新的药物传递系统:外泌体作为药物载体递送*

外泌体(exosomes)是细胞分泌的囊泡,在细胞与细胞之间通信中发挥重要作用。由于其固有的长距离通信能力和出色的生物相容性而具有很大的潜力作为药物递送载体,尤其适合递送蛋白质、核酸、基因治疗剂等治疗药物。许多研究表明外泌体可以有效地将许多不同种类的货物递送至靶细胞,因此,它们常被作为药物载体用于治疗。对外泌体作为药物递送系统中面临的外泌体分离,药物装载和靶向治疗应用的进展与挑战作一介绍,以期更好为外泌体药物递送系统开发提供新思路。     

新的药物传递系统:外泌体作为药物载体递送*

外泌体(exosomes)是细胞分泌的囊泡,在细胞与细胞之间通信中发挥重要作用。由于其固有的长距离通信能力和出色的生物相容性而具有很大的潜力作为药物递送载体,尤其适合递送蛋白质、核酸、基因治疗剂等治疗药物。许多研究表明外泌体可以有效地将许多不同种类的货物递送至靶细胞,因此,它们常被作为药物载体用于治疗。对外泌体作为药物递送系统中面临的外泌体分离,药物装载和靶向治疗应用的进展与挑战作一介绍,以期更好为外泌体药物递送系统开发提供新思路。     

经皮给药载体载MD-CPT透明质酸纳米乳的细胞吞噬与体内药代动力学研究

本文在研究制备了包载10,11-亚甲二氧基喜树碱(MD-CPT)的透明质酸纳米乳(HANs)经皮给药系统的基础上,进一步研究了载MD-CPT透明质酸纳米乳的细胞吞噬,并进行了体内药代动力学分析.通过优化制备条件,得到了皮肤渗透性良好的缓释剂型.从CLSM观察到药物被细胞摄入并传递入细胞核,同时,载药纳米乳的细胞吞噬效率呈时间依赖性,不同细胞株HSF、HUVES、MCF-7、KF的细胞吞噬率略有不同.用Rhodanmine B标记HANs,通过荧光显微镜观察到载药纳米乳透过角质层到达真皮层的拟动态过程.利用HPLC检测MD-CPT血药浓度,测得经皮给药半衰期T1/2是静脉注射的3.6倍,肌肉注射的1.6倍,体内药物滞留时间显著增加;血药浓度峰谷值差异小,曲线平缓,说明经皮给药能保证血药浓度呈现可控的持续性.最终通过活体成像系统和组织切片荧光显微镜,直观地反映出经皮给药后药物在大鼠体内的分布情况和各组织器官药物含量,确定载药纳米乳主要采取胞间渗透的扩散方式,在局部给药的区域滞留时间较长,有利于对浅表性的病灶区持续给药,延长药效,而剩余的MD-CPT和解离的HANs都进入了血液循环,最终通过新陈代谢被排出体外.为无创型HANs经皮给药系统应用于浅表性肿瘤治疗提供了理论基础.     

Nanocarrier for the Transdermal Delivery of an Antiparkinsonian Drug

The purpose of the present study was to investigate the potential of nanoemulsions as nanodrug carrier systems for the percutaneous delivery of ropinirole. Nanoemulsions comprised Capryol 90 as the oil phase, Tween 20 as the surfactant, Carbitol as the cosurfactant, and water as an external phase. The effects of composition of nanoemulsion, including the ratio of surfactant and cosurfactant (S _mix) and their concentration on skin permeation, were evaluated. All the prepared nanoemulsions showed a significant increase in permeation parameters such as steady state flux (J _ss) and permeability coefficient (K _p) when compared to the control (p < 0.01). Nanoemulsion composition (NEL3) comprising ropinirole (0.5% w/w), Capryol 90 (5% w/w), S _mix 2:1 (35% w/w), and water (59.5% w/w) showed the highest flux (51.81 ± 5.03 μg/cm²/h) and was selected for formulation into nanoemulsion gel. The gel was further optimized with respect to oil concentration (Capryol 90), polymer concentration (Carbopol), and drug content by employing the Box–Behnken design, which statistically evaluated the effects of these components on ropinirole permeation. Oil and polymer concentrations were found to have a negative influence on permeation, while the drug content had a positive effect. Nanoemulsion gel showed a 7.5-fold increase in skin permeation rate when compared to the conventional hydrogel. In conclusion, the results of the present investigation suggested a promising role of nanoemulsions in enhancing the transdermal permeation of ropinirole.     

