The state-of-the-art of atmospheric pressure plasma for transdermal drug delivery

Plasma-enhanced transdermal drug delivery(TDD) presents advantages over traditional methods,including painless application, minimal skin damage, and rapid recovery of permeability. To harness its clinical potential, factors related to plasma’s unique properties, such as reactive species and electric fields, must be carefully considered.This review provides a concise summary of conventional TDD methods and subsequently offers a comprehensive examination of the current state-of-the-art in plasma-enhanced TDD. This includes an analysis of the impact of plasma on HaCaT human keratinocyte cells, ex vivo/in vivo studies, and clinical research on plasma-assisted TDD. Moreover, the review explores the effects of plasma on skin physical characteristics such as microhole formation, transepidermal water loss(TEWL), molecular structure of the stratum corneum(SC), and skin resistance. Additionally, it discusses the involvement of various reactive agents in plasma-enhanced TDD, encompassing electric fields,charged particles, UV/VUV radiation, heat, and reactive species. Lastly, the review briefly addresses the temporal behavior of the skin after plasma treatment, safety considerations, and potential risks associated with plasma-enhanced TDD.

Ionic liquids as the effective technology for enhancing transdermal drug delivery: Design principles, roles, mechanisms, and future challenges

Ionic liquids (ILs) have been proven to be an effective technology for enhancing drug transdermal absorption. However, due to the unique structural components of ILs, the design of efficient ILs and elucidation of action mechanisms remain to be explored. In this review, basic design principles of ideal ILs for transdermal drug delivery system (TDDS) are discussed considering melting point, skin permeability, and toxicity, which depend on the molar ratios, types, functional groups of ions and inter-ionic interactions. Secondly, the contributions of ILs to the development of TDDS through different roles are described: as novel skin penetration enhancers for enhancing transdermal absorption of drugs;as novel solvents for improving the solubility of drugs in carriers;as novel active pharmaceutical ingredients (API-ILs) for regulating skin permeability, solubility, release, and pharmacokinetic behaviors of drugs;and as novel polymers for the development of smart medical materials. Moreover, diverse action mechanisms, mainly including the interactions among ILs, drugs, polymers, and skin components, are summarized. Finally, future challenges related to ILs are discussed, including underlying quantitative structure-activity relationships, complex interaction forces between anions, drugs, polymers and skin microenvironment, long-term stability, and in vivo safety issues. In summary, this article will promote the development of TDDS based on ILs.

Ginger oil-loaded transdermal adhesive patch treats post-traumatic stress disorder

Objective:To find a viable alternative to reduce the number of doses required for the patients with post-traumatic stress disorder(PTSD),and to improve efficacy and patient compliance.Methods: In this study,we used ginger oil,a phytochemical with potential therapeutic properties,to prepare ginger oil patches.High-performance liquid chromatography(HPLC)was used to quantify the main active component of ginger oil,6-gingerol.Transdermal absorption experiments were conducted to optimize the various pressure-sensitive adhesives and permeation enhancers,including their type and concentration.Subsequently,the ginger oil patches were optimized and subjected to content determination and property evaluations.A PTSD mouse model was established using the foot-shock method.The therapeutic effect of ginger oil patches on PTSD was assessed through pathological sections,behavioral tests,and the evaluation of biomarkers such as tumor necrosis factor-α(TNF-α),interleukin-6(IL-6),brain-derived neurotrophic factor(BDNF),and melatonin(MT).Results: The results demonstrated that ginger oil patches exerted therapeutic effects against PTSD by inhibiting inflammatory responses and modulating MT and BDNF levels.Pharmacokinetic experiments revealed that ginger oil patches maintained a stable blood drug concentration for at least one day,addressing the rapid metabolism drawback of 6-gingerol and enhancing its therapeutic efficacy.Conclusions: Ginger oil can be prepared as a transdermal drug patch that meets these requirements,and the bioavailability of the prepared patch is better than that of oral administration.It can improve PTSD with good patient compliance and ease of administration.Therefore,it is a promising therapeutic formulation for the treatment of PTSD.

