Touch-actuated microneedle array patch for closed-loop transdermal drug delivery

To date, only approximately 20 drugs synthesized with small molecules have been approved by the FDA for use in traditional transdermal patches (TTP) owing to the extremely low permeation rate of the skin barrier for macromolecular drugs. A novel touch-actuated microneedle array patch (TMAP) was developed for transdermal delivery of liquid macromolecular drugs. TMAP is a combination of a typical TTP and a solid microneedle array (MA). High doses of liquid drug formulations, especially heat-sensitive compounds can be easily filled and stored in the drug reservoir of TMAPs. TMAP can easily penetrate the skin and automatically retract from it to create microchannels through the stratum corneum (SC) layer using touch-actuated ‘press and release’ actions for passive permeation of liquid drugs. Comparison of subcutaneous injection, TTP, solid MA, and dissolvable MA, indicated that insulin-loaded TMAP exhibited the best hypoglycemic effect on type 1 diabetic rats. A ‘closed-loop’ permeation control was also provided for on-demand insulin delivery based on feedback of blood glucose levels (BGLs). Twenty IU-insulin-loaded TMAP maintained the type 1 diabetic rats in a normoglycemic state for approximately 11.63?h, the longest therapeutic duration among all previously reported results on microneedle-based transdermal patches. TMAP possesses excellent transdermal drug delivery capabilities.     

不锈钢微针经皮给药的研究

目的：将不锈钢微针阵列应用于经皮给药。考察离体大鼠皮肤经不同针形微针预处理相同时间、相同针形微针预处理不同时间后，模型药物鬼臼毒素经大鼠皮肤的透皮能力。方法：微针预处理大鼠皮肤后，用改进的Franz扩散池研究鬼臼毒素对皮肤的透皮速率。高效液相色谱法测定鬼臼毒素的含量。结果：皮肤经微针预处理后进行鬼臼毒素透皮，其透皮速率比未经微针处理时有明显提高。三角形微针、梯形微针、矛形微针对鬼臼毒素的促渗能力依次增强；三者所引起的鬼臼毒素在皮肤中的滞留量有显著差异。同种针形微针预处理皮肤时间越长，鬼臼毒素的透皮速率越大；但微针预处理时间对皮肤中的药物滞留量无显著影响。结论：微针用于药物经皮给药时，微针针形、微针的预处理时间对药物的经皮渗透具有重要影响。     

微针开启透皮释药的一扇新门

透皮控释贴片产品在20年前已开始陆续上市：硝酸甘油贴片治疗心绞痛，东莨菪碱贴片治疗晕动症，可乐定贴片用于降血压，芬太尼贴片控制疼痛，烟碱贴片用来戒烟，雌激素贴片用于激素替代治疗，睾酮贴片治疗男性性腺功能减退，利多卡因贴片局麻和复方雌二醇／地屈孕酮贴片用于避孕……。2003年新上市的奥昔布宁透皮控释贴片用于治疗膀胱活动过度，丁丙诺啡贴片用于镇痛，复方炔雌醇/诺孕曲明贴片用于避孕。这些透皮贴片应用的控释技术主要有固体基质释放系统、膜速率控制储存释放系统和药物储于粘附剂释放系统。     

Enhanced delivery of hydrophilic peptides in vitro by transdermal microneedle pretreatment

The aims of this study were to investigate the utility of solid microneedle arrays (150 µm in length) in enhancing transdermal delivery of peptides and to examine the relationship between peptide permeation rates and D₂O flux. Four model peptides were used (Gly–Gln–Pro–Arg [tetrapeptide-3, 456.6 Da], Val–Gly–Val–Ala–Pro–Gly [hexapeptide, 498.6 Da], AC–Glu–Glu–Met–Gln–Arg–Arg–NH₂ [acetyl hexapeptide-3, 889 Da] and Cys–Tyr–Ile–Gln–Asn–Cys–Pro–Leu–Gly–NH₂ [oxytocin, 1007.2 Da]). The influence of microneedle pretreatment on skin permeation was evaluated using porcine ear skin with Franze diffusion cell. Peptide permeation across the skin was significantly enhanced by microneedle pretreatment, and permeation rates were dependent on peptide molecular weights. A positive correlation between D₂O flux and acetyl hexapeptide-3 clearances suggests that convective solvent flow contributes to the enhanced transdermal peptide delivery. It is concluded that solid microneedle arrays are effective devices to enhance skin delivery of peptides.KEY WORDS: Microneedle, Peptide, Transdermal, Convective solvent flow     

