乙醇脂质体、二元醇脂质体及传递体对多奈哌齐经皮转运的对比性研究

目的:制备多奈哌齐乙醇脂质体、二元醇脂质体和传递体,并比较皮肤渗透性,从而进一步有效优化药物的经皮转运。方法:通过形态,粒径分布,Zeta电位值和包封率对多奈哌齐乙醇脂质体、二元醇脂质体及传递体进行了初步表征,运用Franz扩散池和共聚焦激光扫描电镜考察了3种囊泡的经皮转运情况。结果:当二元醇脂质体包封率最高(89.1±0.42)%时,乙醇-丙二醇=7∶3,且二元醇脂质体(乙醇-丙二醇为7∶3,W/W)在皮肤中24 h的累积渗透百分数分别是乙醇脂质体和传递体的3.9和5.4倍。结论:二元醇醇脂质体(乙醇-丙二醇为7∶3,W/W)时,有效地改善了药物在醇脂质体中的包封率,且显著增加的药物在皮肤中的累积量。     

Comparative study of liposomes,transfersomes and ethosomes as carriers for improving topical delivery of celecoxib

Topical administration of celecoxib proved to be an effective mean of preventing skin cancer development and improving anticancer drugs effectiveness in skin tumors treatment. The aim of this study was the development of an effective topical formulation of celecoxib, able to promote drug skin delivery, providing its in depth penetration through the skin layers. Three kinds of vesicular formulations have been investigated as drug carriers: liposomes containing a surfactant, or transfersomes and ethosomes, containing suitable edge activators. Firstly, the effect of membrane composition variations on the system performance has been evaluated for each vesicle type. Selected formulations were characterized for particle size, polydispersity index and encapsulation efficiency. The best formulations were subjected to ex vivo permeation studies through excised human skin. All vesicular formulations markedly (p < 0.001) improved the drug amount penetrated into the skin with respect to an aqueous suspension, from 2.0 to 6.5, up to 9.0 folds for liposomes, transfersomes and ethosomes, respectively. In particular, ethosomes containing Tween 20 as edge activator not only showed the best vesicle dimensions and homogeneity, and the highest encapsulation efficacy (54.4%), but also enabled the highest increase in drug penetration through the skin, probably due to the simultaneous presence in their composition of ethanol and Tween 20, both acting as permeation enhancers. Therefore, among the various vesicular formulations examined in the study, Tween 20-ethosomes can be considered the most promising one as carrier for topical celecoxib applications aimed to prevent skin cancer development and increase the anticancer drugs effectiveness against skin tumors.     

Nanocarriers to Enhance the Accumulation of Vitamin K1 into the Skin

Purpose

Vitamin K1 (VK1) is a molecule abundant in some species of leaf vegetables with beneficial effects in humans following administration on the skin. This work investigates the possibility to use formulations based on lipid vesicles, namely liposomes, transfersomes and ethosomes, suitable to be administered on the skin by nebulization and alternative to fat semisolid preparations present on the market.

Methods

Lipid vesicles encapsulating VK1 were prepared and characterized. Ex-vivo experiments on Franz cells were carried out to study the VK1 accumulation/permeation in/through the skin. Vesicles interaction with the skin was investigated by confocal laser scanning microscopy (CLSM) and attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy.

Results

All developed carriers were stable following long-term storage and were not altered following nebulization. In ex-vivo experiments, vesicles with the highest deformability index, namely transfersomes and ethosomes, led to an enhanced VK1 accumulation/permeation into/through the skin. Interestingly, the nebulization of the vesicles led to a further increase of VK1 accumulation into the skin.

Conclusions

In conclusion, to achieve a local effect of VK1 on the skin, the topical nebulization of VK1-containing transfersomes could offer a good compromise between a high VK1 penetration into the skin and a limited permeation through it.