Characterization of Polymeric Microneedle Arrays for Transdermal Drug Delivery

Microfabrication of dissolvable, swellable, and biodegradable polymeric microneedle arrays (MNs) were extensively investigated based in a nano sensitive fabrication style known as micromilling that is then combined with conventional micromolding technique. The aim of this study was to describe the polymer selection, and optimize formulation compounding parameters for various polymeric MNs. Inverse replication of micromilled master MNs reproduced with polydimethylsiloxane (PDMS), where solid out of plane polymeric MNs were subsequently assembled, and physicochemically characterized. Dissolvable, swellable, and biodegradable MNs were constructed to depth of less than 1 mm with an aspect ratio of 3.6, and 1/2 mm of both inter needle tip and base spacing. Micromolding step also enabled to replicate the MNs very precisely and accurate. Polymeric microneedles (MN) precision was ranging from ±0.18 to ±1.82% for microneedle height, ±0.45 to ±1.42% for base diameter, and ±0.22 to ±0.95% for interbase spacing. Although dissolvable sodium alginate MN showed less physical robustness than biodegradable polylactic-co-glycolic acid MN, their thermogravimetric analysis is of promise for constructing these polymeric types of matrix devices.     

Fabrication of Tip-Dissolving Microneedles for Transdermal Drug Delivery of Meloxicam

Dissolving microneedles (MNs) offered a simple, minimally invasive method for meloxicam (MX) delivery to the skin. However, the fabrication of dissolving MNs still faced some challenges, such as significant time consumption, loss of drug activity, and difficulty in regulating MN drug loading. To address these issues, we developed the tip-dissolving (TD) MNs. Several kinds of drugs were encapsulated successfully, and the quantity of MX ranged from 37.23?±?8.40 to 332.53?±?13.37 μg was precisely controlled. The effects of fabrication process on biomacromolecules stability were studied, and it was found that tyrosinase kept 90.4% activity during the fabrication process. The whole process for the fabrication of MNs only takes approximately 1 h. In order to further evaluate the potential of the TD MNs, MX TD MNs were prepared for in vitro release experiments, in vivo release experiments, safety evaluation, pharmacokinetic studies, and pharmacodynamic studies. The results demonstrated that MX TD MNs offered several advantages, including rapid release of the encapsulated drug (91.72% within 30 min), efficient drug delivery to skin (79.18%), no obvious skin irritation, decent relative bioavailability (122.3%), and strong anti-inflammatory and analgesic effects. Based on these results, we envisage that the TD MNs have promising potential for transdermal drug delivery of MX.     

Preparation of Cationic Immunovesicles Containing Cationic Peptide Lipid for Specific Drug Delivery to Target Cells

The cationic vesicle composed of Span80 and cationic peptide lipid (CPL) was prepared. The cytotoxicity of the Span80-CPL cationic vesicle was very low compared with Span80 vesicle. Antibody was able to be immobilized on vesicle surface by mediation of protein A. The antigen targeting ability of the antibody-immobilized vesicle (immunovesicle) derived from antibody was evaluated. Our results suggested that the Span80-CPL immunovesicles specifically associate with target cells by the antibody mediation, and the substance capsulated in immunovesicle was transferred into the target cells. This means that the Span80-CPL immunovesicle is expected to achieve a high local concentration of an encapsulated drug at the target.     

经皮给药系统产业化开发的关键问题探讨

以经皮给药系统的开发及产业化为主体思路,在对经皮给药系统发展现状认识的基础上,重点对经皮给药产品研发中的吸收模型 及体内外相关性评价研究、产业化设备、国内外研发模式等进行初步探讨,分析经皮给药系统开发中存在的问题和挑战并提出相应的解 决方案,以期为今后国内经皮给药制剂的发展提供思路。     

Transdermal Delivery of a Tetrapeptide: Evaluation of Passive Diffusion

Skin penetration of the tetrapeptide Ac-Ala-Ala-Pro-Val-NH₂ was assessed. This peptide sequence fits the P-P₁ subsites of elastase and inhibits human neutrophil elastase competitively. Consequently this peptide may be therapeutically useful in a variety of inflammatory disorders, including psoriasis, in which elevated levels of human neutrophil elastase have been reported. Peptide penetration was assessed across whole human skin, whole skin with the stratum corneum removed by tape stripping and epidermis, which had been removed from the dermis by heat separation. The influence of 75 aqueous ethanol as a potential penetration enhancer of the tetrapeptide across epidermis was also assessed. The tetrapeptide did not penetrate whole human skin or epidermis, even under the influence of 75 aqueous ethanol. However, when the stratum corneum was removed tetrapeptide flux of 73.39 μg cm² h⁻¹ was achieved. The study demonstrates that the stratum corneum is the main barrier to tetrapeptide skin penetration and must be overcome if therapeutically relevant amounts of tetrapeptide are to be delivered to the skin.     