胰岛素相转化水凝胶微针透皮贴片

本研究采用化学惰性、可吸收体液溶涨从玻璃态变为水凝胶态的聚合物材料制备了可用于胰岛素透皮给药的微针贴剂,相转化水凝胶微针贴膜。胰岛素是1型和晚期2型糖尿病的必用药。针尖穿透表皮后吸收体液溶涨,使预先担栽的胰岛素在真皮层高效而精确地释放出来,同时不留下针尖物质在皮层的沉积。上述性质使得相转化水凝胶微针贴膜成为需要一生频繁用药的蛋白、多酞药物的理想剂型。     

胰岛素相转化水凝胶微针透皮贴片

本研究采用化学惰性、可吸收体液溶涨从玻璃态变为水凝胶态的聚合物材料制备了可用于胰岛素透皮给药的微针贴剂,相转化水凝胶微针贴膜。胰岛素是1型和晚期2型糖尿病的必用药。针尖穿透表皮后吸收体液溶涨,使预先担栽的胰岛素在真皮层高效而精确地释放出来,同时不留下针尖物质在皮层的沉积。上述性质使得相转化水凝胶微针贴膜成为需要一生频繁用药的蛋白、多酞药物的理想剂型。     

改装滚轮微针用于醋酸曲安奈德经皮给药的特性试验

目的:评价改装滚轮微针用于曲安奈德经皮给药的力度可控性、释药重现性和皮肤刺激性。方法:改装市售滚轮微针;石蜡切片、HE染色法观察不同微针使用力度(2.5,5.0,7.5,10.0,12.5,15.0,17.5,20.0 N)时的皮肤微孔深度,探讨改装前后其力度可控性;以离体裸鼠皮肤为屏障,Franz扩散池法考察改装前后曲安奈德经皮渗透特性;评分法测定皮肤刺激性。结果:皮肤微孔深度随微针使用力度的增加而加大,微孔深度范围由65.28~106.25 μm收窄为改装后的71.53~97.92 μm,其RSD范围由10.45%~19.69%显著下降至改装后的2.33%~9.21%。在相同微针使用力度下,曲安奈德的累积释药量RSD范围由改装前的34.75%~55.92%,显著下降至改装后的14.29%~29.73%。改装滚轮微针用药1 h时出现轻度皮肤刺激性,之后消失。结论:与市售滚轮微针相比,改装滚轮微针具有较好的力度可控性、释药重现性,以及较小的皮肤刺激性。     

Pharmacokinetics of transdermal drug delivery

The pharmacokinetics of drug delivery from transdermal controlled-release devices consisting of (a) a membrane plus a reservoir or (b) a monolithic slab are examined. For the period when the devices act as if the drug reservoir were infinite, simple relationships for the steady-state slope and time lag are derived and studied. An analysis of the time region when depletion of the finite dose is obtained is used to estimate the useful device lifetime. Applications to patch design are discussed.     

