1.23 to 34.75 ± 1.07 µg/cm2 at 24 h. The value of permeation from the simple gel (21.18 ± 2.51 µg/cm2) and the marketed product (22.97 ± 1.92 µg/cm2) was lower than the formulations containing essential oil. Nanoemulgel of diclofenac containing essential oil showed stronger antinociceptive effects in formalin and tail-flick tests than simple diclofenac gel and marketed formulation. In conclusion, the study proved that nanoemulgel formulation containing cumin essential oil could be considered as a promising skin enhancer to enhance the therapeutic effect of drugs.Graphical abstract

Lyotropic Liquid Crystal-Based Transcutaneous Peptide Delivery System: Evaluation of Skin Permeability and Potential for Transcutaneous Vaccination

Transcutaneous drug delivery is a promising method in terms of drug repositioning and reformulation because of its non-invasive and easy-to-use features. To overcome the skin barrier, which is the biggest challenge in transcutaneous drug delivery, a number of techniques, such as microemulsion, solid-in-oil dispersions and liposomes, have been studied extensively. However, the low viscosity of these formulations limits drug retention on the skin and reduces patient acceptability. Although viscosity can be increased by adding a thickening reagent, such an addition often alters formulation nanostructures and drug solubility, and importantly, decreases skin permeability. In this study, a gel-like lyotropic liquid crystal (LLC) was used as a tool to enhance skin permeability. In particular, we prepared 1-monolinolein-based LLCs with different water contents. All LLCs showed enhanced skin permeation of a peptide drug, despite their viscoelastic property. Fourier transform infra-red spectroscopic analysis of the skin surface treated with the LLCs revealed that the gyroid geometry more strongly interacted with the lamellar structure inside the stratum corneum (SC) than the diamond geometry. Collectively, our novel LLCs, especially with the gyroid geometry, are a promising strategy to deliver biomacromolecules into skin.