Dual-labeled visual tracer system for topical drug delivery by nanoparticle-triggered P-glycoprotein silencing

Using nanoparticle-based drug delivery systems as enhancers is a robust strategy for transdermal delivery; however, the mechanisms by which these systems promote transdermal penetration are still unclear. Here, we fabricated a dual-labeled nano drug delivery system that allows discrete visualization of both the drug and the nanoparticle carrier. To comprehensively examine its potential mechanism, we investigated its effects on human epidermal keratinocyte HaCaT cells, including changes in cell membrane potential, intracellular Ca²⁺ concentration, and Ca²⁺-ATPase activity. P-glycoprotein (P-gp) expression in nanoparticle-treated human dermal microvascular endothelial cells was detected by western blotting and immunofluorescence. Furthermore, the transdermal absorption and biodistribution of the dual-labeled nanoparticles were deeply investigated by skin permeability study in vitro and in vivo using fluorescence microscopy and in vivo imaging, respectively. In addition to reducing membrane potential, increasing the intracellular Ca²⁺ concentration, and decreasing Ca²⁺-ATPase activity, our results indicate that the dual-labeled nanoparticles can downregulate P-gp to promote transdermal absorption. Fluorescence and in vivo imaging visually demonstrated that the nanoparticle delivery system penetrated into the dermis through the stratum corneum. All these results indicate that this dual-labeled nano delivery system provides a new method for future in-depth visual explorations of transdermal drug delivery mechanisms.     

Design of meloxicam and lornoxicam transdermal patches: Preparation, physical characterization, ex vivo and in vivo studies

Transdermal patches of meloxicam (MX) and lornoxicam (LX) were aimed to be prepared in order to overcome their side effects by oral application. The strategy was formulation of optimized films to prepare transdermal patches by determination of physical properties and investigation of drug-excipient compatibility. As the next step, in vitro drug release, assesment of anti-inflammatory effect on Wistar Albino rats, ex vivo skin penetration and investigation of factors on drug release from transdermal patches were studied. Hydroxypropyl methylcellulose (HPMC) was concluded to be suitable polymer for formulation of MX and LX transdermal films indicating pharmaceutical quality required. MX and LX transdermal patches gave satisfactory results regarding to the edema inhibition in the assessment of anti-inflammatory effect. MX was found out to be more effective compared to LX on relieving of edema and swelling. These results were supported by data obtained from ex vivo penetration experiments of drug through rat skin. Indicative parameters like log P, molecular weight and solubility constraint on penetration rate of drugs also indicated good skin penetration. Transdermal patches of MX and LX can be suggested to be used especially for the immediate treatment of inflammated area since it displays anti-inflammatory effect, soon.     

Nano-formulations for transdermal drug delivery: A review

The different applications of nano-formulations (vesicles or nanoparticles and nanoemulsions) have been widely studied. Here, the classification, characteristics, transdermal mechanism, and application of the most popular nano-formulations in transdermal drug delivery system are reviewed.     

Penetration Process of a Hydrated Deep Eutectic Solvent Through the Stratum Corneum and its Application as a Protein Penetration Enhancer

The penetration mechanism of choline chloride-glycerol deep eutectic solvent (DES) through the stratum corneum (SC) as a potential solvent for a novel enhancer of protein penetration into the skin was investigated in a wide and small angle X-ray diffraction study. We found that DES penetrated through intercellular lipids but not the corneocytes. DES seemed to extract a portion of lipids of the short lamellae in the SC. Hydrated DES with a DES to water weight ratio of 9 to 1 (9DES-1H₂O) showed the strongest interaction with the lipids in the SC compared with water, DES, and hydrated DESs with another weight ratio of DES to water (DES : water=8 : 2). In a skin penetration test with a fluorescently labelled lysozyme, 9DES-1H₂O increased the amount of penetration through the SC by two-fold compared with HEPES buffer.     

External control of drug release and penetration. VI. Enhancing effect of ultrasound on the transdermal absorption of indomethacin from an ointment in rats.