Passive transdermal drug delivery systems

The skin has evolved as a formidable barrier against invasion by external microorganisms and against the prevention of water loss. Notwithstanding this, transdermal drug delivery systems have been designed with the aim of providing continuous controlled delivery of drugs via this barrier to the systemic circulation. There are numerous systems now available that effectively deliver drugs across the skin. These include reservoir devices, matrix diffusion-controlled devices, multiple polymer devices, and multilayer matrix systems. This review article focuses on the design characteristics and composition of the main categories of passive transdermal delivery device available. Mechanisms controlling release of the active drug from these systems as well as patch size and irritation problems will be considered. Recent developments in the field are highlighted including advances in patch design as well as the increasing number of drug molecules now amenable to delivery via this route. From the early complex patch designs, devices have now evolved towards simpler, matrix formulations. One of the newer technologies to emerge is the delivery-optimized thermodynamic (DOT) patch system, which allows greater drug loading to be achieved in a much smaller patch size. With the DOT technology, drug is loaded in an acrylic-based adhesive. The drug/acrylic blend is dispersed through silicone adhesive, creating a semi-solid suspension. This overcomes the problem with conventional drug-in-adhesive matrix patches, in which a large drug load in the adhesive reservoir can compromise the adhesive properties or necessitate a large patch size. Transdermal drug delivery remains an attractive and evolving field offering many benefits over alternative routes of drug delivery. Future developments in the field should address problems relating to irritancy and sensitization, which currently exclude a number of therapeutic entities from delivery via this route. It is likely that further innovations in matrix composition and formulation will further expand the number of candidate drugs available for transdermal delivery.     

Transfersomes for transdermal drug delivery

Transfersomes (Idea AG) are a form of elastic or deformable vesicle, which were first introduced in the early 1990s. Elasticity is generated by incorporation of an edge activator in the lipid bilayer structure. The original composition of these vesicles was soya phosphatidyl choline incorporating sodium cholate and a small concentration of ethanol. Transfersomes are applied in a non-occluded method to the skin and have been shown to permeate through the stratum corneum lipid lamellar regions as a result of the hydration or osmotic force in the skin. They have been used as drug carriers for a range of small molecules, peptides, proteins and vaccines, both in vitro and in vivo. It has been claimed by Idea AG that intact Transfersomes penetrate through the stratum corneum and the underlying viable skin into the blood circulation. However, this has not been substantiated by other research groups who have extensively probed the mechanism of penetration and interaction of elastic vesicles in the skin. Structural changes in the stratum corneum have been identified, and intact elastic vesicles visualised within the stratum corneum lipid lamellar regions, but no intact vesicles have been ascertained in the viable tissues. Using the principle of incorporating an edge-activator agent into a bilayer structure, a number of other elastic vesicle compositions have been evaluated. This review describes the research into the development and evaluation of Transfersomes and elastic vesicles as topical and transdermal delivery systems.     

Ultrasound and transdermal drug delivery

Transdermal drug delivery offers an attractive alternative to the conventional drug delivery methods of oral administration and injection. However, the stratum corneum acts as a barrier that limits the penetration of substances through the skin. Application of ultrasound to the skin increases its permeability (sonophoresis) and enables the delivery of various substances into and through the skin. This review presents the main findings in the field of sonophoresis, namely transdermal drug delivery and transdermal monitoring. Particular attention is paid to proposed enhancement mechanisms and future trends in the field of cutaneous vaccination and gene delivery.     

Reflections on transdermal drug delivery

'It is better to be approximately right rather than precisely wrong.'     

Microneedles for transdermal drug delivery

The success of transdermal drug delivery has been severely limited by the inability of most drugs to enter the skin at therapeutically useful rates. Recently, the use of micron-scale needles in increasing skin permeability has been proposed and shown to dramatically increase transdermal delivery, especially for macromolecules. Using the tools of the microelectronics industry, microneedles have been fabricated with a range of sizes, shapes and materials. Most drug delivery studies have emphasized solid microneedles, which have been shown to increase skin permeability to a broad range of molecules and nanoparticles in vitro. In vivo studies have demonstrated delivery of oligonucleotides, reduction of blood glucose level by insulin, and induction of immune responses from protein and DNA vaccines. For these studies, needle arrays have been used to pierce holes into skin to increase transport by diffusion or iontophoresis or as drug carriers that release drug into the skin from a microneedle surface coating. Hollow microneedles have also been developed and shown to microinject insulin to diabetic rats. To address practical applications of microneedles, the ratio of microneedle fracture force to skin insertion force (i.e. margin of safety) was found to be optimal for needles with small tip radius and large wall thickness. Microneedles inserted into the skin of human subjects were reported as painless. Together, these results suggest that microneedles represent a promising technology to deliver therapeutic compounds into the skin for a range of possible applications.     

