Wearable patches for transdermal drug delivery

Transdermal drug delivery systems (TDDs) avoid gastrointestinal degradation and hepatic first-pass metabolism, providing good drug bioavailability and patient compliance. One emerging type of TDDs is the wearable patch worn on the skin surface to deliver medication through the skin. They can generally be grouped into passive and active types, depending on the properties of materials, design principles and integrated devices. This review describes the latest advancement in the development of wearable patches, focusing on the integration of stimulus-responsive materials and electronics. This development is deemed to provide a dosage, temporal, and spatial control of therapeutics delivery.

Preparation of tanshinone IIA self-soluble microneedles and its inhibition on proliferation of human skin fibroblasts / 中草药·英文版

OBJECTIVE@#Hypertrophic scars (HS) are a variety of skin tissue fibrosis disease that occurs in human skin, the effective therapeutic method of which is still inaccessible up to now. As a bioactive constituent of a well-known medical plant, Salvia miltiorrhiza (Danshen in Chinese), tanshinone IIA (TSA) is reported to inhibit cell proliferation in HS. Therefore, the aim of this study was to prepare TSA self-soluble microneedles to strengthen its dermal retention and break through the difficulty of significantly thickening epidermal connective tissue and stratum corneum at the HS site. The possible mechanism of action in suppressing HS was studied using human skin fibroblasts (HSF).@*METHODS@#Tanshinone IIA self-dissolving microneedles (TSA-MN) was prepared using a negative mold casting method. The prescription process of microneedle was optimized by Box-Behnken effect surface method. Different media were selected to investigate the ability of transdermal absorption and in vitro release. Furthermore, according to Cell Counting Kit-8 (CCK8) method as well as the Western blot method, the effect of TSA-MN on the biological characteristics of HSF was investigated.@*RESULTS@#With remarkable slow release effect and dermal retention, the release and transdermal properties of TSA-MN in vitro were better than both TSA and ordinary dosage forms. Its effect of HSF confirmed the essential decrease in cell motility during cell proliferation and cell migration in vitro, which plays a significant role in down-regulating the secretion of transforming growth factor-β1 (TGF-β1) in HSF and increasing the expression level of Smad7.@*CONCLUSION@#The prepared TSA self-soluble microneedles is helpful in solving the problem of hypertrophic scars, with a stable dermal retention effect after process optimization.

Study on preparation，characterization and in vitro transdermal properties of Xiongzhi shigao decoction soluble microneedles / 中国药房

OBJECTIVE To prepare Xiongzhi shigao decoction soluble microneedles， characterize it and investigate its transdermal properties in vitro. METHODS Two-step centrifugal method was used to prepare Xiongzhi shigao decoction soluble microneedles. The formability and mechanical property of the microneedles were evaluated from aspects of stroma fluidity， microneedle formability， needle hardness， etc. The appearance， mechanical strength， dissolution performance， skin barrier recovery performance and drug loading of the prepared microneedles were characterized by using active components of the soluble microneedle （chlorogenic acid， ferulic acid， notopterol， imperatorin， ligustilide， isoimperatorin） as indicators. The in vitro transdermal performance was investigated by Franz diffusion cell. RESULTS The soluble microneedle tips of Xiongzhi shigao decoction prepared in this study were conical， evenly distributed and of the same thickness， with good mechanical properties； the tip of the needle could be almost completely dissolved after being penetrated into the skin of rats for 2 hours， and the skin barrier recovery performance was good； the drug loading of chlorogenic acid， ferulic acid， notopterol， imperatorin， ligustilide and isoimperatorin were （87.04±1.12）， （67.69±1.23）， （20.65±0.17）， （35.00±0.11）， （153.83±0.21） and （23.52±0.50） μg per patch respectively. The results of in vitro transdermal study showed that cumulative release rates of 6 active components in this microneedle after 72 hours were 36.94%， 56.72%， 19.36%， 57.98%， 11.06% and 35.19%， respectively. CONCLUSIONS Xiongzhi shigao decoction soluble microneedles are prepared successfully in this study and have good formability， mechanical properties and pliable backing， which can significantly promote the transdermal drug delivery.