The effect of an ultrasound (1 MHz) on transdermal absorption of indomethacin from an ointment was studied in rats. Ultrasound energy was supplied for between 5 and 20 min at a range of intensities (0.25, 0.5, 0.75, and 1 W cm-2), energy levels commonly used for therapeutic purposes. For evaluating skin penetration of indomethacin, the change of plasma concentration was measured. The pronounced effect of ultrasound on the transdermal absorption of indomethacin was observed at all ultrasound energy levels studied. The intensity and the time of application were found to play an important role in the transdermal phonophoretic delivery system of indomethacin; 0.75 W cm-2 appeared to be the most effective intensity in improving the transdermal absorption of indomethacin, while the 10 min ultrasound treatment was the most effective. Although the highest penetration was observed at an intensity of 0.75 W cm-2, 0.5 W cm-2 was preferred because intensities of less than 0.5 W cm-2 of ultrasound for 10 min did not result in any significant skin temperature rise nor did it have any destructive effect on rat skin. Progressively more skin damage was noted as the intensity and the time of application of ultrasound increased. When used at a proper intensity and time of application, ultrasound appears to be a safe technique for enhancing the passage of various drug molecules through human skin.     

Improved Dermal and Transdermal Delivery of Curcumin with SmartFilms and Nanocrystals

Poor aqueous solubility of active compounds is a major issue in today’s drug delivery. In this study the smartFilm-technology was exploited to improve the dermal penetration efficacy of a poorly soluble active compound (curcumin). Results were compared to the dermal penetration efficacy of curcumin from curcumin bulk suspensions and nanocrystals, respectively. The smartFilms enabled an effective dermal and transdermal penetration of curcumin, whereas curcumin bulk- and nanosuspensions were less efficient when the curcumin content was similar to the curcumin content in the smartFilms. Interestingly, it was found that increasing numbers of curcumin particles within the suspensions increased the passive dermal penetration of curcumin. The effect is caused by an aqueous meniscus that is created between particle and skin if the dispersion medium evaporates. The connecting liquid meniscus causes a local swelling of the stratum corneum and maintains a high local concentration gradient between drug particles and skin. Thus, leading to a high local passive dermal penetration of curcumin. The findings suggest a new dermal penetration mechanism for active compounds from nano-particulate drug delivery systems, which can be the base for the development of topical drug products with improved penetration efficacy in the future.     

Pharmacokinetics of aconitine in rat skin after oral and transdermal gel administrations

The purpose of this study was to evaluate percutaneous penetration and arrhythmogenic effects of aconitine after transdermal administration, compared with the oral route. Skin penetration of aconitine was tested by a microdialysis technique in rats and in vivo recovery was determined by retrodialysis. After oral and transdermal administration of aconitine, dialysate was sampled at 20 min intervals until the end of the experiment for the determination of concentration of aconitine in skin. Blood samples were collected and analyzed using a validated HPLC‐MS/MS method. In addition, we concurrently recorded the electrocardiogram (ECG). The in vivo recovery of aconitine in the skin was calculated to be 39.59%. The C_max values for aconitine absorbed into the skin after oral and transdermal administration were 1.51 ± 0.53 and 2723.8 ± 848.8 ng/mL, respectively, and within the plasma, 215.86 ± 79.29 and 20.92 ± 3.15 ng/mL. The C_max value for the plasma concentration of aconitine after oral administration was approximately 10 times higher than with the transdermal route. For oral administration, the ECG revealed various types of arrhythmias at a period of T_max, which is normal in transdermal gel administration. These results indicate that transdermal aconitine gel is a safe formulation that can deliver the drug in sufficient amounts and safe concentrations to produce therapeutic action in rats. Copyright © 2011 John Wiley & Sons, Ltd.     