Microprocessor controlled transdermal drug delivery

Transdermal drug delivery via iontophoresis is reviewed with special focus on the delivery of lidocaine for local anesthesia and fentanyl for patient controlled acute therapy such as postoperative pain. The role of the microprocessor controller in achieving dosimetry, alternating/reverse polarity, pre-programmed, and sensor-based delivery is highlighted. Unique features such as the use of tactile signaling, telemetry control, and pulsatile waveforms in iontophoretic drug delivery are described briefly.     

Spray-on transdermal drug delivery systems

Introduction: Transdermal drug delivery possesses superior advantages over other routes of administration, particularly minimizing first-pass metabolism. Transdermal drug delivery is challenged by the barrier nature of skin. Numerous technologies have been developed to overcome the relatively low skin permeability, including spray-on transdermal systems.

Areas covered: A transdermal spray-on system (TSS) usually consists of a solution containing the drug, a volatile solvent and in many cases a chemical penetration enhancer. TSS promotes drug delivery via the complex interplay between solvent evaporation and drug–solvent drag into skin. The volatile solvent carries the drug into the upper layers of the stratum corneum, and as the volatile solvent evaporates, an increase in the thermodynamic activity of the drug occurs resulting in an increased drug loading in skin.

Expert opinion: TSS is easily applied, delivering flexible drug dosage and associated with lower incidence of skin irritation. TSS provides a fast-drying product where the volatile solvent enables uniform drug distribution with minimal vehicle deposition on skin. TSS ensures precise dose administration that is aesthetically appealing and eliminates concerns of residual drug associated with transdermal patches. Furthermore, it provides a better alternative to traditional transdermal products due to ease of product development and manufacturing.     

Transfersomes for transdermal drug delivery

Transfersomes^® (Idea AG) are a form of elastic or deformable vesicle, which were first introduced in the early 1990s. Elasticity is generated by incorporation of an edge activator in the lipid bilayer structure. The original composition of these vesicles was soya phosphatidyl choline incorporating sodium cholate and a small concentration of ethanol. Transfersomes are applied in a non-occluded method to the skin and have been shown to permeate through the stratum corneum lipid lamellar regions as a result of the hydration or osmotic force in the skin. They have been used as drug carriers for a range of small molecules, peptides, proteins and vaccines, both in vitro and in vivo. It has been claimed by Idea AG that intact Transfersomes penetrate through the stratum corneum and the underlying viable skin into the blood circulation. However, this has not been substantiated by other research groups who have extensively probed the mechanism of penetration and interaction of elastic vesicles in the skin. Structural changes in the stratum corneum have been identified, and intact elastic vesicles visualised within the stratum corneum lipid lamellar regions, but no intact vesicles have been ascertained in the viable tissues. Using the principle of incorporating an edge-activator agent into a bilayer structure, a number of other elastic vesicle compositions have been evaluated. This review describes the research into the development and evaluation of Transfersomes and elastic vesicles as topical and transdermal delivery systems.     

经皮给药的研究进展

药物的透皮给药主要受到皮肤障碍、药物的分子量和亲水/油性等因素的影响.利用物理和化学方法,同时,辅以载体方法可有效提高药物(尤其是生物大分子药物和复方中药)经皮给药效率.随着透皮给药的不断发展改进,经皮给药系统一定会发挥更大的潜力.     

经皮给药系统促渗方法研究的新进展

促渗方法的发展对于经皮给药的研究意义重大。笔者从化学促渗技术，包括化学促渗剂、前体药物、传递体、含醇脂质体、非离子表面活性剂脂质体和微乳；以及物理促渗技术，包括离子导入、电致孔、超声波促渗、微针、照相波、热致孔和磁场导入等诸多方面综述了近年来经皮给药促渗方法研究的新进展。     

微乳在经皮给药系统中的应用

微乳经皮给药是目前国内外药学工作者研究的重点,也是目前药物制剂研发热点之一。本文主要从微乳的组成、促渗机制、微乳在经皮给药中的应用3个方面进行了综述。微乳经皮给药具有很好的应用前景。