Microneedles as the technique of drug delivery enhancement in diverse organs and tissues

Bioinspired Rotation Microneedles for Accurate Transdermal Positioning and Ultraminimal-Invasive Biomarker Detection with Mechanical Robustness

Microneedle permits transdermal biosensing and drug delivery with minor pain. However, accurate microneedle transdermal positioning with minimal skin deformation remains a significant technical challenge due to inhomogeneous skin topology and discontinuous force applied to the microneedle. Here, we introduce bioinspired rotation microneedles for in vivo accurate microneedle positioning as inspired by honeybees’ stingers. We demonstrate the benefits of rotation microneedles in alleviating skin resistance through finite element analysis, full-thickness porcine validations, and mathematical derivations of microneedle-skin interaction stress fields. The max penetration force was mitigated by up to 45.7% and the force attenuation rate increased to 2.73 times in the holding stage after penetration. A decrease in max skin deflection and a faster deformation recovery introduced by rotation microneedles implied a more precise penetration depth. Furthermore, we applied the rotation microneedles in psoriasis mice, a monogenic disorder animal model, for minimally invasive biological sample extraction and proinflammatory cytokine monitoring. An ultrasensitive detection method is realized by using only one microneedle to achieve cytokine mRNA level determination compared to commonly required biopsies or blood collection. Thus, rotation microneedles permit a simple, rapid, and ultraminimal-invasive method for subcutaneous trace biological sample acquisition and subsequent point-of-care diagnostics with minimal damage to both microneedles and skins.

Recent Advances of Microneedles and Their Application in Disease Treatment

For decades, scientists have been doing a lot of research and exploration to find effective long-term analgesic and/or disease-modifying treatments. Microneedles (MNs) are a simple, effective, and painless transdermal drug delivery technology that has emerged in recent years, and exhibits great promise for realizing intelligent drug delivery. With the development of materials science and fabrication technology, the MN transdermal drug delivery technology has been applied and popularized in more and more fields, including chronic illnesses such as arthritis or diabetes, cancer, dermatocosmetology, family planning, and epidemic disease prevention, and has made fruitful achievements. This paper mainly reviews the latest research status of MNs and their fabrication methodology, and summarizes the application of MNs in the treatment of various diseases, as well as the potential to use nanotechnology to develop more intelligent MNs-based drug delivery systems.

Micro/nanofluidic devices for drug delivery

Micro/nanofluidic drug delivery systems have attracted significant attention as they offer unique advantages in targeted and controlled drug delivery. Based on the desired application, these systems can be categorized into three different groups: in vitro, in situ and in vivo microfluidic drug delivery platforms. In vitro microfluidic drug delivery platforms are closely linked with the emerging concept of lab-on-a-chip for cell culture studies. These systems can be used to administer drugs or therapeutic agents, mostly at the cellular or tissue level, to find the therapeutic index and can potentially be used for personalized medicine. In situ and in vivo microfluidic drug delivery platforms are still at the developmental stage and can be used for drug delivery at tissue or organ levels. A famous example of these systems are microneedles that can be used for painless and controllable delivery of drugs or vaccines through human skin. This chapter presents the cutting edge advances in the design and fabrication of in vitro microfluidic drug delivery systems that can be used for both cellular and tissue drug delivery. It also briefly discusses the in situ drug delivery platforms using microneedles.

Intradermal injection of lidocaine with a microneedle device to provide rapid local anaesthesia for peripheral intravenous cannulation: A randomised open-label placebo-controlled clinical trial

Background

Peripheral venous cannulation is one of the most common procedures in medicine. It is associated with noticeable pain and apprehension, although in most cases it is performed without any anesthesia due to lack of a painless, cost-effective option, which would provide rapid local anesthesia with subsequent significant reduction in the experienced pain. We conducted an open-label placebo-controlled clinical trial to evaluate the efficacy and safety of a 2% lidocaine injection using the commercially available microneedle device MinronJet600 (NanoPass Technologies Ltd, Israel) to achieve rapid local anesthesia prior to peripheral venous cannulation.

Methods

One hundred and two subjects were randomly allocated into two groups. In the first group, 100μL of lidocaine hydrochloride (2%) was injected intradermally to subjects using the MicronJet600 device in the left arm (MJ-Lido) and 100μL of saline was injected intradermally using the device in the right arm (MJ-Saline). In the second group, 100μL of lidocaine hydrochloride (2%) was injected using the MicronJet600 device into the left arm (MJ-Lido), with no injection into the right arm of subjects (No pretreatment). In both groups the intradermal injection was performed at the cannulation site prior to insertion of a 18G cannula into a median cubital vein in both arms. As a primary variable, a score of cannulation-induced pain was indicated by subjects using a 100-point visual analog scale immediately after cannulation. As a secondary variable, subjects in Group 2 also indicated their preference to receive the anaesthetic injection with MicronJet600 in the future by using the 5-point Likert scale. Also, as a secondary variable, the duration of skin numbness after lidocaine injection was indicated by performing a superficial pin-prick with a 27G needle at 15, 30 and 45 minutes, at distances of 1, 2 and 3 centimeters from the injection site.

Results

A significant pain reduction (11.0-fold) was achieved due to the lidocaine injection compared to the cannulation without any pretreatment (p< 0.005). After the lidocaine injection the anesthesia was effective up to 2 centimeters from the injection site and remained for up to 30 minutes. Eighty percent of subjects from the second group preferred cannulation after the lidocaine injection over cannulation without any pretreatment. No significant side effects were identified.