氮酮对鼠角质层角蛋白作用的光谱证据

应用13CNMR和ATR-FTIR为测试手段,探讨角蛋白的分子运动自由度与堆积结构,以及氮酮对鼠角质层角蛋白的作用.经氮酮处理后,角蛋白主侧链碳的自旋晶格弛豫时间t1从7.9,8.2和2.1s分别减小到5.4,3.6和1.6s,表明氮酮作用加快了角蛋白所有碳的运动,获得了氮酮对鼠角质层角蛋白作用的确凿证据.同时,ATR-FTIR结果显示,经氮酮处理后,角蛋白的酰胺吸收峰带的峰位从1544.7cm^-1向低波数位移到1541.4cm^-1.结果表明氮酮可使部分角蛋白从α-螺旋型结构向β-折叠型结构和无规则卷曲型结构转变,导致角蛋白的堆积结构疏松,增大了角蛋白碳运动的自由度     

Enhanced transdermal delivery of zidovudine in rats and human skin

Zidovudine (azidothymidine, AZT), a potent antiviral agent acting on acquired immunodeficiency syndrome virus, was examined with regard to permeation through rat and human skin. A steady state plasma concentration of AZT after transdermal application in rats estimated from both pharmacokinetics data after i.v. administration and penetration rate through excised rat skin from 10% oleic acid (OA) aqueous solution shows penetration about 85 times higher compared to that from 10% OA would be needed for therapeutic efficacy. A mixed-solvent system consisted of 5% Sefsol-318 (S-318), 10% OA, 10% N-methyl-2-pyrrolidone (MP), 20% propylene glycol (PG) and water showed promising characteristics as a vehicle in terms of permeability of AZT through excised rat skin. The maximum flux of 0.41 mumol/cm2/h was observed in excised human skin after application of a gel formulation including S-318, OA, MP and PG. The result suggests a possible use of the gel formulation to gain an effective plasma concentration in humans.     

Enhancing effect of pyrrolidone derivatives on transdermal penetration of phenolsulfonphthalein and indomethacin from aqueous vehicle

We investigated the enhancing effect of three alkyl-2-pyrrolidones on transdermal penetration of phenolsulfonphthalein (phenol red) and indomethacin from an aqueous vehicle by using an in vitro technique with excised rat skin. The enhancers included 1-methyl- (I), 1-hexyl- (II) and 1-lauryl-2-pyrrolidone (III). These derivatives effectively enhanced the penetration and skin accumulation of phenol red and indomethacin. Lipophilic enhancers such as II and III showed particularly high enhancing effects. The penetration profiles of phenol red and indomethacin showed a lag phase followed by a linear increase. Compounds II and III showed long lag times. The enhancer penetration was also determined. Compounds I and II showed a slight penetration. Compound III showed little penetration but high skin accumulation.     

A Novel Methacryloyl Chitosan Hydrogel Microneedles Patch with Sustainable Drug Release Property for Effective Treatment of Psoriasis

Psoriasis is a chronic and recurrent skin disease that often requires long-term treatment, and topical transdermal drug delivery can reduce systemic side effects. However, it is still a challenge in efficient transdermal drug delivery for psoriasis treatment due to low penetration efficiency of most drugs and the abnormal skin conditions of psoriasis patients. Here, a safe and effective methacryloyl chitosan hydrogel microneedles (CSMA hMNs) patch is developed and served as a sustained drug release platform for the treatment of psoriasis. By systematically optimizing the CSMA preparation, CSMA hMNs with excellent morphological characteristics and strong mechanical properties (0.7 N needle⁻¹) are prepared with a concentration of only 3% (w/v) CSMA. As a proof-of-concept, methotrexate (MTX) and nicotinamide (NIC) are loaded into CSMA hMNs patch, which can produce a sustained drug release of 80% within 24 h in vitro. In vivo experiments demonstrated that the CSMA hMNs patch can effectively inhibit the skin thickening and spleen enlargement of psoriatic mice and has a good biosafety profile at sufficient therapeutic doses. This study provides a new idea for the preparation of hMN systems using modified CS or other biocompatible materials and offers an effective therapeutic option for psoriasis treatment.     