Transdermal Delivery of Proteins

Transdermal delivery of peptides and proteins avoids the disadvantages associated with the invasive parenteral route of administration and other alternative routes such as the pulmonary and nasal routes. Since proteins have a large size and are hydrophilic in nature, they cannot permeate passively across the skin due to the stratum corneum which allows the transport of only small lipophilic drug molecules. Enhancement techniques such as chemical enhancers, iontophoresis, microneedles, electroporation, sonophoresis, thermal ablation, laser ablation, radiofrequency ablation and noninvasive jet injectors aid in the delivery of proteins by overcoming the skin barrier in different ways. In this review, these enhancement techniques that can enable the transdermal delivery of proteins are discussed, including a discussion of mechanisms, sterility requirements, and commercial development of products. Combination of enhancement techniques may result in a synergistic effect allowing increased protein delivery and these are also discussed.     

Preparation and Evaluation of Diltiazem Hydrochloride Diffusion-Controlled Transdermal Delivery System

The objective was to investigate the suitable polymeric films for the development of diltiazem hydrochloride (diltiazem HCl) transdermal drug delivery systems. Hydroxypropyl methylcellulose (HPMC) and ethylcellulose (EC) were used as hydrophilic and hydrophobic film formers, respectively. Effects of HPMC/EC ratios and plasticizers on mechanical properties of free films were studied. Effects of HPMC/EC ratios on moisture uptake, in vitro release and permeation through pig ear skin of diltiazem HCl films were evaluated. Influence of enhancers including isopropyl myristate (IPM), isopropyl palmitate (IPP), N-methyl-2-pyrrolidone, oleic acid, polyethylene glycol 400, propylene glycol, and Tween80 on permeation was evaluated. It was found that addition of EC into HPMC film produced lower ultimate tensile strength, percent elongation at break and Young’s modulus, however, addition of EC up to 60% resulted in too hard film. Plasticization with dibutyl phthalate (DBP) produced higher strength but lower elongation as compared to triethyl citrate. The moisture uptake and initial release rates (0–1 h) of diltiazem HCl films decreased with increasing the EC ratio. Diltiazem HCl films (10:0, 8:2 and 6:4 HPMC/EC) were studied for permeation because of the higher release rate. The 10:0 and 8:2 HPMC/EC films showed the comparable permeation-time profiles, and had higher flux values and shorter lag time as compared to 6:4 HPMC/EC film. Addition of IPM, IPP or Tween80 could enhance the fluxes for approx. three times while Tween80 also shorten the lag time. In conclusion, the film composed of 8:2 HPMC/EC, 30% DBP and 10% IPM, IPP or Tween80 loaded with 25% diltiazem HCl should be selected for manufacturing transdermal patch by using a suitable adhesive layer and backing membrane. Further in vitro permeation and in vivo performance studies are required.     

Nanostructured Lipid Carriers (NLC) for Parenteral Delivery of an Anticancer Drug

The purpose of this research was to formulate nanostructured lipid carriers (NLC) for the parenteral delivery of an anticancer drug, all-trans retinoic acid (ATRA). The ATRA was incorporated into NLC by the de novo emulsification method. The effect of the formulation factor, i.e., type and oil ratio, initial ATRA concentration on physicochemical properties was determined. The anticancer efficacy of ATRA-loaded NLC on HL-60 and HepG2 cells was also studied. NLC was formulated using a blend of solid lipids (cetyl palmitate) and liquid lipids (soybean oil (S), medium-chain triglyceride (M), S/oleic acid (O; 3:1) and M/O (3:1)) at a weight ratio of 1:1. ATRA-loaded NLC had an average size of less than 200 nm (141.80 to 172.95 nm) with a narrow PDI and negative zeta potential that was within an acceptable range for intravenous injection. The results indicated that oleic acid enhanced the ATRA-loading capacity of NLC. In vitro ATRA release was only approximately 4.06% to 4.34% for 48 h, and no significant difference in ATRA release rate from all NLC formulations in accordance with the composition of the oil phase. Moreover, no burst release of the drug was observed, indicating that NLC could prolong the release of ATRA. The initial drug concentration affected the photodegradation rate but did not affect the release rate. All ATRA-loaded NLC formulations exhibited the photoprotective property. The cytotoxicity results showed that all ATRA-loaded NLC had higher cytotoxicity than the free drug and HL-60 cells were more sensitive to ATRA than HepG2 cells.     