Analgesic effect of local anesthesia combined with nerve block anesthesia on golden micro-needles for improving facial aging / 中华医学美学美容杂志

Objective:To observe the analgesic effect of local anesthesia combined with nerve block anesthesia on golden microneedles for improving facial aging.Methods:Between December 2018 and December 2019 in Burn and Plastic Surgery of Nanchong Central Hospital, sixty female patients (between 30 and 58 years old, with an average of 45.2 years old) with natural facial skin aging were randomly divided into two groups: Group A: surface anesthesia group (30 cases); Group B: local anesthesia combined with nerve block anesthesia (30 cases). Intraoperative and postoperative pain scores, length of operation, and incidence of adverse reactions were compared between groups A and B.Results:Pain score during surgery was (6.90±0.96) points in Group A, (3.63±0.72) points in Group B. The difference between the two groups was statistically significant ( t=14.93, P<0.05); Pain score at 30 minutes after operation was (2.03±0.62) in Group A, (0.77±0.73) in Group B, the difference between the two groups was statistically significant ( t=7.28, P<0.05). There was no statistically significant difference between the two groups in the pain score at 24 hours after operation ( P>0.05); The operation process in group B was simplified, and the treatment time was significantly shortened. The difference between the two groups was statistically significant ( t=17.93, P<0.05). Conclusions:The method of local anesthesia combined with nerve block anesthesia is used in the treatment of gold microneedles to improve the analgesic effect in facial aging, which significantly shortens the treatment time and has fewer adverse reactions. This method is worth popularizing.

Recent advances in microneedles-mediated transdermal delivery of protein and peptide drugs

Proteins and peptides have become a significant therapeutic modality for various diseases because of their high potency and specificity. However, the inherent properties of these drugs, such as large molecular weight, poor stability, and conformational flexibility, make them difficult to be formulated and delivered. Injection is the primary route for clinical administration of protein and peptide drugs, which usually leads to poor patient's compliance. As a portable, minimally invasive device, microneedles (MNs) can overcome the skin barrier and generate reversible microchannels for effective macromolecule permeation. In this review, we highlighted the recent advances in MNs-mediated transdermal delivery of protein and peptide drugs. Emphasis was given to the latest development in representative MNs design and fabrication. We also summarize the current application status of MNs-mediated transdermal protein and peptide delivery, especially in the field of infectious disease, diabetes, cancer, and other disease therapy. Finally, the current status of clinical translation and a perspective on future development are also provided.

Effects of metal or dissolving microneedles and its parameters of operation on the formation and closure of skin microchannels / 药学学报

To investigate the influence factors and effects of metal or dissolving microneedles on the formation and healing of skin microchannels, the pencil-shaped or conical stainless steel microneedles with different lengths, tip to tip space and base area, and the pencil-shaped dissolving microneedles with different tip to tip space were used. The microneedles were applied to the skin of epilatory mice and rats, and the effects of various microneedle parameters, application parameters, and animals on the microchannels were explored by the transepidermal water loss (TEWL) and methylene blue staining. Visually observe the skin local irritation caused by the microneedles. The animal experiments were approved by the Animal Experiments Welfare and Ethical Committee of Zhejiang University of Technology. The application time of the microneedle should be maintained at 30 s or more. When the insertion forces were 2, 4, 8 N, and the TEWL initial values of the formed microchannels were 12.9, 33.0, 40.4 g·m-2·h-1, respectively. When the length of metal microneedle were 400, 600, 800 μm, and the TEWL initial values of the formed microchannels were 37.1, 40.4, 49.5 g·m-2·h-1, respectively. When the tip to tip space of metal microneedle were 400, 600, 800 μm, and the TEWL initial values of the formed microchannels were 33.2, 40.4, 55.8 g·m-2·h-1, respectively. When the base area of metal microneedle were 0.16, 0.35, 0.62 cm2, and the TEWL initial values of the formed microchannels were 35.1, 40.4, 67.1 g·m-2·h-1, respectively. The effects of conical and pencil-shaped microneedles are similar. When the tip to tip space of pencil shaped dissolving microneedle were 400, 600, 800 μm, and the TEWL initial values of the formed microchannels were 49.8, 60.5, 70.5 g·m-2·h-1, respectively. The TEWL baseline values of animal skins of different genders and series are different, but the tendency of microchannels formation and closure is similar. Visual inspection revealed that the slight erythema caused by the microneedles subsided within 24 h. Microneedles of different parameters have different effects on microchannels. The microchannels closed within 24 or 48 h, and the skin local irritation caused by microneedle was mild.