Mangiferin and Hesperidin Transdermal Distribution and Permeability through the Skin from Solutions and Honeybush Extracts (Cyclopia sp.)—A Comparison Ex Vivo Study

Polyphenolic compounds—mangiferin and hesperidin—are, among others, the most important secondary metabolites of African shrub Cyclopia sp. (honeybush). The aim of this study was to compare the percutaneous absorption of mangiferin and hesperidin from solutions (water, ethanol 50%, (v/v)) and extracts obtained from green and fermented honeybush (water, ethanol 50%, (v/v)). Research was performed with the Bronaugh cells, on human dorsal skin. The mangiferin and hesperidin distributions in skin layers (stratum corneum, epidermis, and dermis) and in acceptor fluid (in every 2, 4, 6, and 24 h) were evaluated by HPLC–Photodiode Array Coulometric and Coulometric Electrochemical Array Detection. The transdermal distribution of hesperidin was also demonstrated by fluorescence microscopy. Results indicated that mangiferin and hesperidin were able to cross the stratum corneum and penetrate into the epidermis and dermis. An advantage of hesperidin penetration into the skin from the water over ethanol solution was observed (451.02 ± 14.50 vs. 357.39 ± 4.51 ng/cm²), as well as in the mangiferin study (127.56 ± 9.49 vs. 97.23 ± 2.92 ng/cm²). Furthermore, mangiferin penetration was more evident from nonfermented honeybush ethanol extract (189.85 ± 4.11 ng/cm²) than from solutions. The permeation of mangiferin and hesperidin through the skin to the acceptor fluid was observed regardless of whether the solution or the honeybush extract was applied. The highest ability to permeate the skin was demonstrated for the water solution of hesperidin (250.92 ± 16.01 ng/cm²), while the hesperidin occurring in the extracts permeated in a very low capacity. Mangiferin from nonfermented honeybush ethanol extract had the highest ability to permeate to the acceptor fluid within 24 h (152.36 ± 8.57 ng/cm²).     

Improvement in bioavailability of transdermally applied flurbiprofen using tulsi (Ocimum sanctum) and turpentine oil

Penetration enhancing potential of tulsi and turpentine oil on transdermal delivery of flurbiprofen, a potent non-steroidal anti-inflammatory agent, was investigated. The transdermal permeation rate of flurbiprofen across the rat abdominal skin from binary solvent mixture composition of propylene glycol (PG):isopropyl alcohol (IPA) (30:70%, v/v) was 98.88 microg/cm(2)/h, significantly higher than other binary solvent mixtures. The corresponding steady state plasma concentration, 0.71 microg/ml, was much lower than required steady state plasma concentration of 3-5 microg/ml. Hence influence of tulsi and turpentine oil in the optimized binary solvent mixture along with the increased drug load on the flurbiprofen permeation was evaluated. The magnitude of the flux enhancement factor with turpentine oil and tulsi oil was 2.4 and 2.0 respectively at 5% (v/v) concentration beyond which there was no significant increase in the flux. Addition of 2% (w/v) hydroxypropyl methylcellulose (HPMC), as a thickening agent, resulted in desired consistency for the fabrication of patch with insignificant effect on permeation rate of flurbiprofen. The reservoir type of transdermal patch formulation, fabricated by encapsulating the flurbiprofen reservoir solution within a shallow compartment moulded from polyester backing film and microporous ethyl vinyl acetate membrane, did not modulate the skin permeation of flurbiprofen through rat skin in case of turpentine formulations whereas flux of formulations with tulsi oil was significantly altered. The influence of penetration enhancer and solvents on the anatomical structure of the rat skin was studied. Enhancement properties exhibited by turpentine oil and tulsi oil in optimized binary solvent mixture were superior as compared to solvent treated and normal control groups with negligible skin irritation. The fabricated transdermal patches were found to be stable. The bioavailability of flurbiprofen with reference to orally administered flurbiprofen in albino rats was found to increase by 2.97, 3.80 and 5.56 times with transdermal patch formulation without enhancer, tulsi and turpentine oil formulations, respectively. The results were confirmed by pharmacodynamic studies in rat edema inflammation model.     