Effect of Adhesive Layer Thickness and Drug Loading on Estradiol Crystallization in a Transdermal Drug Delivery System

The effects of adhesive layer thickness and drug loading on estradiol crystallization were studied in a drug-in-adhesive patch. Patches containing different estradiol loadings (1.1% and 1.6% w/w) in different thicknesses (45, 60, and 90 μm) were prepared by coating of a homogenous mixture of adhesive solution and the drug on a siliconized release liner by a film applicator. After drying, the film was laminated on a Poly(ethylene terephthalate) backing layer and cut into appropriate size. Release tests were performed using thermostated Chien-type diffusion cells. Cross-section of the patches was observed by optical microscopy. Scanning electron microscopy was done for surface analysis of the patches after drug release test. Crystal formation was not expected in the adhesive layer based on the linear free-energy relationship formalisms however; crystalline regions were observed in different locations through the thickness of the patches. These regions were significantly more discontinuous in 45 μm samples which elucidated the effective role of adhesive layer thickness in drug crystallization. Extensive crystallization observed for thicker patches was attributed to the strong crosslinking capability of estradiol hemihydrate. Drug release study confirmed some of the crystallization results. No significant increase was observed in the burst release with increasing in thickness from 45 to 60 μm which can be attributed to the severe increase in the crystallization extent. Also, formation of a crystalline layer near the releasing surface and more discontinuous pattern of the crystals in some samples was confirmed by investigation of the drug release curves.     

Design,Synthesis of Novel Lipids as Chemical Permeation Enhancers and Development of Nanoparticle System for Transdermal Drug Delivery

In the present study, we designed and developed novel lipids that include (Z)-1-(Octadec-9-en-1-yl)-pyrrolidine (Cy5T), 1, 1-Di-((Z)-octadec-9-en-1-yl)pyrrolidin-1-ium iodide (Cy5), (Z)-1-(Octadec-9-en-1-yl)-piperidine (Cy6T), and 1, 1-Di-((Z)-octadec-9-en-1-yl) piperidin-1-ium iodide (Cy6) to enhance the transdermal permeation of some selected drugs. Firstly, we evaluated the transdermal permeation efficacies of these lipids as chemical permeation enhancers in vehicle formulations for melatonin, ß-estradiol, caffeine, α-MSH, and spantide using franz diffusion cells. Among them Cy5 lipid was determined to be the most efficient by increasing the transdermal permeation of melatonin, ß-estradiol, caffeine, α-MSH, and spantide by 1.5 to 3.26-fold more at the epidermal layer and 1.3 to 2.5-fold more at the dermal layer, in comparison to either NMP or OA. Hence we developed a nanoparticle system (cy5 lipid ethanol drug nanoparticles) to evaluate any further improvement in the drug penetration. Cy5 lipid formed uniformly sized nanoparticles ranging from 150–200 nm depending on the type of drug. Further, Cy5 based nanoparticle system significantly (p<0.05) increased the permeation of all the drugs in comparison to the lipid solution and standard permeation enhancers. There were about 1.54 to 22-fold more of drug retained in the dermis for the Cy5 based nanoparticles compared to OA/NMP standard enhancers and 3.87 to 66.67-fold more than lipid solution. In addition, epifluorescent microscopic analysis in rhodamine-PE permeation studies confirmed the superior permeation enhancement of LEDs (detection of fluorescence up to skin depth of 340 μm) more than lipid solution, which revealed fluorescence up to skin depth of only 260 μm. In summary the present findings demonstrate that i) cationic lipid with 5 membered amine heterocyclic ring has higher permeating efficacy than the 6 membered amine hertocyclic ring. ii) The nanoparticle system prepared with Cy5 showed significant (p<0.05) increase in the permeation of the drugs than the control penetration enhancers, oleic acid and NMP.     

Elastic Vesicles as a Tool for Dermal and Transdermal Delivery

The main problem in delivery of drugs across the skin is the barrier function of the skin, which is located in the outermost layer of the skin, the stratum corneum. The stratum corneum consists of corneocytes surrounded by lipid layers, the so-called lipid lamellae. When applying drugs onto the skin, the major penetration pathway is the tortuous intercellular route along the lipid lamellae. In order to increase the number of drugs administered via the transdermal route, novel drug delivery systems have to be designed. Among these systems are iontophoresis, electroporation, microneedles, and vesicular systems.     