TPGS/hyaluronic acid dual-functionalized PLGA nanoparticles delivered through dissolving microneedles for markedly improved chemo-photothermal combined therapy of superficial tumor

Nanoparticles (NPs) have shown potential in cancer therapy, while a single administration conferring a satisfactory outcome is still unavailable. To address this issue, the dissolving microneedles (DMNs) were developed to locally deliver functionalized NPs with combined chemotherapy and photothermal therapy (PTT).

Preparation of triptolide-loaded dissolving microneedles and its transdermal penetration / 中国中药杂志

Triptolide(TP), the main active and toxic component of Tripterygium wilfordii, has the limitations of low bioavailability, poor absorption, low concentration in plasma, and small lethal dose. Microneedle(MN), the hybrid of hypodermic needle and transdermal patch, is a physical penetration-enhancing system. Dissolving microneedles(DMNs) can be tailored to specific needs of degradation rate. In this study, the TP-loaded DMNs(DMNs-TP) were prepared with the two-step centrifugation method. The optimal ratio of PVA to PVP K30, water content in matrix solution, demoulding method, and plasticizer for preparing DMNs were investigated with the indexes of formability and mechanical strength. The drug loading capacity was determined by HPLC and morphological characteristics were observed under an optical microscope. The mechanical properties were investigated by H&E staining and Franz diffusion cell was used to detect the in vitro skin permeation characteristics. Through the experiment, we confirmed that the optimal backing material should be PVA and PVP K30(3∶1) and the optimal ratio of matrix material to water should be 3∶4. The prepared DMNs-TP were pyramidal with smooth surface and length of approximately 550 μm. Each patch(2.75 cm~2) had the drug loading capacity of(153.41±2.29) μg, and TP was located in the upper part of the needle. The results of in vitro skin permeation assay demonstrated that the cumulative penetration of TP in DMNs-TP reached 80% in 24 h, while little TP solution penetrated the skin, which proved that DMNs promoted the transdermal delivery of TP.

Preparation of neurotoxin loaded dissolving microneedles and its transdermal penetration / 中草药

Objective: To prepare Naja atra neurotoxin (NT) loaded dissolving microneedles (DMNs-NT), and investigate the physicochemical properties and in vitro transdermal properties. Methods: DMNs-NT was prepared by a two-step centrifugation method. The ratio of CS and PVP K30, the water content of the matrix solution, and the backing layer material were optimized by the indexes of formability and mechanical strength of the microneedles and flexibility of the backing layer. The drug loading content was determined by HPLC, and the morphological characteristics were observed under an optical microscope, and the stability was also examined. Franz diffusion cell was used to investigate its in vitro skin permeation characteristics. Results: Through the single-factor exploration, we confirmed that the optimal prescription technique for DMNs-NT preparation was a 1:1 ratio of CS and PVP k30, a 5:4 ratio of matrix material and water, with CMC as the backing layer material. The DMNs-NT had a pyramidal shape with a smooth surface and a length of approximately 500 μm. The drug loading content of per tablet was (15.4 ± 0.5) μg. The drug was located in the upper part of the needle. DMNs-NT had good stability within 3 months. The results of in vitro skin permeation assay showed that the cumulative penetration of NT in DMNs-NT could reach 95.8% in 4 h, while NT solution barely penetrated the skin, which proved that it had a good promoting effect on NT transdermal delivery. Conclusion: In this study, DMNs-NT had good mechanical properties and good skin penetration, which realized the transdermal drug delivery of macromolecular drugs.