Exploring the limited use of transdermal medications in psychiatry:Challenges and potential solutions

Transdermal medications are an useful yet underutilized tool in the field of psychiatry.Despite numerous advantages of using this route of medication delivery,transdermal medications remain less popular compared to other routes of medication administration such as oral and intramuscular routes in the management of various psychiatric conditions.In this editorial,we examine the advantages of transdermal medications with a brief overview of transdermal being used in psychiatry and other medical specialties.We discuss the factors that play a role in their limited usage in psychiatry.We highlight certain patient categories who can specifically benefit from them and discuss potential solutions that can broaden the perspective of treating clinicians making this an intriguing avenue in the field of psychiatry.

Advances in Transdermal Drug Delivery for Cancer Therapy

Transdermal drug delivery offers a promising alternative to traditional cancer therapies by providing a non-invasive,controlled,and targeted delivery of therapeutic agents.This paper explores the advancements,benefits,and challenges associated with transdermal drug delivery systems(TDDS)in cancer treatment.It highlights the mechanisms of action,key technologies,and the potential impact on patient outcomes.By examining recent studies and clinical trials,this paper aims to provide a comprehensive overview of the efficacy,safety,and prospects of transdermal drug delivery in oncology.

Nano transdermal system combining mitochondria-targeting cerium oxide nanoparticles with all-trans retinoic acid for psoriasis

Psoriasis is an inflammatory skin disease that is intricately linked to oxidative stress.Antioxidation and inhibition of abnormal proliferation of keratinocytes are pivotal strategies for psoriasis.Delivering drugs with these effects to the site of skin lesions is a challenge that needs to be solved.Herein,we reported a nanotransdermal delivery system composed of all-trans retinoic acid(TRA),triphenylphosphine(TPP)-modified cerium oxide(CeO2)nanoparticles,flexible nanoliposomes and gels(TCeO_(2)-TRA-FNL-Gel).The results revealed that TCeO_(2)synthesized by the anti-micelle method,with a size of approximately 5 nm,possessed excellent mitochondrial targeting ability and valence conversion capability related to scavenging reactive oxygen species(ROS).TCeO_(2)-TRA-FNL prepared by the film dispersion method,with a size of approximately 70 nm,showed high drug encapsulation efficiency(>96%).TCeO_(2)-TRA-FNL-Gel further showed sustained drug release behaviors,great transdermal permeation ability,and greater skin retention than the free TRA.The results of in vitro EGF-induced and H2O2-induced models suggested that TCeO_(2)-TRA-FNL effectively reduced the level of inflammation and alleviated oxidative stress in HaCat cells.The results of in vivo imiquimod(IMQ)-induced model indicated that TCeO_(2)-TRA-FNL-Gel could greatly alleviate the psoriasis symptoms.In summary,the transdermal drug delivery system designed in this study has shown excellent therapeutic effects on psoriasis and is prospective for the safe and accurate therapy of psoriasis.

Characteristics and Transdermal Drug Delivery of Triamcinolone-Acetonide-Acetate-Loaded Solid Lipid Nanoparticles Carbomer Gel

Aim To prepare triamcinolone-acetonide-acetate (TAA)-loaded solid lipidnanoparticles (SLN) carbomer gel with tripalmitin glyceride (TPG), and investigate theircharacteristics and transdermal drug delivery. Methods SLN suspension was prepared by high-pressurehomogenization technique, and then mixed with carbomer gel matrix to get SLN gel. The morphology,particle size with polydispersi-ty index (PI) and zeta potential were examined by atomic forcemicroscopy (AFM) and photon correlation spectroscopy (PCS). The entrapment efficiency, stability andin vitro drug release were also studied. The transdermal drug delivery through porcine ear skin wasevaluated using modified Franz diffusion cells. Results The SLN had a spherical shape with theaverage size of (95.5 - 186.2) nm, the zeta potential of (-26.3- -15.7) mV and the entrapmentefficiency of 67.4%-90.3% for different TAA encapsulated compounds. TAA-SLN carbomer gel had goodstability, the release profile in vitro fitted Higuchi equation. In comparison with conventionalhydrogels, TAA-SLN carbomer gel resulted in higher drug permeation amount and drug deposition withinporcine ear skin after 24 h penetration experiment. Conclusion TAA-SLN carbomer gel is preparedwith stable physicochemical properties. The release profile and improved drug permeation into skinmake it be a promising vehicle for transdermal drug delivery.