Microcapsules and Transdermal Patch: A Comparative Approach for Improved Delivery of Antidiabetic Drug

Glibenclamide (GL)-loaded microcapsules (MC) and transdermal patches (TDP) were formulated and in vitro and in vivo parameters compared to find out the best route of drug administration. The formulation TDP1 having a drug–polymer ratio 1:1 showed comparatively higher GL release and better permeation across mice skin (p < 0.05). From the comparative study, it was concluded that the transdermal system of GL produced better improvement compared to oral microcapsule administration (p < 0.05). The transdermal system exhibited comparatively slow and continuous supply of GL at a desired rate to systemic circulation avoiding metabolism, which improved day-to-day glycemic control in diabetic subjects. Transdermal system of GL exhibited better control of hyperglycemia and prolonged plasma half-life by transdermal systems (9.6 ± 1.2 h) in comparison with oral microcapsule (5.84 ± 2.1 h), indicating that the drug, when administered by transdermal systems, will remain in the body for a longer period. From the glucose tolerance test, transdermal route effectively maintained the normoglycemic levels in contrast to the oral group (MC1), which produced remarkable hypoglycemia ranging from −12.6 ± 2.1% to −18 ± 2.3%. The significantly high (p < 0.05) area under the curve values observed with transdermal system (1,346.2 ± 92.3 ng ml⁻¹ h⁻¹) also indicate increased bioavailability of the drug from these systems compared to the oral route (829.8 ± 76.4 ng ml⁻¹ h⁻¹).     

外泌体作为疾病诊断标志物及药物载体的应用前景

作为一种纳米级别的囊泡,外泌体的相关研究近年来逐渐成为热点。外泌体来源于细胞内的多囊泡胞内体,经由细胞膜释放到细胞外。由于来自特定细胞类型的外泌体含有多种特异性的蛋白质和microRNA,使其成为了可以广泛用于疾病诊断及预后的新型生物标志物。相较于其他外源性药物载体,外泌体具有更低的免疫原性,并能够靶向作用于病变细胞。这使得由细胞天然产生或经过人工改造的外泌体作为一种新兴的药物载体具有良好的发展前景。特别是近几年,外泌体在临床应用领域的发展潜力不断获得拓展,针对肿瘤、糖尿病、心脑血管疾病、神经退行性病变等重大疾病,以外泌体为基础的疾病诊断和药物的研发都取得了快速的进步。本篇综述重点介绍了外泌体作为一种生物标志物在疾病诊断和预后中的应用,同时阐述了外泌体作为一种新兴的药物载体所具有的优势以及存在的问题。     

生物可降解聚合物纳米粒给药载体

生物可降解聚合物纳米粒用于给药载体具有广阔的前景。本文综述了生物可降解聚合物纳米粒给药载体领域的最新进展 :包括纳米粒表面修饰特性、药物释放、载多肽和蛋白质等生物大分子药物传输中的潜在应用。     

l-Carvyl Esters as Penetration Enhancers for the Transdermal Delivery of 5-Fluorouracil

To develop effective and safe penetration enhancers, a series of l-carvyl esters, namely, 5-isopropenyl-2-methylcyclohex-2-en-1-yl heptanoate (C-HEP), 5-isopropenyl-2- methylcyclohex-2-en-1-yl octanoate (C-OCT), 5-isopropenyl-2-methylcyclohex-2-en-1-yl decanoate (C-DEC), 5-isopropenyl-2-methylcyclohex-2-en-1-yl dodecanoate (C-DOD), 5-isopropenyl-2-methylcyclohex-2-en-1-yl tetradecanoate (C-TET), and 5-isopropenyl-2-methylcyclohex-2-en-1-yl palmitate (C-PAL), was synthesized from l-carveol and saturated fatty acids (C7–C16). The volatility of l-carveol and l-carvyl esters was evaluated by a live weight loss experiment. The enhancing effects of l-carvyl esters on 5-fluorouracil (FU) were investigated in the in vitro permeation experiment on rat skin. The stratum corneum (SC) uptakes of the enhancers were tested in vitro by gas chromatography. Only the l-carvyl esters with a moderate SC uptake, namely, C-OCT (C8), C-DEC (C10), and C-DOD (C12), showed a potential to enhance FU skin permeation. An evident parabolic relationship was found between the permeation enhancement of FU and the SC uptake of the l-carvyl esters. The l-carvyl esters with a chain length of C8–C12 seemed to be favorable for FU.