     

布洛芬二元醇脂质体的制备与评价

目的:制备布洛芬二元醇脂质体并对其进行体外评价。方法:采用注入法制备布洛芬二元醇脂质体,以包封率为指标优化处方中乙醇与丙二醇比例;采用Franz扩散池进行离体皮肤渗透试验,测定布洛芬在接收液内的累积渗透量及皮内滞留量。结果:乙醇与丙二醇比例为7∶3时制得的布洛芬二元醇脂质体包封率最高(73.6±1.4)%,其透过皮肤进入接收液中的累积渗透量为乙醇脂质体的1.82倍。二元醇脂质体[乙醇-丙二醇(7∶3)]和乙醇脂质体24 h皮肤中药物滞留量分别为43.67±2.11和38.02±1.44。结论:二元醇脂质体可有效提高布洛芬的皮肤渗透量及皮内滞留量。     

Effect of Penetration Enhancers on the Transdermal Delivery of Bupranolol Through Rat Skin

Bupranolol (BPL) is a suitable drug candidate for transdermal drug delivery system development based on its favorable physicochemical and pharmacokinetic properties. The effect of different penetration enhancers on the permeation of BPL across rat skin was studied using side-by-side diffusion cells. 2-pyrrolidone (PY), 1-methyl-2-pyrrolidone (MPY), and propylene glycol (PG) at various concentrations were used as penetration enhancers along with 0.4% w/v aqueous suspension of BPL. Menthol at different concentrations in isopropanol-water (6:4) mixture also was used as an enhancer wherein BPL at 0.4% w/v was completely solubilized. Skin pretreatment studies were carried out with all the above enhancers to understand their role in the penetration enhancement effect. PY and MPY at 5% w/v concentrations increased the permeation of BPL by 3.8- and 2.4-fold, respectively, versus control (p < .01). PG at 10% and 30 w/v concentrations increased the flux of BPL by 2.5- and 5.0-fold, respectively, versus control (p < .001). Menthol at 2% w/v concentration increased the flux of BPL by 3.8-fold (p < .01) and further increase in menthol concentration significantly decreased the flux of BPL. Overall, pyrrolidones and menthol at low concentrations (5% w/v or less) and PG at 30% w/v concentration were effective as penetration enhancers for BPL.     

Comparative study of liposomes,transfersomes, ethosomes and cubosomes for transcutaneous immunisation: characterisation and in vitro skin penetration

Objectives Lipid colloidal vaccines, including liposomes, transfersomes, ethosomes and cubosomes, were formulated, characterised and investigated for their ability to enhance penetration of a peptide vaccine through stillborn piglet skin in vitro. Methods Liposomes and transfersomes were formulated using a film‐hydration method, ethosomes using a modified reverse phase method and cubosomes using a lipid precursor method. The size, zeta potential, peptide loading and interfacial behaviour of the formulations were characterised. Skin penetration studies were performed using Franz diffusion cells with piglet skin as the membrane. The localization of peptide in the skin was examined using confocal laser scanning microscopy. Key finding The various formulations contained negatively charged particles of similar size (range: 134–200 nm). Addition of the saponin adjuvant Quil A to the formulations destabilised the monolayers and reduced peptide loading. Cubosomes and ethosomes showed superior skin retention compared with the other systems. Confocal laser scanning microscopy showed greater peptide penetration and accumulation in the skin treated with cubosomes and ethosomes. With the other systems peptide was only located in the vicinity of the hair follicles and within the hair shaft. Conclusions We conclude from the in‐vitro studies that cubosomes and ethosomes are promising lipid carriers for transcutaneous immunisation.     

Nanotransfersomes of carvedilol for intranasal delivery: formulation,characterization and in vivo evaluation

Context: Development of carvedilol-loaded transfersomes for intranasal administration to overcome poor nasal permeability and hepatic first pass effect so as to enhance its bioavailability.

Objective: The purpose of this study was to develop carvedilol-loaded transfersomes containing different edge activators (EAs) then evaluating the in vivo behavior of the optimized formula in rabbits.