Conclusion

Intradermal injection of anaesthetic with Micronjet600 was found to be a safe and effective option for providing rapid local anesthesia for peripheral intravenous cannulation.

Trial regiatration

The clinical trial was registered, before the patient enrollment began, in the Research Registry publicly accessible database (registration identifier: researchregistry4662). Also, the trial was registered in ClinicalTrials.gov (registration identifier: NCT05108714) after its completion.

Besifloxacin-loaded ocular nanoemulsions: design, formulation and efficacy evaluation

The purpose of this study was to develop and evaluate nanoemulsions (NEs) containing besifloxacin for ocular drug delivery. Pseudo ternary phase diagrams were constructed using Triacetin (oil), Cremophor® RH 40 (surfactant), and Transcutol®P (co-surfactant) to identify NE regions. Six formulations were developed by low-energy emulsification method and then evaluated for size, refractive index, pH, osmolality, viscosity, and drug release. After accelerated physical stability and bovine conrneal permeation studies, NE2 was chosen as optimized formulation forantimicrobial efficacy, and hen's egg test-chorioallantoic membrane (HET-CAM) tests. The particle size of optimum NE was 14 nm with a narrow size distribution. Moreover, other physicochemical characterizations were in the acceptable range for ocular administration. Besifloxacin-loaded NEs demonstrated sustained release pattern and 1.7-fold higher permeation compared with the control suspension in the ex vivo transcorneal permeation study. HET-CAM test indicated no irritation, and HL% revealed no damage to the tissue, so the optimum NE is well tolerated by the eye. In vitro antimicrobial evaluation, showed comparative efficacy of lower drug-loaded NE (0.2%) versus 0.6% besifloxacin suspension (equal concentration to commercial besifloxacin eye drop). In conclusion, besifloxacin-loaded NEs could be considered as a suitable alternative to the marketed suspension for treating bacterial eyeinfections.

Non-dermal applications of microneedle drug delivery systems

Microneedles (MNs) are micron-scaled needles measuring 100 to 1000 μm that were initially explored for delivery of therapeutic agents across the skin. Considering the success in transcutaneous drug delivery, the application of microneedles has been extended to different tissues and organs. The review captures the application of microneedles to the oral mucosa, the eye, vagina, gastric mucosa, nail, scalp, and vascular tissues for delivery of vaccines, biologics, drugs, and diagnostic agents. The technology has created easy access to the poorly accessible segments of eye to facilitate delivery of monoclonal antibodies and therapeutic agents in management of neovascular disease. Microporation has been reported to drastically improve the drug delivery through the poorly permeable nail plate. Curved microneedles and spatially designed microneedle cuffs have been found to be capable of delivering stem cells and therapeutic macromolecules directly to the cardiac tissue and the vascular smooth muscle cells, respectively. Besides being minimally invasive and patient compliant, the technology has the potential to offer viable solutions to deliver drugs through impermeable barriers owing to the ability to penetrate several biological barriers. The technology has been successful to overcome the delivery hurdles and enable direct delivery of drug to the target sites, thus maximizing the efficacy thereby reducing the required dose. This review is an attempt to capture the non-dermatological applications of microneedles being explored and provides an insight on the future trends in the field of microneedle technology. Pictorial representation of different microneedle application.

Silk fibroin double-layer microneedles for the encapsulation and controlled release of triptorelin

A double-layer silk fibroin microneedles (SF-MNs) was proposed for the transdermal delivery of triptorelin. Two-step pouring and centrifugation were employed to prepare SF-MNs. Triptorelin was wrapped in MNs in the form of microcrystals with a size of ∼1 μm. β-sheet nanocrystals (the secondary structure of silk fibroin) were adjusted in content by methanol-vapor treatment to manipulate the characteristics of SF-MNs prepared with two concentrations of silk fibroin. The mechanical strength of MNs was measured and analyzed in proportion to the β-sheet content. The triptorelin in MNs could be released sustainedly in phosphate-buffered saline for 168 h, and the release amount decreased with increasing β-sheet content. The Ritger-Peppas equation was employed to fit the release data. A linear decreasing relationship was observed between the diffusion coefficient and increased β-sheet content. After administration to rats, SF-MNs exhibited long-term testosterone inhibition and maintained castration levels for ≥7 d. Manipulable mechanical properties and release behavior combined with biocompatibility and biodegradability render SF-MNs as viable long-term transdermal delivery devices for triptorelin.

A Facile Low-Dose Photosensitizer-Incorporated Dissolving Microneedles-Based Composite System for Eliciting Antitumor Immunity and the Abscopal Effect

Nanomedicine-based photodynamic therapy (PDT) for melanoma treatment has attracted great attention. However, the complex design of polymer nanoparticles and high doses of photosensitizers used in intravenous injections (for sufficient accumulation of drugs in tumor lesions) pose a huge challenge to the commercialization and further clinical application. Herein, we fabricated the carrier-free nanoassemblies of a chlorin e6 (L-Ce6 NAs)-integrated fast-dissolving microneedles patch (L-Ce6 MNs) enriching only about 3 μg of Ce6 in the needle tips via a facile fabrication method. The L-Ce6 MNs had sufficient mechanical strength to penetrate the skin and facilitated the transportation of L-Ce6 NAs to a depth of 200-500 μm under the skin, thereby achieving efficient and accurate drug delivery to tumor lesions. In a xenograft mouse melanoma model, the L-Ce6 MNs-based PDT with low dose of Ce6 (0.12 mg/kg) exerted efficient ablation of the primary lesions in situ through reactive oxygen species (ROS) generation. More importantly, a significant abscopal effect was also elicited by activating immunogenic cell death (ICD) and releasing danger-associated molecular patterns (DAMPs), which in turn promoted dendritic cells (DCs) maturation and the subsequent antigen presentation, thereby facilitating the T-cell-mediated immune response without synergetic immunotherapies. Collectively, our findings indicate the facile, controllable, and fast-dissolving microneedles patch with a low dose of photosensitizers presented great therapeutic potential for enhanced photoimmunotherapy.