Optimization of Preparation Process of Fast-Dissolving Microneedles by Box-Behnken Method / 中国药学杂志

OBJECTIVE: To optimize the formulation and preparation process of fast-dissolving PVP microneedles, and provide a high-quality carrier for PVP drug-loaded microneedle research. METHODS: On the basis of single factor, the needle tips dissolution time and insertion ratio were used as the evaluation indexes, and the optimal preparation process of microneedle was optimized by Box-Behnken method. RESULTS: From the single factor test and the Box-Behnken test, it was known that the optimum preparation conditions were as follows: the needle tip concentration was 0.70 g•mL-1, the temperature was 40 ℃, and the humidity was 40%. The microneedle height was 600 μm, the width was 200 μm, the pitch was 500 μm, quadrangular pyramid. The area of the microneedle patch was 0.56 cm2, the dissolution time in water was (41.00±3.74)s, and the insertion ratio was (93.19±5.25)%. CONCLUSION: The PVP fast-dissolving microneedles can be prepared simply and conveniently by the Box-Behnken method, which provides a reference for the preparation of further drug-loaded microneedles.

Physical methods for topical skin drug delivery: concepts and applications

Topical drug delivery is an interesting approach to treat skin diseases and to avoid pain and low patient compliance in cases where a systemic delivery is required. However, the stratum corneum, which is the outermost skin layer, strongly protects the body from the entrance of substances, especially those hydrophilic. In this context, different physical methods have been studied to overcome the stratum corneum barrier and facilitate penetration of drugs into or through the skin. Among them, iontophoresis, low-frequency ultrasound and microneedles have been widely employed for transdermal drug delivery. More recently, they are also studied to aid in the treatment of dermatological disorders, such as skin tumors and inflammation. Basically, iontophoresis refers to the movement of charged and non-charged hydrophilic molecules through the skin due to the application of a low constant electric current and the contributions of electromigration and electroosmosis. In low-frequency ultrasound, cavitation is the main mechanism for skin permeabilization that consists on the formation of microbubbles that disorganize the stratum corneum. Microneedles are microprojections, minimally invasive, that can be designed with different lengths, materials and geometry to increase skin permeability. In this review, concepts, mechanisms and applications of these three physical methods will be presented and discussed with focus on their use in dermatological treatments. Moreover, comparative studies using different physical methods will be presented and also some clinical perspectives will be addressed

Synergistic immunoreaction of acupuncture-like dissolving microneedles containing thymopentin at acupoints in immune-suppressed rats

Dissolving microneedles carried drug molecules can effectively penetrate the stratum corneum of skin to improve the transdermal drug delivery. The traditional Chinese medicine acupuncture is based on the needle stimulation at a specific location (acupoint) to generate and transmit biochemical and physiological signals which alter the pathophysiological state of patients. However, the pain associated with conventional acupuncture needles and the requirement of highly trained professionals limit the development of acupuncture in non-Asian countries. The purpose of this study is to investigate whether the dissolving microneedles can be utilized as a self-administered painless replacement for acupuncture and locally released drug molecules can achieve expected therapeutic outcomes. Immunosuppressive rats were treated with acupuncture at Zusanli (ST36) acupoint using microneedles containing thymopentin. The immune functions and psychological mood of the immunosuppressed animals were examined. The proliferation of splenocytes was examined by CCK-8 assay. CD4 and CD8 expression patterns in spleen cells were detected by flow cytometry. The current study showed that use of either microneedles containing thymopentin or conventional acupuncture both resulted in immune cell proliferation, which was confirmed by flow cytometry. Furthermore, either conventional acupuncture or microneedles were able to effectively mitigate the anxiety caused by immune-suppression when applied on the ST36.

Microneedles: quick and easy delivery methods of vaccines

Vaccination is the most efficient method for infectious disease prevention. Parenteral injections such as intramuscular, intradermal, and subcutaneous injections have several advantages in vaccine delivery, but there are many drawbacks. Thus, the development of a new vaccine delivery system has long been required. Recently, microneedles have been attracting attention as new vaccination tools. Microneedle is a highly effective transdermal vaccine delivery method due to its mechanism of action, painlessness, and ease of use. Here, we summarized the characteristics of microneedles and the possibilities as a new vaccine delivery route.