Methods: The vesicles were prepared by incorporating different EAs including Span 20, Span 60, Tween 20, Tween 80, and sodium deoxycholate (SDC) in the lipid bilayer and each EA was used in three different ratios with respect to phosphatidylcholine (PC) including 95:5%, 85:15%, and 75:25% w/w (PC:EA). Evaluation of transfersomes was carried out in terms of shape, size, entrapment efficiency (EE), in vitro release, ex vivo permeation, confocal laser scanning microscopy (CLSM), and stability studies. The pharmacokinetic study of the optimized formula was conducted in rabbits.

Results: The mean diameter of the vesicles was in the range of 295–443?nm. Transfersomes prepared with 95:5% (w/w) (PC:EA) ratio showed highest EE% where Span 60 gave the highest values. Whereas those prepared using 85:15% w/w ratio showed highest percentages of drug release where SDC was superior to other EAs. The developed transfersomes exhibited significantly higher amounts of carvedilol permeated through nasal mucosa. CLSM of formula T14 containing SDC with 85:15% (w/w) (PC:EA) ratio revealed high permeation across the nasal mucosa.

Conclusion: The nanotransfersomal vesicles were significantly more efficient in nasal delivery of carvedilol with absolute bioavailability of 63.4%.     

Microwave-aided skin drug penetration and retention of 5-fluorouracil-loaded ethosomes

ABSTRACT

Objectives: Skin drug retention is required in local treatment of skin cancer. This study investigated the interplay effects of ethosomes and microwave in transdermal drug delivery. Skin pre-treatment by microwave and applied with liquified medicine is deemed to ‘cement’ the skin thereby raising skin drug deposition.

Methods: 5-fluorouracil-loaded ethosomes were prepared and subjected to size, zeta potential, morphology, drug content, drug release and skin permeation tests. The molecular characteristics of untreated, microwave and/or ethosome-treated skins were examined by Fourier transform infrared and raman spectroscopy, thermal and electron microscopy techniques.

Results: The skin drug retention was promoted using larger ethosomes with negative zeta potentials that repelled anionic lipids of skin and hindered vesicle permeation into deep layers. These ethosomes had low ethanol content. They were less able to fluidize the lipid and defluidize the protein domains at epidermis to enlarge aqueous pores for drug permeation. Pre-treatment of skin by 2450 MHz microwave for 2.5 min further increased skin drug penetration and retention of low ethanol ethosomes and provided lower drug permeation than cases treated for 1.15 min and 5 min. A 2.5 min treatment might be accompanied by specific dermal protein fluidization via C=O moiety which translated to macromolecular swelling, narrowing of intercellular spaces at lower skin layers, increased drug retention and reduced drug permeation.

Conclusion: Ethosomes and microwave synergized to promote skin drug retention.     

Nanosized ethosomes-based hydrogel formulations of methoxsalen for enhanced topical delivery against vitiligo: formulation optimization,in vitro evaluation and preclinical assessment

The present investigation aimed for the development and characterization of ethosomes-based hydrogel formulations of methoxsalen for enhanced topical delivery and effective treatment against vitiligo. The ethosomes were prepared by central composite design (CCD) and characterized for various quality attributes like vesicle shape, size, zeta potential, lamellarity, drug entrapment and drug leaching. The optimized ethosomes were subsequently incorporated int Carbopol® 934 gel and characterized for drug content, rheological behavior, texture profile, in vitro release, ex vivo skin permeation and retention, skin photosensitization and histopathological examination. Ethosomes were found to be spherical and multilamellar in structures having nanometric size range with narrow size distribution, and high encapsulation efficiency. Ethosomal formulations showed significant skin permeation and accumulation in the epidermal and dermal layers. The fluorescence microscopy study using 123 Rhodamine exhibited enhanced permeation of the drug-loaded ethosomes in the deeper layers of skin. Also, the developed formulation showed insignificant phototoxicity and erythema vis-à-vis the conventional cream. The results were cross-validated using histopathological examination of skin segments. In a nutshell, the ethosomes-based hydrogel formulation was found to be a promising drug delivery system demonstrating enhanced percutaneous penetration of methoxsalen with reduced phototoxicity and erythema, thus leading to improved patient compliance for the treatment against vitiligo.     