Strategy for osteoarthritis therapy: Improved the delivery of triptolide using liposome-loaded dissolving microneedle arrays

Osteoarthritis (OA) is a chronic disease that seriously impairs people's physical function and quality of life. Triptolide (TP), as a promising anti-inflammatory drug for the treatment of OA, has limited clinical application due to its severe systemic toxicity, poor solubility and rapid elimination in the body. To extend its application prospect for OA treatment. We have developed a liposome-loaded dissolving microneedle (DMN) system, which can effectively deliver poorly water-soluble TP and improve OA symptoms. To incorporate TP into DMNs, triptolide liposome (TP-Lipo) with entrapment efficiency of 90.25% was prepared by ethanol injection. Subsequently, TP-Lipo was concentrated by ultrafiltration tube and mixed with hyaluronic acid solution to prepare DMNs, TP-Lipo-loaded DMNs (TP-Lipo@DMNs) showed sufficient mechanical and insertion properties to penetrate about 200 μm of rat skin. The drug distribution in vivo showed that TP-Lipo@DMNs had a slow-release effect compared with intra-articular injection. In vivo pharmacodynamic research showed that TP-Lipo@DMNs significantly reduced knee joint swelling and the level of inflammatory cytokines (TNF-α, IL-1β, IL-6). Micro-CT and histological evaluation showed that TP-Lipo@DMNs effectively reduced cartilage destruction and alleviated OA symptoms. These results support that TP@Lipo@DMNs may be a promising option for OA treatment.

Dissolving microneedle patches loaded with amphotericin B microparticles for localised and sustained intradermal delivery: Potential for enhanced treatment of cutaneous fungal infections

Fungal infections affect millions of people globally and are often unreceptive to conventional topical or oral preparations because of low drug bioavailability at the infection site, lack of sustained therapeutic effect, and the development of drug resistance. Amphotericin B (AmB) is one of the most potent antifungal agents. It is increasingly important since fungal co-infections associated with COVID-19 are frequently reported. AmB is only administered via injections (IV) and restricted to life-threatening infections due to its nephrotoxicity and administration-related side effects. In this work, we introduce, for the first time, dissolving microneedle patches (DMP) loaded with micronised particles of AmB to achieve localised and long-acting intradermal delivery of AmB for treatment of cutaneous fungal infections. AmB was pulverised with poly (vinyl alcohol) and poly (vinyl pyrrolidone) to form micronised particles-loaded gels, which were then cast into DMP moulds to form the tips. The mean particle size of AmB in AmB DMP tips after pulverisation was 1.67 ± 0.01 μm. This is an easy way to fabricate and load microparticles into DMP, as few steps are required, and no organic solvents are needed. AmB had no covalent chemical interaction with the excipients, but the crystallinity of AmB was reduced in the tips. AmB was completely released from the tips within 4 days in vitro. AmB DMP presented inhibition of Candida albicans (CA) and the killing rate of AmB DMP against CA biofilm inside porcine skin reached 100% within 24 h. AmB DMP were able to pierce excised neonatal porcine skin at an insertion depth of 301.34 ± 46.86 μm. Ex vivo dermatokinetic and drug deposition studies showed that AmB was mainly deposited in the dermis. An in vivo dermatokinetic study revealed that the area under curve (AUC_0-inf) values of AmB DMP and IV (Fungizone® bolus injection 1 mg/kg) groups were 8823.0 d∙μg/g and 33.4 d∙μg/g, respectively (264-fold higher). AmB remained at high levels (219.07 ± 102.81 μg/g or more) in the skin until 7 days after the application of AmB DMP. Pharmacokinetic and biodistribution studies showed that AmB concentration in plasma, kidney, liver, and spleen in the AmB DMP group was significantly lower than that in the IV group. Accordingly, this system addressed the systemic side effects of intravenous injection of AmB and localised the drug inside the skin for a week. This work establishes a novel, easy and effective method for long-acting and localised intradermal drug delivery.

Intelligent and spatiotemporal drug release based on multifunctional nanoparticle-integrated dissolving microneedle system for synergetic chemo-photothermal therapy to eradicate melanoma