Recent Progress in Transdermal Nanocarriers and Their Surface Modifications

Transdermal drug delivery system (TDDS) is an attractive method for drug delivery with convenient application, less first-pass effect, and fewer systemic side effects. Among all generations of TDDS, transdermal nanocarriers show the greatest clinical potential because of their non-invasive properties and high drug delivery efficiency. However, it is still difficult to design optimal transdermal nanocarriers to overcome the skin barrier, control drug release, and achieve targeting. Hence, surface modification becomes a promising strategy to optimize and functionalize the transdermal nanocarriers with enhanced penetration efficiency, controlled drug release profile, and targeting drug delivery. Therefore, this review summarizes the developed transdermal nanocarriers with their transdermal mechanism, and focuses on the surface modification strategies via their different functions.     

In Vitro Human Skin Penetration,Antioxidant and Antimicrobial Activity of Ethanol-Water Extract of Fireweed (Epilobium angustifolium L.)

Epilobium angustifolium L. is applied as an antiseptic agent in the treatment of skin diseases. However, there is a lack of information on human skin penetration of active ingredients with antioxidative potential. It seems crucial because bacterial infections of skin and subcutaneous tissue are common and partly depend on oxidative stress. Therefore, we evaluated in vitro human skin penetration of fireweed ethanol-water extracts (FEEs) by determining antioxidant activity of these extracts before and after penetration study using 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), and Folin–Ciocalteu methods. Microbiological tests of extracts were done. The qualitative and quantitative evaluation was performed using gas chromatography-mass spectrometry (GC-MS) and high-performance liquid chromatography (HPLC-UV) methods. The in vitro human skin penetration using the Franz diffusion chamber was assessed. The high antioxidant activity of FEEs was found. Gallic acid (GA), chlorogenic acid (ChA), 3,4-dihydroxybenzoic acid (3,4-DHB), 4-hydroxybenzoic acid (4-HB), and caffeic acid (CA) were identified in the extracts. The antibacterial activities were found against Serratia lutea, S. marcescens, Bacillus subtilis, B. pseudomycoides, and B. thuringiensis and next Enterococcus faecalis, E. faecium, Streptococcus pneumoniae, Pseudomonas aeruginosa, and P. fluorescens strains. In vitro penetration studies showed the penetration of some phenolic acids and their accumulation in the skin. Our results confirm the importance of skin penetration studies to guarantee the efficacy of formulations containing E. angustifolium extracts.     

立体异构单萜醇油酸酯的制备及促透活性评价

本文以互为立体异构体的香叶醇(GER)、橙花醇(NER)为先导化合物,采用酰氯酯化法合成油酸香叶醇酯(GER-dC18)、油酸橙花醇酯(NER-dC18),并考察GER、NER、GER-dC18、NER-dC18作为促透剂对多奈哌齐(DNP)的促透活性差异.通过体外释放试验、红外光谱法和分子模拟技术初步探究其促透机制,...     

Label free non-invasive imaging of topically applied actives in reconstructed human epidermis by confocal Raman spectroscopy

Raman spectroscopy has become a versatile tool for the in vivo characterization of skin. Here we describe use of Raman spectroscopy for high resolution optical cross sectioning to resolve skin constituents and administered drugs at the cellular level. Percutaneous penetration is typically studied using permeation cells with biopsies of animals or human skin. Although this technique provides valuable clinical data, little insight is gained in the microstructure of drug penetration (intercellular or transcellular) or in the mode of action of applied vehicles or penetration enhancers. Therefore, a Raman microspectroscopic method was combined with a confocal scanning setup to image the microstructure of commercially available skin models (SkinEthic^®) and the spatial distribution of penetrated actives. The models’ microstructure was scanned without any special treatment or environment such as cutting, staining, freezing, or application of vacuum. The non-invasive Raman images reveal the layered structure of stratum corneum. This in particular for lipids while water tends to be more evenly distributed. When penetration of the hydrophilic active glycerol and the lipophilic octyl methoxycinnamate, OMC, was studied, a strong correlation between the local distribution of skin constituents and the hydrophilic/lipophilic character of the active was observed.     