Vesicular carriers containing phenylethyl resorcinol for topical delivery system; liposomes,transfersomes and invasomes

Topical administration of phenylethyl resorcinol (PR) has attracted much attention as skin lightening agent with potent anti-tyrosinase activity. Two novel types of elastic carriers were developed to overcome the limitation of PR as topical delivery by increasing the solubility, stability and decreasing skin irritation compared to conventional liposomes. In addition, it also promotes skin penetration of PR to reach deep skin layer at the target site. The lead formulations were obtained from the invasomes containing 1% (w/v) d-limonene mixed with 10% (v/v) absolute ethanol as the skin enhancer, and transfersomes containing 15% (w/w) sodium deoxycholate (SDC) as edge activator. All formulations gave a vesicle size < 500 nm, polydispersity index (PDI) < 0.3, high zeta potential, entrapment efficiency > 50%, and good stability on storage at 30°C at 75% RH for 4 months. Transfersomes have a lower degree of deformability (6.63%) than invasomes (25.26%). In contrast, the liposomes as rigid vesicles do not show a deformable property. This characteristic affects the skin permeation, and thus, transfersomes with high elastic property provided a significantly higher cumulative amount, steady state flux (J_ss) and permeability coefficient (K_p) compared to other formulations. However, in vitro PR accumulation in full-thickness newborn pig skin demonstrated that the application of elastic carrier formulations gave significantly higher accumulation than liposomes, and gave anti-tyrosinase activity up to 80%. These results are straightforwardly related to the results of cellular level study. Transfersomes and invasomes showed higher tyrosinase inhibition activity and melanin content reduction when compared to liposomes in B16 melanoma cells. In addition, acute irritation test in rabbits confirmed that these formulations are safe for skin application. Therefore, elastic vesicle carriers have the efficiency to deliver PR into the deep skin in both quantity and effectiveness which are better than conventional liposomes and appropriate for a skin lightening product.     

Formulation and characterization of Phospholipon 90 G and tween 80 based transfersomes for transdermal delivery of eprosartan mesylate

The objective of the current study was to formulate the eprosartan mesylate loaded transfersomes using different proportions of Phospholipon^® 90?G and Tween^® 80 (95–75:5–25% w/w). The prepared transfersomes were characterized for their vesicles size, shape, polydispersity index, zeta potential, entrapment efficiency, in vitro skin permeation, confocal laser scanning microscopy, and in vivo skin irritation. Results revealed that the formulated transfersomes were negatively charged, spherical unilamellar structure of 71.18–85.66?nm with entrapment efficiency of 83.00–88.19%, and presented transdermal flux of 1.78–5.02?μg/cm²/h across rat skin. Confocal laser scanning microscopy confirmed that the formulated rhodamine 6?G loaded transfersomes could penetrate deeply and uniformly into rat skin. Additionally, in vivo skin irritation studies revealed that the prepared transfersomes were devoid of any skin irritation potential (erythema and edema). Results of this study revealed that the transfersomes prepared with Tween^® 80 could be used to enhance the transdermal delivery of eprosartan mesylate. In conclusion, transdermal transfersomes formulation may prove to be an encouraging drug carrier for eprosartan mesylate and other actives, particularly owing to their simple formulation and unsophisticated scale-up methods.     