Enhancement of skin permeation of vitamin C using vibrating microneedles

This study was performed to evaluate the use of vibrating microneedles for the transdermal delivery of vitamin C. The microneedles were designed to vibrate at three levels of intensity. In vitro permeation by vitamin C was evaluated according to the specific conditions such as vibration intensity (levels 1, 2 and 3), application time (1, 3, 5, 7 and 10 min), and application power (500, 700 and 1,000 g). The highest permeation of vitamin C was observed at level 3 of vibration intensity, 5 min of application, and 1,000 g of application power. Vitamin C gel showed no cytotoxic effect against Pam212 cells or skin irritation effects. A pharmacokinetic study of the gel in rats was conducted under optimized conditions. The AUC₀-∞ and C(max) increased 1.35-fold and 1.44-fold, respectively, compared with those after vitamin C gel without application with vibrating microneedles. The present study suggests that vibrating microneedles can be used to facilitate the skin permeability of vitamin C under optimal conditions.

Study on the Percutaneous Properties of Man-PEI25k Nanocomplex under the Treatment of Microneedles / 中国药房

OBJECTIVE:To study the percutaneous properties of Man-PEI25k nanocomplex under the treatment of microneedles. METHODS:Using fluorescent dye water-soluble carboxyl CdSe/ZnS quantum dot (QD) as model drug, Man-PEI25k/QD and Man-PEI25k/QD nanocomplex with different grafting rates(1∶3,1∶6)were formed through electrostatic adherence with PEI25k and Man-PEI25k. The distribution of QD in the active epidermal layer and dermis of skin were observed by confocal microscopy after the treatment of microneedles,using free QD as control. The accumulative retention amounts of QD in the active epidermal layer and dermis of skin were determined by fluorescence spectrophotometer after PEI25k/QD and Man-PEI25k/QD nanocomplex treated with mi-croneedles. RESULTS:The amounts of Man-PEI25k/QD nanocomplex in active epidermal layer and dermis were significantly higher than that of PEI25k/QD nanocomplex under the treatment of microneedles in vivo;the amounts of Man-PEI25k/QD (1∶6) nanocom-plex in active epidermal layer and dermis of skin were significantly higher than that of Man-PEI25k/QD(1∶3)nanocomplex. In in vi-tro transdermal diffusion experiments,microneedles could increase the retention amounts of nanocomplex in active epidermal layer and dermis of skin significantly. The retention amounts of Man-PEI25k/QD nanocomplex in active epidermal layer were increased by 2 times of that of PEI25k/QD under the treatment of microneedles after 48 h;at the same time,in the dermis that was increased by 1.5 times,with statistical significance (P<0.01). CONCLUSIONS:Microneedles can improve the percutaneous properties of Man-PEI25k nanocomplex in active epidermal layer.

Pharmacokinetic and pharmacodynamic study of triptolide-loaded liposome hydrogel patch under microneedles on rats with collagen-induced arthritis

Triptolide (TP), a major active component of Tripterygium wilfordii Hook.F. (TWHF), is used to treat rheumatoid arthritis (RA). However, it has a narrow therapeutic window due to its serious toxicities. To increase the therapeutic index, a new triptolide-loaded transdermal delivery system, named triptolide-loaded liposome hydrogel patch (TP-LHP), has been developed. In this paper, we used a micro-needle array to deliver TP-LHP to promote transdermal absorption and evaluated this treatment on the pharmacokinetics and pharmacodynamics of TP-LHP in a rat model of collagen-induced arthritis (CIA). The pharmacokinetic results showed that transdermal delivery of microneedle TP-LHP yielded plasma drug levels which fit a one-compartment open model. The relationship equation between plasma concentration and time was C=303.59×(e(-0.064t) -e(-0.287t) ). The results of pharmacodynamic study demonstrated that TP-LHP treatment mitigated the degree of joint swelling and suppressed the expressions of fetal liver kinase-1, fetal liver tyrosine kinase-4 and hypoxia-inducible factor-1α in synovium. Other indicators were also reduced by TP-LHP, including hyperfunction of immune, interleukin-1β and interleukin-6 levels in serum. The therapeutic mechanism of TP-LHP might be regulation of the balance between Th1 and Th2, as well as inhibition of the expression and biological effects of vascular endothelial growth factor.