Cutaneous melanoma is one of the most common malignant skin cancer with high lethality. Chemotherapy and photothermal therapy are important and extensively studied treatment modalities for melanoma. However, these therapies still face some challenges, which severely restrict their further applications, such as unsatisfactory efficacy of monotherapy, nonspecific uptake and release during drug delivery, and unexpected adverse effects from system administration. Recently, the strategies of collaboration, functional modification, stimuli-responsive design, and topical administration all show great prospect for solving above problems. In this research, a multifunctional nanoparticle-integrated dissolving microneedle drug delivery system was constructed, in which the nanoparticles were prepared based on the framework with the incorporation of photothermal agent (CuS) into Zeolitic imidazolate framework-8 and functionalized by hyaluronic acid. This system can co-load multi-modal drugs, improve specific uptake and distribution of targeted tumor, deliver drug locally, and release drug intelligently and spatiotemporally, thereby promising a low-dose administration with high efficiency. The high inhibiting tumor performance and excellent systematic safety were verified both in vitro and in vivo. Together, this smart design overcame the drawbacks of monotherapy and conventional system administration. We believe the nanoparticle-integrated dissolving microneedles will be in prospect of clinical application for more superficial tumors with further delicate optimization. STATEMENT OF SIGNIFICANCE: Melanoma is one of the most common skin cancers with high lethality. Extensively studied chemotherapy and photothermal therapy still face some challenges, such as the limited therapeutic efficacy and the severe system adverse effects. In order to overcome these drawbacks, the multifunctional nanoparticle-integrated dissolving microneedles (DMNs) were designed. Especially, the nanoparticles could co-load multi-modal drugs, improve specific uptake, and release drug intelligently and spatiotemporally. The microneedles could increase the drug accumulation in tumor, thus achieving excellent therapeutic efficacy and reducing side effects. This system paved the way to a less invasive, more focused and efficient therapeutic strategy for melanoma therapy.

Nitric Oxide Nanomotor Driving Exosomes-Loaded Microneedles for Achilles Tendinopathy Healing

The microneedle (MN) provides a promising strategy for transdermal delivery of exosomes (EXO), in which the therapeutic effects and clinical applications are greatly reduced by the fact that EXO can only partially reach the injury site by passive diffusion. Here, we designed a detachable MN array to deliver EXO modified by a nitric oxide nanomotor (EXO/MBA) for Achilles tendinopathy (AT) healing. With the releasing of EXO/MBA, l-arginine was converted to nitric oxide by NOS or ROS as the driving force. Benefiting from the motion ability and the property of MPC tending to lower pH, EXO could accumulate at the injury site more efficiently. This work demonstrated that EXO/MBA-loaded MN notably suppressed the inflammation of AT, facilitated the proliferation of tendon cells, increased the expression of Col1a, and prevented extracellular matrix degradation, indicating its potential value in enthesiopathy healing and other related biomedical fields.

Chemical imaging analysis of active pharmaceutical ingredient in dissolving microneedle arrays by Raman spectroscopy

The purpose of this study was to develop a quality evaluation method for dissolving microneedle arrays (DMNAs) and determine the spatial distribution pattern of drugs in DMNAs. Raman spectroscopy mapping was used to visualize the drug distribution in DMNAs and drug-loaded polymer films as a model. Powder X-ray diffraction (PXRD) and high-pressure liquid chromatography were also performed to characterize DMNAs. Drug-loaded polymer films and DMNAs were prepared by drying the aqueous solutions spread on the plates or casting. PXRD analysis suggested the crystallization of diclofenac sodium (DCF) in several forms depending on its amount in the sodium hyaluronate (HA)-based films. The Raman spectra of HA and DCF showed characteristic and non-overlapping peaks at 1376 and 1579 cm^-1 Raman shifts, respectively. The intensity of the characteristic peak of DCF in the DCF-loaded films increased linearly with the increasing drug content in the range of 4.8 to 16.7% (DCF, w/w). Raman imaging analysis revealed a homogenous dispersion of small DCF crystals in these films. Raman imaging indicates the distribution of DCF on the surface of the DMNA needle. This work highlights the benefit of using Raman spectroscopy mapping to reveal the spatial distribution of drugs in DMNAs.

A Comprehensive Review of Microneedles: Types, Materials, Processes, Characterizations and Applications

Drug delivery through the skin offers many advantages such as avoidance of hepatic first-pass metabolism, maintenance of steady plasma concentration, safety, and compliance over oral or parenteral pathways. However, the biggest challenge for transdermal delivery is that only a limited number of potent drugs with ideal physicochemical properties can passively diffuse and intercellularly permeate through skin barriers and achieve therapeutic concentration by this route. Significant efforts have been made toward the development of approaches to enhance transdermal permeation of the drugs. Among them, microneedles represent one of the microscale physical enhancement methods that greatly expand the spectrum of drugs for transdermal and intradermal delivery. Microneedles typically measure 0.1-1 mm in length. In this review, microneedle materials, fabrication routes, characterization techniques, and applications for transdermal delivery are discussed. A variety of materials such as silicon, stainless steel, and polymers have been used to fabricate solid, coated, hollow, or dissolvable microneedles. Their implications for transdermal drug delivery have been discussed extensively. However, there remain challenges with sustained delivery, efficacy, cost-effective fabrication, and large-scale manufacturing. This review discusses different modes of characterization and the gaps in manufacturing technologies associated with microneedles. This review also discusses their potential impact on drug delivery, vaccine delivery, disease diagnostic, and cosmetics applications.

Pharmaceutical Perspective in Wearable Drug Delivery Systems

Humans have been dealing with health problems for millions of years. Normal health services need well-trained personnel and high-cost diagnostic tests, which forces patients to go to hospitals if medical treatment is required. To address this, prototype testing has been carried out into the wearable drug delivery health care perspectives. Researchers have devised a wide variety of formulations for the treatment of various diseases at home by performing real-time monitoring of different routes of drug administration such as ocular, transdermal, intraoral, intracochlear, and several more. A comprehensive review of the different types of wearable drug delivery systems with respect to their manufacturing, mechanism of action and specifications has been done. In the pharmaceutical context, these devices are technologically well-equipped interfaces for diverse physicochemical signals. Above mentioned information with a broader perspective has also been discussed in this article. Several wearable drug delivery systems have been introduced in the market in recent years. But a lot of testing needs to be conducted to address the numerous obstacles before the wearable devices are successfully launched in the market.