Nanosized ethosomes bearing ketoprofen for improved transdermal delivery

The potential of ethosomes for delivering ketoprofen via skin was evaluated. The ethosomes were prepared, optimized and characterized. Vesicular shape, size and entrapment efficiency were determined by transmission electron microscopy, dynamic light scattering and minicolumn centrifugation technique, respectively. Vesicle sizes varied from 120.3±6.1 to 410.2±21.8 nm depending on the concentrations of soya phosphatidyl choline (SPC) and ethanol. Entrapment efficiency increased with concentrations of SPC and ethanol. The formulations exhibited entrapment efficiencies of 42–78%. In vitro release through cellophane membrane showed sustained release of drug from ethosomal formulations in contrast to hydroalcoholic drug solution (HA), which released most of the drug within 2–3 h. In vitro drug permeation across human skin revealed improved drug permeation and higher transdermal flux with ethosomal formulations compared to hydroethanolic drug solution. Kinetics of in vitro skin permeation showed zero order drug release from formulations. Based on in vitro transdermal flux, the estimated steady state in vivo plasma concentration from ethosomes attained therapeutic drug levels whereas hydroalcoholic drug solution exhibited sub therapeutic drug concentration with a patch size of 50 cm². Skin permeation of ethosomal formulations assessed by confocal microscopy revealed enhanced permeation of Rhodamine 123 loaded formulation in comparison to the hydroalcoholic solution.     

Nanovesicular carriers as alternative drug delivery systems: ethosomes in focus

Introduction: The application of vesicular carrier formulations has generated promise of overcoming some problems associated with drug delivery arising from not only the physicochemical properties of the drug but also those of the biological barriers, such as the membrane linings of various body tissues and the skin. This review article discusses the importance of various vesicular carriers, namely liposomes, niosomes, transfersomes and ethosomes in drug delivery with greater emphasis on ethosomes.

Areas covered: The nature, mechanism of drug delivery, methods of preparation as well as characterization of vesicular carriers was discussed with a focus on ethosomes. An overview of their potential applications was provided with discussions on the future prospects and challenges of achieving enhanced drug delivery using ethosomes.

Expert opinion: Vesicular carriers offer controlled and sustained drug release, improved permeability and protection of the encapsulated bioactives. Ethosomes offer more efficient and enhanced bioavailability better than the older dosage forms owing to the high ethanol content. Ethosomes have potential applications in the development of nanomedicines, including phytomedicines, for the treatment of challenging diseases ravaging the world today. The future holds great prospects in the utilization of vesicular carriers, especially ethosomes, in overcoming peculiar problems of drug delivery.     

局部用辣椒碱传递体的制备及体内外评价

目的制备辣椒碱传递体，并评价其体内外皮肤渗透性。方法采用高剪切分散乳化均质机制备辣椒碱传递体，并对其大小与结构、包封率、释放度、体外皮肤渗透性和在大鼠组织的分布进行评价。结果辣椒碱传递体结构为小单室泡囊，平均粒径150.6 nm。包封率随脂质浓度增加而增加，当脂质浓度为8%时，包封率为96.7%。体外累积释放量随接受液中乙醇浓度的提高而增加，不同基质大鼠腹部皮肤体外辣椒碱累积透皮量为：传递体>霜剂和混悬液。不同种类皮肤辣椒碱累积透皮量为：小鼠>大鼠>人，人体皮肤辣椒碱累积透皮量为：表皮膜>真皮层和完整皮肤。辣椒碱注射液对大鼠腹腔多次注射体内分布为：骨头>血液>皮肤>肌肉，辣椒碱传递体大鼠腿部局部多次给药，体内分布为：骨头>皮肤>血液>肌肉。结论辣椒碱传递体包封率达到药典的规定(>80%)，辣椒碱传递体可以增加辣椒碱的皮肤透过性，皮肤种类及皮肤的不同层次影响辣椒碱传递体的皮肤透过性。多次注射及局部给药，辣椒碱在骨头及肌肉的分布类似，但在血液及皮肤的分布有所不同。     