Microneedle patches for vaccine delivery

In today's medical industry, the range of vaccines that exist for administration in humans represents an eclectic variety of forms and immunologic mechanisms. Namely, these are the live attenuated viruses, inactivated viruses, subunit proteins, and virus-like particles for treating virus-caused diseases, as well as the bacterial-based polysaccharide, protein, and conjugated vaccines. Currently, a new approach to vaccination is being investigated with the concept of DNA vaccines. As an alternative delivery route to enhance the vaccination efficacy, microneedles have been devised to target the rich network of immunologic antigen-presenting cells in the dermis and epidermis layers under the skin. Numerous studies have outlined the parameters of microneedle delivery of a wide range of vaccines, revealing comparable or higher immunogenicity to conventional intramuscular routes, overall level of stability, and dose-sparing advantages. Furthermore, recent mechanism studies have begun to successfully elucidate the biological mechanisms behind microneedle vaccination. This paper describes the current status of microneedle vaccine research.

Microagujas y Transcutol® como promotores de la penetración transdérmica de sibutramina formulada en parche transdérmico / Microneedles and Transcutol® as transdermal penetration enhancers of sibutramine formulated in a transdermal patch

Introducción: la principal barrera de permeación que tenemos es la piel. A pesar de ser una barrera casi impermeable para la mayoría de sustancias, se han buscado maneras para mejorar su permeabilidad utilizando nuevas tecnologías como es el uso de microagujas o promotores químicos como el Transcutol®. Objetivo: desarrollar y caracterizar un parche transdérmico a base de clorhidrato de sibutramina como fármaco modelo, usando Transcutol® y microagujas como agentes promotores de la penetración transdérmica. Métodos: se realizó la caracterización fisicoquímica de los parches mediante estudios de microscopia con luz polarizada, estudios de bioadhesión y resistencia a la ruptura. Los estudios de difusión se efectuaron en celdas de difusión verticales tipo Franz, utilizando piel abdominal humana como membrana entre ambos compartimentos. La cuantificación del principio activo se realizó mediante electroforesis capilar. Resultados: se obtuvieron parches bioadhesivos, con una adecuada estabilidad del activo en la matriz polimérica de quitosán al no precipitarse. El uso de Transcutol® y microagujas incrementó el paso de clorhidrato de sibutramina a través de piel humana con respecto al parche control. Se obtuvieron valores de flujo de 0,0649 mg.cm-2.h-1 y 0,0816 mg.cm-2.h-1 en el parche con agente promotor y microagujas de 1 y 2 mm respectivamente, en comparación con los valores de flujo de 0,0527 mg.cm-2.h-1 y 0,0554 mg.cm-2.h-1 para el parche sin agente promotor (control) utilizando microagujas de 1 y 2 mm respectivamente. Conclusiones: los resultados ponen de manifiesto la posibilidad de usar Transcutol® y microagujas para incrementar el paso de fármacos potentes y con estructura similar a la sibutramina por vía transdérmica, lo que genera de esta manera nuevas alternativas a las formas farmacéuticas orales para el tratamiento de padecimientos y enfermedades(AU)

Introduction: the main permeation barrier is the skin. Although it is almost an impermeable barrier to most substances, new ways have been examined to improve its permeability by using new technologies such as microneedles and chemical enhancers like Transcutol®. Objective: to develop and to characterize a transdermal patch containing sibutramine hydrochloride as model drug and using microneedles and Transcutol® as transdermal drug delivery enhancers. Methods: Physicochemical characterization of sibutramine hydrochloride patches using polarized light microscopy, bioadhesion, tensile strength studies. The diffusion studies were performed in Franz-type diffusion cells with human abdominal skin as a sort of membrane between both compartments. The active ingredient was quantified through capillary electrophoresis. Results: bioadhesive patches were obtained, with adequate stability of sibutramine hydrochloride in the polymer matrix of chitosan. The use of microneedles and Transcutol® increased sibutramine hydrochloride delivery through the human skin when compared with the control patch. The flow rates were 0.0649 mg.cm-2.h-1 and 0,0816 mg.cm-2.h-1 in the enhanced patch by using 1 and 2 mm microneedles respectively, in comparison with flow rates of 0,0527 mg.cm-2.h-1 and 0.0554 mg.cm-2.h-1 for the control patch having no enhancing agent with 1 and 2 mm microneedles respectively. Conclusions: the results show that it is possible to use Transcutol® and microneedles to increase the delivery of potent drugs having a structure similar to that of sibutramine through transdermal administration. All this generates new alternatives to oral pharmaceuticals in order to treat ailments and diseases(AU)