Oral delivery of proteins and peptides: Challenges, status quo and future perspectives

Proteins and peptides (PPs) have gradually become more attractive therapeutic molecules than small molecular drugs due to their high selectivity and efficacy, but fewer side effects. Owing to the poor stability and limited permeability through gastrointestinal (GI) tract and epithelia, the therapeutic PPs are usually administered by parenteral route. Given the big demand for oral administration in clinical use, a variety of researches focused on developing new technologies to overcome GI barriers of PPs, such as enteric coating, enzyme inhibitors, permeation enhancers, nanoparticles, as well as intestinal microdevices. Some new technologies have been developed under clinical trials and even on the market. This review summarizes the history, the physiological barriers and the overcoming approaches, current clinical and preclinical technologies, and future prospects of oral delivery of PPs.

The role of microneedle arrays in drug delivery and patient monitoring to prevent diabetes induced fibrosis

Diabetes affects approximately 450 million adults globally. If not effectively managed, chronic hyperglycaemia causes tissue damage that can develop into fibrosis. Fibrosis leads to end-organ complications, failure of organ systems occurs, which can ultimately cause death. One strategy to tackle end-organ complications is to maintain normoglycaemia. Conventionally, insulin is administered subcutaneously. Whilst effective, this delivery route shows several limitations, including pain. The transdermal route is a favourable alternative. Microneedle (MN) arrays are minimally invasive and painless devices that can enhance transdermal drug delivery. Convincing evidence is provided on MN-mediated insulin delivery. MN arrays can also be used as a diagnostic tool and monitor glucose levels. Furthermore, sophisticated MN array-based systems that integrate glucose monitoring and drug delivery into a single device have been designed. Therefore, MN technology has potential to revolutionise diabetes management. This review describes the current applications of MN technology for diabetes management and how these could prevent diabetes induced fibrosis.

Polymeric microneedle‐mediated sustained release systems: Design strategies and promising applications for drug delivery

Parenteral sustained release drug formulations, acting as preferable platforms for long-term exposure therapy, have been wildly used in clinical practice. However, most of these delivery systems must be given by hypodermic injection. Therefore, issues including needle-phobic, needle-stick injuries and inappropriate reuse of needles would hamper the further applications of these delivery platforms. Microneedles (MNs) as a potential alternative system for hypodermic needles can benefit from minimally invasive and self-administration. Recently, polymeric microneedle-mediated sustained release systems (MN@SRS) have opened up a new way for treatment of many diseases. Here, we reviewed the recent researches in MN@SRS for transdermal delivery, and summed up its typical design strategies and applications in various diseases therapy, particularly focusing on the applications in contraception, infection, cancer, diabetes, and subcutaneous disease. An overview of the present clinical translation difficulties and future outlook of MN@SRS was also provided.

Diving into 3D (bio)printing: A revolutionary tool to customize the production of drug and cell-based systems for skin delivery

The incorporation of 3D printing technologies in the pharmaceutical industry can revolutionize its R&D, by providing a simple and rapid method to produce tailored one-off batches, each with customized dosages, different compounds, shapes, sizes, and adjusted release rates. Particularly, this type of technology can be advantageous for the development of topical and transdermal drug delivery systems, including patches and microneedles. The use of both systems as drug carriers offers advantages over the oral administration, but the possibility of skin irritation and sensitization, and the high production costs, may hinder the expansion of this market. In this context, 3D printing, a high-resolution technique, allows the design of high quality, personalized, complex and sophisticated structures, thus reducing the production costs and improving the patient compliance. This review covers the 3D printing concept and discusses the relevance of this technology to the pharmaceutical industry, with a special focus on the development of topical and transdermal products - patches and microneedles. The potential of 3D bioprinting for skin applications is also presented, highlighting the development of patch-like skin constructs for wound and burn treatment, and skin equivalents for in vitro research and drug development. Several recent studies were selected to support the relevance of the subjects addressed herein. Additionally, the limitations of these printing technologies are discussed, including regulatory, quality and safety issues.

Wearable patch delivery system for artificial pancreas health diagnostic-therapeutic application: A review

The advanced stimuli-responsive approaches for on-demand drug delivery systems have received tremendous attention as they have great potential to be integrated with sensing and multi-functional electronics on a flexible and stretchable single platform (all-in-one concept) in order to develop skin-integration with close-loop sensation for personalized diagnostic and therapeutic application. The wearable patch pumps have evolved from reservoir-based to matrix patch and drug-in-adhesive (single-layer or multi-layer) type. In this review, we presented the basic requirements of an artificial pancreas, surveyed the design and technologies used in commercial patch pumps available on the market and provided general information about the latest wearable patch pump. We summarized the various advanced delivery strategies with their mechanisms that have been developed to date and representative examples. Mechanical, electrical, light, thermal, acoustic and glucose-responsive approaches on patch form have been successfully utilized in the controllable transdermal drug delivery manner. We highlighted key challenges associated with wearable transdermal delivery systems, their research direction and future development trends.