Anti-aging formulation of rosmarinic acid-loaded ethosomes and liposomes

The study was aimed to evaluate the effectiveness of rosmarinic acid (RA) loaded ethosomes (ETHs) and liposomes (LPs) when subjected to the transdermal application. RA-loaded ETHs and LPs were prepared, optimised, and characterised. The ex vivo permeation studies of formulations using mouse abdominal skin were performed. Antioxidant activities and the inhibitory effects of formulations on collagenase and elastase enzymes were measured. Optimised ethosomal formulation (F3) was showed nanometric size range (138?±?1.11?nm) and greatest entrapment (55?±?1.80%), was selected for further transdermal permeation studies. Skin permeation profile of the nanoformulations analysed by HPLC revealed an enhanced permeation of ETHs. Transdermal flux of ETHs was found to be higher than RA solution and LPs. Enzyme inhibitions of ETHs were the significant difference found between ETHs and LPs (p?<?0.05). ETHs were found to be more effective and successful than LPs. Results suggest that ETHs are more effective than LPs for transdermal delivery of RA.     

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

The purpose of this study is to characterize a novel transdermal delivery carrier, ethosomes containing 5-fluorouracil. The delivery of drugs from ethosomes in human hypertrophic scar (HS) and the mechanisms of action of ethosomes in human HS were investigated. Percutaneous ethosome permeation was evaluated in vitro in human HS and skin using a Franz's cell. The amount of 5-fluorouracil that permeated HS and skin after 24 hours was most abundant in ethosomes via HS (E-Scar), followed by hydroethanolic solution via HS (H-Scar), ethosomes via skin (E-Skin), and hydroethanolic solution via skin (H-Skin). The penetration of ethosomes in HS and skin was analyzed by ethosomes fluorescently labeled with rhodamine 6GO using confocal laser scanning microscopy. The fluorescence intensity after application for 24 hours was highest in E-Scar, followed by E-Skin, H-Scar, and H-Skin, which indicates the penetration of ethosomes in HS was greatest. In conclusion, we consider that ethosomes are a highly efficient carrier in HS.     

Novel elastic membrane vesicles (EMVs) and ethosomes-mediated effective topical delivery of aceclofenac: a new therapeutic approach for pain and inflammation

Context: Aceclofenac (ACE) is a systematically designed drug, developed to circumvent the concerns associated with diclofenac. But ACE is also associated with non-steroidal anti-inflammatory drug (NSAIDs)-tagged side effects, although of decreased amplitude.

Objective: The present study aims to develop phospholipid-based vesicles (elastic membrane vesicles; EMV and ethosomes) loaded with ACE and explore their potential in topical delivery.

Methods: Elastic membrane vesicles (EMVs) were prepared by thin-film hydration method and ethosomes by cold method. The composition of both the vesicular systems was selected on the basis of vesicle density and drug entrapment. The developed systems were characterized for micromeritics, surface charge, drug entrapment, and morphology. Ex vivo permeation and retention studies on Laca mice skin were performed. In vivo pharmacodynamic evaluation was performed by tail-flick method and carrageenan-induced rat paw-edema model. During stability studies, percent drug leakage was studied.

Results: The selected ratios of phospholpid:drug:stearylamine for EMVs and ethosomes were 8:1:1 and 3:1:1, respectively. The ethosomes were found to offer more vesicle density, drug loading, and deformability index as compared with that of EMVs. The drug permeation and the retention offered by both the vesicular systems were superior to that of the conventional cream; however, performance of ethosomes superseded that of EMVs. The phospholipid-based vesicles were found to be well tolerated on mice skin. Although, the in vivo performance of ethosomes was found to be better than that of EMVs in both the studied models.

Conclusion: The phospholipid-based vesicular systems, especially, ethosomes can be a promising tool to enhance the delivery and safety of ACE by topical route.     

The application of anethole,menthone, and eugenol in transdermal penetration of valsartan: Enhancement and mechanistic investigation

Context: The main barrier for transdermal delivery is the obstacle property of the stratum corneum. Many types of chemical penetration enhancers have been used to breach the skin barrier; among the penetration enhancers, terpenes are found as the most highly advanced, safe, and proven category.