Transdermal Fentanyl for Management of Cancer Pain in Elderly Patients in China

Objective: Objective: To assess the effect and adverse effects of transdermal fentanyl for elderly patients with cancer pain in China. Methods: A total of 1664 elderly patients (aged 65-90 with mean age of 72.6) with cancer pain enrolled in the multicenter study from 136 institutes in China. Of them, 408 (28.8%) patients were 75 years old or older. All patients received transdermal fentanyl for the management of cancer pain. The patients were asked to record the attacks of pain, quality of life, and any side effects of the treatment. Results: Baseline mean of pain intensity was 7.34. On day 1, 3, 6, 9 15, and 30, the pain mean scores were decreased to 3.82, 2.80, 2.43, 2.11, 1.83, 1.64 (P=0.000). The effective rate was 97.18%. The mean doses of fentanyl was 31.34 g/h (25-150 g/h) initially, and 40.59 g/h and 47.50 g/h (25-200 g/h) at day 15 and day 30. At treatment day 15, the dose of fentanyl was ranger from 25 to 50 g/h in 91.8% of patients, 75 to 100 g/h in 7.5% patients, and 125 to 200 g/h only in 0.8% patients. The fine quality of life was in 25.4% patients before treatment, and was 71.15% and 73.04% at day 15 and day 30 respectively (P=0.0000). The common side effects were constipation (10.70%), nausea (11.96%), dizzy (6.85%), vomiting (3.85%), sedation (2.40%), Respiratory depression (0.12%). 86.2% patients preferred continue treated by transdermal fentanyl. Conclusions: Transdermal fentanyl for the elderly with cancer pain is effective, safe, convenient, and can improve the quality of life. Transdermal fentanyl can be recommended as a first-line drug for the treatment of elderly patients with moderate to severe cancer pain, and the initial doses is recommended as 25 g/h.

A continued study on the bisoprolol and isosorbide dinitrate transdermal patches:cardiovascular protection in spontaneously hypertensive rats

The objective of the present study is to examine cardiovascular protective action of a newly developed transdermal patch by incorporating bisoprolol and isosorbide dinitrate in spontaneously hypertensive rats. As the combination therapy with these two synergistic drugs at low doses through a suitable form of administration could provide optimal therapeutic benefit, we further evaluated the effects of a 42 d period of anti-hypertensive treatment in spontaneously hypertensive rats. Rats were divided into the following five groups： control （blank patch）, bisoprolol fumarate tablets （BP-FT, 20.0 mg/kg, i.g.）, bisoprolol transdermal patch （BP-TP, 20.0 mg/kg）, isosorbide dinitrate transdermal patch （ISDN-TP, 20.0 mg/kg）, and the combination of BP and ISDN in a transdermal patch at low doses （8 and 12 mg/kg, respectively）. The effects of treatment were evaluated via biochemical indicators related to cardiovascular protection, structure and function. The combination therapy had synergistic anti-hypertensive effects and significantly reduced blood pressure with the benefit of controlling blood pressure variability compared to BP-FT and BP-TP. The combined treatment also reduced heart rate as well as BP-FT and BP-TP, while ISDN-TP had no evident effects on blood pressure, heart rate, and cardiovascular protection. Combination therapy was superior to BP-TP and BP-FT at increasing blood atrial natriuretic peptide and nitric oxide, while also reducing cardiac hydroxyproline and endothelin-1 with no difference in blood endothelin-1 and cardiac malondialdehyde levels. Cardiovascular remodeling differed among the groups, with the combination therapy reducing cardiac hypertrophy and the aortic media/lumen ratio. The consequential improvements in relaxation in response to cumulative concentrations of acetylcholine may explain the associated improvement in endothelial function. Combi- nation treatment with a transdermal patch exhibited a synergistic therapeutic effect. Such favorable cardiovascular effects with nitric oxide donors and β-blockade combination through a transdermal patch may provide long-term cardiovascular protection during anti-hypertensive treatment.

Expert consensus of the Chinese Association for the Study of Pain on pain treatment with the transdermal patch

Chronic pain lasting more than 3 mo,or even several years can lead to disability.Treating chronic pain safely and effectively is a critical challenge faced by clinicians.Because administration of analgesics through oral,intravenous or intramuscular routes is not satisfactory,research toward percutaneous delivery has gained interest.The transdermal patch is one such percutaneous delivery system that can deliver drugs through the skin and capillaries at a certain rate to achieve a systemic or local therapeutic effect in the affected area.It has many advantages including ease of administration and hepatic first pass metabolism avoidance as well as controlling drug delivery,which reduces the dose frequency and side effects.If not required,then the patch can be removed from the skin immediately.The scopolamine patch was the first transdermal patch to be approved for the treatment of motion sickness by the Food and Drug Administration in 1979.From then on,the transdermal patch has been widely used to treat many diseases.To date,no guidelines or consensus are available on the use of analgesic drugs through transdermal delivery.The pain branch of the Chinese Medical Association,after meeting and discussing with experts and based on clinical evidence,developed a consensus for promoting and regulating standard use of transdermal patches containing analgesic drugs.