Microneedle technique in promoting transdermal delivery of arbutin / 第二军医大学学报

Objective: To study the promoting effects of microneedle arrays on transdermal delivery of arbutin by comparing with the effect of chemical penetration enhancer azone. Methods: The microneedles were fabricated with single-crystal Si as starting material using a series of photolithography, thin-film deposition, and reactive ion etching techniques. Franz-cells were used in the transdermal delivery experiment with human abdominal skin. The study was divided into the following 3 groups; the microneedle group (arbutin hydrogel without penetration enhancer, and the skin was treated with microneedle arrays) ; the control group (arbutin hydrogels containing 1% , 3% , and 5% azone (W/V) , and the skin received no microneedle treatment); and blank control group (arbutin hydrogel without azone, and the skin received no microneedle treatment). Arbutin levels in the receptor solution, epidermis and dermis were determined by HPLC at 1, 3 , 6 , 12, 24, 36 and 48 h. The analyses were performed with a C18 column (250 mm X 4.6 mm, 5μm), at room temperature, mobile phase methanol : 1×10-3 mol/ml HCl solution (V/V, 5 : 95), flow rate 1 ml/min, and detective wavelength 282 nm. The accumulative penetration amount (Qr), steady-state flux (J s) and the accumulative deposition amount (Qs) were calculated. Results: The microneedles could pass the human skin. The standard curve was; C=0.000 2A=0.182 9 (r=0.999 9) , 0.4-50 μg/ml. The RSD values of intraday and interday precisions were 2.4% and 2.74%, respectively; and the recovery was higher than 90%. The values of Qr, Js, and Qs in the microneedle group were significantly higher than those in the 5% azone group (P<0.01). Conclusion: Microneedles can greatly promote the skin permeability and deposition of arbutin.

Study on microneedle technique in enhancement of transdermal nanoparticle delivery / 第二军医大学学报

Objective: To investigate the microneedle technique in enhancement of transdermal nanoparticle delivery and the distribution of poly (D,L-lactic-co-glycolic acid) (PLGA) nanoparticles in the skin and the transdermal microconduits. Methods: Double fluorescent PLGA nanoparticles were used to show the transdermal transport process. Franz diffusion cell was used for the transdermal study. The nanoparticle suspension was added to the donor chamber. The hairless mouse skin in the microneedle group was treated by microneedle technique and that in the control group was not treated. Penetration of nanoparticles was visualized by confocal laser scanning microscopy (CLSM). Distribution of nanoparticle diameter was quantified by HPLC. Results: The CLSM images revealed that the nanoparticles were delivered into the microconduits created by microneedles and entered the epidermis and the dermis. The quantitative results showed that no nanoparticles reached the receptor compartment 48 h after addition of the nanoparticles in both groups. In microneedle group the nanoparticle amount was 125.99 μg/cm2 in the epidermis and 55.31 μg/cm2 in the dermis, with the total amount in the skin being 181.30 μg/cm2; in the the control group, the nanoparticle amount was 42.15 μg/cm2 in the epidermis and 32.76 μg/cm2 in the dermis, with the total amount in the skin being 74.91 μg/cm2. Microneedle technique significantly increased the amount of nanoparticles entering the skin (P<0.01), and the amount in the epidermis was significantly more than that in the dermis (P<0.01). Conclusion: Our results suggest that microneedles can enhance the intradermal PLGA nanoparticle delivery, and the nanoparticles deposit in the skin to achieve sustainable drug release, which is beneficial for topical drug administration.