Objective: In the present investigation, the terpenes anethole, menthone, and eugenol were used to enhance the permeation of valsartan through rat skin in vitro and their enhancement mechanism was investigated.

Materials and methods: Skin permeation studies of valsartan across rat skin in the absence and the presence of terpenes at 1% w/v, 3% w/v, and 5% w/v in vehicle were carried out using the transdermal diffusion cell sampling system across rat skin and samples were withdrawn from the receptor compartment at 1, 2, 3, 4, 6, 8, 10, 12, and 24?h and analysed for drug content by the HPLC method. The mechanism of skin permeation enhancement of valsartan by terpenes treatment was evaluated by Fourier transform infrared spectroscopy (FTIR) analysis and differential scanning calorimetry (DSC).

Results: All the investigated terpenes provided a significant (p?<?0.01) enhancement in the valsartan flux at a concentration of 1%, and less so at 3% and 5%. The effectiveness of terpenes at 1% concentration was in the following order: anethole?>?menthone?>?eugenol with 4.4-, 4.0-, and 3.0-fold enhancement ratio over control, respectively. DSC study showed that the treatment of stratum corneum with anethole shifted endotherm down to lower melting point while FTIR studies revealed that anethole produced maximum decrease in peak height and area than other two terpenes.

Conclusion: The investigated terpenes can be successfully used as potential enhancers for the enhancement of skin permeation of lipophilic drug.     

根皮素醇质体的制备、表征及对体外透皮吸收的影响

目的：制备根皮素醇质体,考察醇质体作为根皮素经皮给药载体的可行性。方法：乙醇注入法制备根皮素醇质体。采用包封率和粒径为考察指标,正交试验优化大豆磷脂用量、胆固醇用量、乙醇体积及水浴温度。测定根皮素醇质体粒径分布、多分散指标和Zeta电位,采用Franz扩散池比较根皮素及其醇质体体外透皮特征。结果：根皮素醇质体最佳处方工艺：磷脂用量为220 mg、胆固醇用量为14 mg、乙醇体积为5 mL、水浴温度为40℃,根皮素醇质体平均包封率为（83.09±1.24）%,载药量为（4.86±0.89）%,粒径为（162.19±5.88） nm,PDI为（0.067±0.011）;Zeta电位为（-15.09±2.16） mV。根皮素以醇质体形式给药后单位累积透过量提高了3.43倍,且渗透过程符合零级动力学。结论：醇质体具有包封率高,粒径分布均匀等特点,可提高根皮素的渗透速率和经皮渗透量,值得进一步研究。     

Effect of cholesterol and ethanol on dermal delivery from DPPC liposomes

The main objective of the present work was to compare the dermal delivery of minoxidil (Mx), a lipophilic drug from ethosomes versus classic liposomes, containing different cholesterol (CHOL) concentrations. All the systems were characterized for shape, lamellarity, particle size and entrapment efficiency percentage (EE), by transmission electron microscopy (TEM), confocal laser scanning microscopy (CLSM), laser diffraction and ultracentrifugation or dialysis methods, respectively. Multilamellar vesicles (MLVs) were obtained and one to six lamellae were visualized by CLSM. The presence of ethanol in the formulations affects the particle size in terms of reducing this parameter. In addition, it was possible to appreciate the influence of CHOL on the vesicle size, because it was increased, as CHOL concentration was higher. When the EE was determined by two different methods (ultracentrifugation and dialysis methods), a clear losing of entrapped drug by the ultracentrifugation method was observed, because the strong energy transmitted to the samples disrupted vesicles. Vesicles were non-occlusively applied on rat skin and the permeation pattern of the different systems, depth into the skin and the main permeation pathway were studied by using beta-carotene as a fluorescent probe. CLSM studies showed that ethosomal systems were much more efficient at delivering the fluorescent substance into the skin in terms of quantity and depth, than either liposomes or hydroalcoholic solutions.