Percutaneous absorption of 1,3-dinitroglycerin and a trial of pharmacokinetic analysis

In order to estimate the pharmaceutical usefulness of 1,3-glyceryl dinitrate (1,3-GDN), an active metabolite of nitroglycerin, a trial transdermal delivery system designed to sustain a suitable plasma concentration of 1,3-GDN was produced using a porous membrane (Hipore 2100 or 4500) and it was a gel base or ethylhexyl acrylate-based adhesive (adhesive) and it was applied to rats. Additionally, for practical use of the transdermal system, a simple pharmacokinetic model to describe plasma 1,3-GDN levels after percutaneous (p.c.) application is presented. As a result, the drug was penetrated through the rat skin in vitro at a zero-order rate, although the penetration rate from the gel base was significantly greater than that from the adhesive. In vivo, the drug was rapidly absorbed through the rat skin, with a peak plasma level of 581 +/- 151 and 265 +/- 62 ng/ml for the gel ointment and adhesive systems without a porous membrane, respectively. The plasma levels after application of the systems with a membrane were relatively constant for a long time, indicating that the membranes act as a controlled-release barrier. The bioavailability of 1,3-GDN after gel base systems with and without a membrane was relatively high. The model presented was successfully able to describe the time course of plasma 1,3-GDN concentrations following p.c. application of the systems.     

Drug permeation through skin from matrix-type drug delivery systems

Nitroglycerin permeation through hairless mouse skin from various matrix-type transdermal delivery systems has been explained fairly well on the basis of a two-layer skin model. The diffusivity and solubility of the drug in the stratum corneum and in the viable skin have been calculated. The diffusivity in the stratum corneum was found to be affected by the type of delivery system, while that in the viable skin was hardly influenced by the delivery system. The loading dose, diffusivity and solubility of the drug in the delivery system were found to be the important design parameters for skin-control transdermal drug delivery and, therefore, the transdermal delivery system has to be optimized by controlling these three parameters to achieve a maximum rate of skin permeation with minimum drug loading dose.     

Development and characterization of eucalyptol microemulsions for topic delivery of curcumin

Microemulsions have received great attention for applications in transdermal drug delivery. The use of curcumin for treating various skin diseases like scleroderma, psoriasis, and skin cancer was extensively reported. The solubility of curcumin in various oils, surfactants, and cosurfactants was studied herein in order to find the optimal components for a transdermal delivery vehicle. Microemulsion systems composed of eucalyptol, polysorbate 80, ethanol, and water were developed as transdermal delivery vehicles for curcumin. Effects of the microemulsion composition on transdermal curcumin delivery were studied using Franz diffusion cells. The transdermal curcumin flux, permeability coefficient, and enhancement ratio were analyzed to evaluate the effects of eucalyptol/water ratios in the microemulsions. Pseudo-ternary phase diagrams of the eucalyptol microemulsions with various surfactant/cosurfactant ratios (1:1-1:3) were constructed to investigate their phase behaviors. Conductivity, interfacial tension, size, and viscosity data of the microemulsions were used to characterize the physicochemical properties of transdermal vehicles. The influence of the microemulsions on skin histology and on the delivery route was analyzed using hematoxylin/eosin staining and confocal laser scanning microscopy. In conclusion, microemulsions were successfully developed for transdermal curcumin delivery after screening various components and adjusting the oil/water ratios. The curcumin permeation rate of the microemulsion developed was 15.7-fold higher than that of the control (eucalyptol only). These results indicate that an eucalyptol microemulsion system is a promising tool for the percutaneous delivery of curcumin.