Influence of Electric Field Direction on Enhanced Transdermal Delivery of Caffeine by Electroporation

Aim To study the influence of electric field direction on the in vitro enhanced transdermal delivery of caffeine by eleetroporation. Methods Using side-by-side compartment diffusion cells method and Ag-Ag/AgCl electrodes, the transport of caffeine through human cadaver skin by electroporation （exponentially decaying pulse, pulse voltage = 350 V, pulse frequency = 4 pulses· min^-1, capacity = 22 μF, pulse length = 7 ms, 25 pulses） with different electric field directions was carried out and compared with passive diffusion and iontophoresis （0.25 mA·cm^ - 2, lasted for 4 h）. Results （i） The cumulative quantity and flux of caffeine through human skin were increased significantly by eleetroporation or iontophoresis. （ii） The transport of caffeine by positive iontophoresis （ with electric field from donor to receptor compartment） was significantly greater than that by negative iontophoresis （with electric field from receptor to donor compartment）. （iii） The transport of caffeine by positive eleetroporation （with electric field from donor to receptor compartment） was similar to that by negative eleetroporation （with electric field from receptor to donor compartment）. （iv） The enhancing effect of positive iontophoresis on the transdermal delivery of caffeine was significantly greater than that of electroporation （positive or negative）. Conclusion Electric field direction significantly influences the enhancing effect of iontophoresis on the transdermal delivery of caffeine, but does not influence the enhancing effect of eleetroporation.

Research Progress of Transdermal Patches in Veterinary Drug Preparations

With the development of pharmaceutics and other disciplines theories and advanced technologies, the application of many new drug delivery systems has gradually increased in clinical veterinary. Among the many drug delivery systems, transdermal patch can maintain stable and effective plasma concentration and therapeutic effect in vivo for a long time after skin dressing delivery, which provides a safe and effective drug-delivery way for the therapy and prevention of some chronic diseases and partial analgesia in a simple and convenient way. Veterinary drug transdermal preparations have been developed both at home and abroad, and satisfactory results have been achieved in the experimental application. Based on the study of veterinary transdermal patches at home and abroad, this paper systematically describes the development and characteristics of transdermal patches, the factors affecting skin permeation and the evaluation this type of preparations in veterinary drugs.

Preparation of liposomal fluconazole gel and in vitro transdermal delivery

Aim Liposomal fluconazole gel was prepared and its properties were studied. Methods The fluconazole liposomes were prepared by film dispersion method. Their shapes and sizes were observed by transmission electronic microscope and particle size analyzer, respectively. The skin permeation of liposomal gel was studied on rat skin by permeation cell. Results The entrapment efficiency of flueonazole liposomes was 47.68%. The fluconazole liposomes were oval or round in shape, and their average diameter was 250 ± 8 nm. The accumulative skin permeation of liposomal fluconazole gel （25.27%） was lower than that of non-liposomal fluconazole gel （36.72%）, but fluconazole retained in rat skin of liposomal gel （162 ± 15 μg·cm^-2） was higher than that of nonliposomal gel （48 ± 6μg·cm^-2）. Conclusion Liposomal fluconazole gel can significantly increase the deposited amounts of fluconazole in rat skin and it may be beneficial for topical use.