Hydrogels-based ophthalmic drug delivery systems for treatment of ocular diseases

An increasing number of people worldwide are affected by eye diseases, eventually leading to visual impairment or complete blindness. Conventional treatment involves the use of eye drops. However, these formulations often confer low ocular bioavailability and frequent dosing is required. Therefore, there is an urgent need to develop more effective drug delivery systems to tackle the current limitations. Hydrogels are multifunctional ophthalmic drug delivery systems capable of extending drug residence time and sustaining release of drugs. In this review, common ocular diseases and corresponding therapeutic drugs are briefly introduced. In addition, various types of hydrogels reported for ophthalmic drug delivery, including in-situ gelling hydrogels, contact lenses, low molecular weight supramolecular hydrogels, cyclodextrin/poly (ethylene glycol)-based supramolecular hydrogels and hydrogel-forming microneedles, are summarized. Besides, marketed hydrogel-based opthalmic formulations and clinical trials are also highlighted. Finally, critical considerations regarding clinical translation of biologics-loaded hydrogels are discussed.

Long-acting nanoparticle-loaded bilayer microneedles for protein delivery to the posterior segment of the eye

Treatment of neovascular ocular diseases involves intravitreal injections of therapeutic proteins using conventional hypodermic needles every 4-6 weeks. Due to the chronic nature of these diseases, these injections will be administrated to patients for the rest of their lives and their frequent nature can potentially pose a risk of sight-threatening complications and poor patient compliance. Therefore, we propose to develop nanoparticle (NP)-loaded bilayer dissolving microneedle (MN) arrays, to sustain delivery of protein drugs in a minimally invasive manner. In this research, a model protein, ovalbumin (OVA)-encapsulated PLGA NPs were prepared and optimised using a water-in-oil-in-water (W/O/W) double emulsion method. The impact of stabilisers and primary sonication time on the stability of encapsulated OVA was evaluated using an enzyme-linked immunosorbent assay (ELISA). Results showed that the lower primary sonication time was capable of sustaining release (77 days at 28.5% OVA loading) and improving the OVA bioactivity. The optimised NPs were then incorporated into a polymeric matrix to fabricate bilayer MNs and specifically concentrated into MN tips by high-speed centrifugation. Optimised bilayer MNs exhibited good mechanical and insertion properties and rapid dissolution kinetics (less than 3 min) in excised porcine sclera. Importantly, ex vivo transscleral distribution studies conducted using a multiphoton microscope confirmed the important function of MN arrays in the localisation of proteins and NPs in the scleral tissue. Furthermore, the polymers selected to prepare bilayer MNs and OVA NPs were determined to be biocompatible with retinal cells (ARPE-19). This delivery approach could potentially sustain the release of encapsulated proteins for more than two months and effectively bypass the scleral barrier, leading to a promising therapy for treating neovascular ocular diseases.

Build an implanted "arsenal": detachable microneedles for NIR-triggered cancer photothermo-chemotherapy

The current trend in tumor research is shifting from monotherapy to multimodal therapy. However, how to achieve on-demand drug delivery and minimize the invasiveness of treatment are still big challenges. Herein, we present a detachable microneedles (MNs) system, which consists of polycaprolactone (PCL) needles and polyvinylpyrrolidone/poly (vinyl alcohol) substrate, to build an implanted drug depot for on-demand photothermo-chemotherapy. Owing to the dissolvability of the substrate, detachable MNs can intradermally implant PCL needles loaded with photothermal conversion agent Prussian blue nanocubes (PB NCs) and chemotherapeutics doxorubicin hydrochloride (Dox·HCl). Once near-infrared light irradiates, PB NCs could translate light to local regional hyperthermia, which not only ablates cancer cells but also meltPCL to accelerate the diffusion of Dox·HCl. These MNs displayed a stable and repeatable photothermal effect under NIR irradiation. The ex vivo experiments using isolated swine skin demonstrated the as needed Dox·HCl delivery triggered by NIR light. Moreover, the robust antitumor efficacy of the MN system was proved in KB tumor-bearing nude mice under three timed NIR irradiation. Therefore, the developed detachable MNs which could build implanted "arsenal" for on-demand photothermo-chemotherapy have a bright future in tumor suppression.

Microneedles in Smart Drug Delivery

Significance: In biomedical setup, at large, and drug delivery, in particular, transdermal patches, hypodermal needles, and/or dermatological creams with the topical appliance are among the most widely practiced routes for transdermal drug delivery. Owing to the stratum corneum layer of the skin, traditional drug delivery methods are inefficient, and the effect of the administered therapeutic cues is limited. Recent Advances: The current advancement at the microlevel and nanolevel has revolutionized the drug delivery sector. Particularly, various types of microneedles (MNs) are becoming popular for drug delivery applications because of safety, patient compliance, and smart action. Critical Issues: Herein, we reviewed state-of-the-art MNs as a smart and sophisticated drug delivery approach. Following a brief introduction, the drug delivery mechanism of MNs is discussed. Different types of MNs, that is, solid, hollow, coated, dissolving, and hydrogel forming, are discussed with suitable examples. The latter half of the work is focused on the applied perspective and clinical translation of MNs. Furthermore, a detailed overview of clinical applications and future perspectives is also included in this review. Future Directions: Regardless of ongoing technological and clinical advancement, the focus should be diverted to enhance the efficacy and strength of MNs. Besides, the possible immune response or interference should also be avoided for successful clinical translation of MNs as an efficient drug delivery system.