Transdermal drug delivery systems in diabetes management: A review

Diabetes mellitus is a chronic disease in which there is an insufficient production of insulin by the pancreas, or the insulin produced is unable to be utilized effectively by the body. Diabetes affects more than 415 million people globally and is estimated to strike about 642 million people in 2040. The WHO reported that diabetes will become the seventh biggest cause of mortality in 2030. Insulin injection and oral hypoglycemic agents remain the primary treatments in diabetes management. These often present with poor patient compliance. However, over the last decade, transdermal systems in diabetes management have gained increasing attention and emerged as a potential hope in diabetes management owing to the advantages that they offer as compared to invasive injection and oral dosage forms. This review presents the recent advances and developments in transdermal research to achieve better diabetes management. Different technologies and approaches have been explored and applied to the transdermal systems to optimize diabetes management. Studies have shown that these transdermal systems demonstrate higher bioavailability compared to oral administration due to the avoidance of first-pass hepatic metabolism and a sustained drug release pattern. Besides that, transdermal systems have the advantage of reducing dosing frequency as drugs are released at a predetermined rate and control blood glucose level over a prolonged time, contributing to better patient compliance. In summary, the transdermal system is a field worth exploring due to its significant advantages over oral route in administration of antidiabetic drugs and biosensing of blood glucose level to ensure better clinical outcomes in diabetes management.

Fabrication of gelatin methacryloyl hydrogel microneedles for transdermal delivery of metformin in diabetic rats

Injection therapy for diabetes has poor patient compliance,and the pain occurring at the site of subcutaneous injections causes significant inconvenience to diabetic patients.In this work,to demonstrate the benefits of an alternative drug delivery technique that overcomes these issues,methacrylated gelatin hydrogel-forming microneedles integrated with metformin were developed to adjust blood glucose levels in diabetic rats.Gelatin methacryloyl microneedles(GelMA-MNs)with different degrees of substitution were successfully prepared by a micro-molding method.The resultant GelMA-MNs exhibited excellent mechanical properties and moisture resistance.Metformin,an anti-diabetic drug,was further encapsulated into the GelMA-MNs,and its release rate could be controlled by the three-dimensional cross-linked network of microneedles,thereby exhibiting sustained drug release behaviors in vitro and implying a better therapeutic effect compared with that of subcutaneous injection in diabetic rats.The drug release period could be significantly prolonged by improving the cross-link density of GelMA-MNs.The results of hypoglycemic effect evaluation show that the application of GelMA-MNs for transdermal delivery in diabetic rats has promising benefits for diabetes treatment.

Physicochemical Properties and Evaluation of Microemulsion Systems for Transdermal Delivery of Meloxicam

Microemulsion systems, composed of water, isopropyl myristate （IPM）, polyoxyethylene sorbitan trioleate （Tween 85 ）, and ethanol, were investigated as transdermal drug delivery vehicles for a lipophilic model drug（ meloxicam）. The purpose of this study was to investigate the physicochemieal properties of the tested microemulsion and to find the correlation between the physicoehemical properties and the skin permeation rate of the microemulsion. Pseudo-ternary phase diagram of the investigated system at a constant surfactant/cosurfactant mass ratio （ Km = 1 ： 1 ） was constructed by titration at 20℃, and the five fommlations were selected for further research in the o/w microemulsion domains. The values of electrical conductivity and viscosity showed that the selected systems were bicontinuous or non-spherical o/w microemulsion, and the electrical conductivity and viscosity were increased with increasing the content of water. These results suggest that the optimum formulation of microemulsion, containing 0. 375 meloxicam, 5% isopropyl myristate, 25% Tween 85. 25% ethanol, and water, showed the maximum permeation rate. It had a high electrical conductivity, small droplet size, and proper viscocity.

Investigating the potential of essential oils as penetration enhancer for transdermal losartan delivery: Effectiveness and mechanism of action

The effect of tea tree oil(TTO),cumin oil(CO),rose oil(RO)and aloe vera oil(AVO)on the skin permeation of losartan potassium(LP)was investigated.In vitro skin permeation studies were carried out using rat skin.The mechanism of skin permeation enhancement of LP by essential oils treatment was evaluated by FTIR,DSC,activation energy measurement and histopathological examination.Both concurrent ethanol/enhancer treatment and neat enhancer pretreatment of rat SC with all the oils produced significance increase in the LP flux over the control.The effectiveness of the oils as the penetration enhancers was found to be in the following descending order:AVO>RO>CO>TTO.However,only AVO was the only enhancer to provide target flux required to deliver the therapeutic transdermal dose of LP.FTIR and DSC spectra of the enhancer treated SC indicated that TTO,CO,RO and AVO increased the LP permeation by extraction of SC lipids.The results of thermodynamic studies and histopathological examination of AVO treated SC suggested additional mechanisms for AVO facilitated permeation i.e.transient reduction in barrier resistance of SC and intracellular transport by dekeratinization of corneocytes which may be attributed to the presence of triglycerides as constituents of AVO.It is feasible to deliver therapeutically effective dose of LP via transdermal route using AVO as penetration enhancer.

Multicenter Clinical Study for Evaluation of Efficacy and Safety of Transdermal Fentanyl Matrix Patch in Treatment of Moderate to Severe Cancer Pain in 474 Chinese Cancer Patients

Objective: Although a new matrix formulation fentanyl has been used throughout the world for cancer pain management, few data about its efficacy and clinical outcomes associated with its use in Chinese patients have been obtained. This study aimed to assess the efficacy and safety of the new system in Chinese patients with moderate to severe cancer pain. Methods: A total of 474 patients with moderate to severe cancer pain were enrolled in this study and were treated with the new transdermal fentanyl matrix patch (TDF) up to 2 weeks. All the patients were asked to record pain intensity, side effects, quality of life (QOL), adherence and global satisfaction. The initial dose of fentanyl was 25 ?g/h titrated with opioid or according to National Comprehensive Cancer Network (NCCN) guidelines. Transdermal fentanyl was changed every three days. Results: After 2 weeks. The mean pain intensity of the 459 evaluated patients decreased significantly from 5.63?1.26 to 2.03?1.46 (P<0.0001). The total remission rate was 91.29%, of which moderate remission rate 53.16%, obvious remission rate 25.49% and complete remission rate 12.64%. The rate of adverse events was 33.75%, 18.78% of which were moderate and 3.80% were severe. The most frequent adverse events were constipation and nausea. No fatal events were observed. The quality of life was remarkably improved after the treatment (P<0.0001). Conclusion: The new TDF is effective and safe in treating patients with moderate to severe cancer pain, and can significantly improve the quality of life.

Enhanced transdermal delivery of meloxicam by nanocrystals: Preparation, in vitro and in vivo evaluation

Meloxicam(MLX) is efficient in relieving pain and inflammatory symptoms, which, however, is limited by the poor solubility and gastrointestinal side effects. The objective of this study is to develop a nanocrystal formulation to enhance transdermal delivery of MLX. MLX nanocrystals were successfully prepared by the nanoprecipitation technique based on acidbase neutralization. With poloxamer 407 and Tween 80(80/20, w/w) as mixed stabilizers,MLX nanocrystals with particle size of 175 nm were obtained. The crystalline structure of MLX nanocrystals was confirmed by both differential scanning calorimetry and X-ray powder diffractometry. However, the nanoprecipitation process reduced the crystallinity of MLX.Nanocrystals increased both in vitro and in vivo transdermal permeation of MLX compared with the solution and suspension counterparts. Due to the enhanced apparent solubility and dissolution as well as the facilitated hair follicular penetration, nanocrystals present a high and prolonged plasma MLX concentration. And 2.58-and 4.4-fold increase in AUC0 →2 4 h was achieved by nanocrystals comparing with solution and suspension, respectively. In conclusion, nanocrystal is advantageous for transdermal delivery of MLX.

Transdermal delivery of 4-aminopyridine accelerates motor functional recovery and improves nerve morphology following sciatic nerve crush injury in mice

Oral 4-aminopyridine(4-AP)is clinically used for symptomatic relief in multiple sclerosis and we recently demonstrated that systemic 4-AP had previously unknown clinically-relevant effects after traumatic peripheral nerve injury including the promotion of re-myelination,improvement of nerve conductivity,and acceleration of functional recovery.We hypothesized that,instead of oral or injection administration,transdermal 4-AP(TD-4-AP)could also improve functional recovery after traumatic peripheral nerve injury.Mice with surgical traumatic peripheral nerve injury received TD-4AP or vehicle alone and were examined for skin permeability,pharmacokinetics,functional,electrophysiological,and nerve morphological properties.4-AP showed linear pharmacokinetics and the maximum plasma 4-AP concentrations were proportional to TD-4-AP dose.While a single dose of TD-4-AP administration demonstrated rapid transient improvement in motor function,chronic TD-4-AP treatment significantly improved motor function and nerve conduction and these effects were associated with fewer degenerating axons and thicker myelin sheaths than those from vehicle controls.These findings provide direct evidence for the potential transdermal applicability of 4-AP and demonstrate that 4-AP delivered through the skin can enhance in-vivo functional recovery and nerve conduction while decreasing axonal degeneration.The animal experiments were approved by the University Committee on Animal Research(UCAR)at the University of Rochester(UCAR-2009-019)on March 31,2017.