Temporal dynamics of intradermal cytokine response to tuberculin in Mycobacterium bovis BCG-vaccinated cattle using sampling microneedles

Bovine tuberculosis (bTB) is a disease of livestock with severe and worldwide economic, animal welfare and zoonotic consequences. Application of test-and-slaughter-based control polices reliant on tuberculin skin testing has been the mainstay of bTB control in cattle. However, little is known about the temporal development of the bovine tuberculin skin test response at the dermal sites of antigen injection. To fill this knowledge gap, we applied minimally-invasive sampling microneedles (SMNs) for intradermal sampling of interstitial fluid at the tuberculin skin test sites in Mycobacterium bovis BCG-vaccinated calves and determined the temporal dynamics of a panel of 15 cytokines and chemokines in situ and in the peripheral blood. The results reveal an orchestrated and coordinated cytokine and local chemokine response, identified IL-1RA as a potential soluble biomarker of a positive tuberculin skin response, and confirmed the utility of IFN-γ and IP-10 for bTB detection in blood-based assays. Together, the results highlight the utility of SMNs to identify novel biomarkers and provide mechanistic insights on the intradermal cytokine and chemokine responses associated with the tuberculin skin test in BCG-sensitized cattle.

Hollow microneedles: A perspective in biomedical applications

Microneedles (MN) have the potential to become a highly progressive device for both drug delivery and monitoring purposes as they penetrate the skin and pierce the stratum corneum barrier, allowing the delivery of drugs in the viable skin layers and the extraction of body fluids. Despite the many years of research and the different types of MN developed, only hollow MN have reached the pharmaceutical market under the path of medical devices. Therefore, this review focuses on hollow MN, materials and methods for their fabrication as well as their application in drug delivery, vaccine delivery and monitoring purposes. Furthermore, novel approaches for the fabrication of hollow MN are included as well as prospects of microneedle-based products on the market.

Layered dissolving microneedles as a need-based delivery system to simultaneously alleviate skin and joint lesions in psoriatic arthritis

Psoriatic arthritis (PsA) is a complicated psoriasis comorbidity with manifestations of psoriatic skin and arthritic joints, and tailoring specific treatment strategies for simultaneously delivering different drugs to different action sites in PsA remains challenging. We developed a need-based layered dissolving microneedle (MN) system loading immunosuppressant tacrolimus (TAC) and anti-inflammatory diclofenac (DIC) in different layers of MNs, i.e., TD-MN, which aims to specifically deliver TAC and DIC to skin and articular cavity, achieving simultaneous alleviation of psoriatic skin and arthritic joint lesions in PsA. In vitro and in vivo skin permeation demonstrated that the inter-layer retained TAC within the skin of ∼100 μm, while the tip-layer delivered DIC up to ∼300 μm into the articular cavity. TD-MN not only efficiently decreased the psoriasis area and severity index scores and recovered the thickened epidermis of imiquimod-induced psoriasis but also alleviated carrageenan/kaolin-induced arthritis even better than DIC injection through reducing joint swelling, muscle atrophy, and cartilage destruction. Importantly, TD-MN significantly inhibited the serum TNF-α and IL-17A in psoriatic and arthritic rats. The results support that this approach represents a promising alternative to multi-administration of different drugs for comorbidity, providing a convenient and effective strategy for meeting the requirements of PsA treatment.

Microneedle-mediated transdermal drug delivery for treating diverse skin diseases

Transdermal drug delivery is an attractive route for dermatological disease therapy because it can directly target the lesion site on the skin, reduce adverse reactions associated with systemic administration, and improve patient compliance. However, the stratum corneum, as the main skin barrier, severely limits transdermal drug penetration, with compromised bioavailability. Microneedles (MNs), which are leveraged to markedly improve the penetration of therapeutic agents by piercing the stratum corneum and creating hundreds of reversible microchannels in a minimally invasive manner, have been envisioned as a milestone for effective transdermal drug delivery, especially for superficial disease therapy. Here, the emergence of versatile MNs for the transdermal delivery of various drugs is reviewed, particularly focusing on the application of MNs for the treatment of diverse skin diseases, including superficial tumors, scars, psoriasis, herpes, acne, and alopecia. Additionally, the promises and challenges of the widespread translation of MN-mediated transdermal drug delivery in the dermatology field are summarized.

Drug delivery device for the inner ear: ultra-sharp fully metallic microneedles

Drug delivery into the inner ear is a significant challenge due to its inaccessibility as a fluid-filled cavity within the temporal bone of the skull. The round window membrane (RWM) is the only delivery portal from the middle ear to the inner ear that does not require perforation of bone. Recent advances in microneedle fabrication enable the RWM to be perforated safely with polymeric microneedles as a means to enhance the rate of drug delivery from the middle ear to the inner ear. However, the polymeric material is not biocompatible and also lacks the strength of other materials. Herein we describe the design and development of gold-coated metallic microneedles suitable for RWM perforation. When developing microneedle technology for drug delivery, we considered three important general attributes: (1) high strength and ductility material, (2) high accuracy and precision of fabrication, and (3) broad design freedom. We developed a hybrid additive manufacturing method using two-photon lithography and electrochemical deposition to fabricate ultra-sharp gold-coated copper microneedles with these attributes. We refer to the microneedle fabrication methodology as two-photon templated electrodeposition (2PTE). We demonstrate the use of these microneedles by inducing a perforation with a minimal degree of trauma in a guinea pig RWM while the microneedle itself remains undamaged. Thus, this microneedle has the potential literally of opening the RWM for enhanced drug delivery into the inner ear. Finally, the 2PTE methodology can be applied to many different classes of microneedles for other drug delivery purposes as well the fabrication of small scale structures and devices for non-medical applications. Graphical Abstract Fully metallic ultra-sharp microneedle mounted at end of a 24-gauge stainless steel blunt syringe needle tip: (left) Size of microneedle shown relative to date stamp on U.S. one-cent coin; (right) Perforation through guinea pig round window membrane introduced with microneedle.

Transdermal Delivery Systems for Biomolecules

Purpose

The present review article focuses on highlighting the main technologies used as tools that improve the delivery of transdermal biomolecules, addressing them from the point of view of research in the development of transdermal systems that use physical and chemical permeation enhancers and nanocarrier systems or a combination of them.

Results

Transdermal drug delivery systems have increased in importance since the late 1970s when their use was approved by the Food and Drug Administration (FDA). They appeared to be an alternative resource for the administration of many potent drugs. The first transdermal drug delivery system used for biomolecules was for the treatment of hormonal disorders. Biomolecules have been used primarily in many treatments for cancer and diabetes, vaccines, hormonal disorders, and contraception.

Conclusions

The latest technologies that have used such transdermal biomolecule transporters include electrical methods (physical penetration enhancers), some chemical penetration enhancers and nanocarriers. All of them allow the maintenance of the physical and chemical properties of the main proteins and peptides through these clinical treatments, allowing their efficient storage, transport, and release and ensuring the achievement of their target and better results in the treatment of many diseases.

Graphical abstract

Microneedles for painless transdermal immunotherapeutic applications

Immunotherapy has recently garnered plenty of attention to improve the clinical outcomes in the treatment of various diseases. However, owing to the dynamic nature of the immune system, this approach has often been challenged by concerns regarding the lack of adequate long-term responses in patients. The development of microneedles (MNs) has resulted in the improvement and expansion of immuno-reprogramming strategies due to the housing of high accumulation of dendritic cells, macrophages, lymphocytes, and mast cells in the dermis layer of the skin. In addition, MNs possess many outstanding properties, such as the ability for the painless traverse of the stratum corneum, minimal invasiveness, facile fabrication, excellent biocompatibility, convenient administration, and bypassing the first pass metabolism that allows direct translocation of therapeutics into the systematic circulation. These advantages make MNs excellent candidates for the delivery of immunological biomolecules to the dermal antigen-presenting cells in the skin with the aim of vaccinating or treating different diseases, such as cancer and autoimmune disorders, with minimal invasiveness and side effects. This review discusses the recent advances in engineered MNs and tackles limitations relevant to traditional immunotherapy of various hard-to-treat diseases.

Trends of microneedle technology in the scientific literature, patents, clinical trials and internet activity

The powerful and intriguing idea that drives the emerging technology of microneedles-shrinking the standard needle to a micron scale-has fostered an entire field of microneedle study and subsequent exponential growth in research and product development. Originally enabled by microfabrication tools derived from the microelectronic industry, microneedles are now produced through a number of methods in a variety of forms including solid, coated, dissolvable, and hollow microneedles. They are used to deliver a broad spectrum of molecules, including small molecules, biomolecules, and vaccines, as well as various forms of energy into the skin, eye, and other tissues. Microneedles are also being exploited for use in diagnostics, as well as additional medical, cosmetic, and other applications. This review elucidates the relative roles of different aspects of microneedle technology development, as shown through scientific papers, patents, clinical studies, and internet/social media activity. Considering >1000 papers, 750 patents, and almost 80 clinical trials, we analyze different attributes of microneedles such as usage of microneedles, types of microneedles, testing environment, types of patent claims, and phases of clinical trials, as well as which institutions and people in academia and industry from different locations and in different journals are publishing, patenting, and otherwise studying the potential of microneedles. We conclude that there is robust and growing activity in the field of microneedles; the technology is rapidly developing and being used for novel applications to benefit human health and well-being.

Polymeric-based microneedle arrays as potential platforms in the development of drugs delivery systems

BACKGROUND

Microscopic patches as quite promising platforms in transdermal drug delivery suffer from conventional injections. In other hand, a wide range of pharmacokinetics, ranging from fast oral administration to sustained drug delivery, can be implemented with the help of microneedle arrays (MNAs).

AIM OF REVIEW

Hence, in this paper, we overviewed different kinds of MNAs such as solid/coated, hollow, porous, hydrogel/swellable, and merged-tip geometry followed by introducing different types of material (silicon, glass, ceramics, dissolving and biodegradable polymers, and hydrogel) used for fabrication of MNAs. Afterwards, some conventional and brand-new simple and customizable MN mold fabrication techniques were surveyed. Polymeric MNAs have received a great deal of attention due to their potential biocompatibility and biodegradability in comparison to other materials. Therefore, we also covered different kinds of polymers such as hydrogel/swellable, dissolving and biodegradable analogues used for the development of MNAs as potential candidates in drug delivery systems (DDSs). Finally, we discussed different challenges and future perspectives in the aspect of MNAs-based drug delivery platforms.

KEY SCIENTIFIC CONCEPTS OF REVIEW

This review may provide guidelines for the rational design of polymeric MNAs-based DDSs for promising programmable drug release and enhanced therapeutic effect.

Modeling drug transport within the viable skin - a review

INTRODUCTION

In the past, mathematical modeling of the transport of transdermal drugs has been primarily focused on the stratum corneum. However, the development of pharmaceutical technologies, such as chemical enhancers, iontophoresis, and microneedles, has led to two outcomes; an increase in permeability in the stratum corneum or the ability to negate the layer entirely. As a result, these outcomes have made the transport of a solute in the viable skin far more critical when studying transdermal drug delivery.

AREAS COVERED

The review will explicitly show the various attempts to model drug transport within the viable skin. Furthermore, a brief review will be conducted on the different models that explain stratum corneum transport, microneedle dynamics and estimation of the diffusion coefficient.

EXPERT OPINION

Future development of mathematical models requires the focus to be changed from traditional diffusion-based tissue models to more sophisticated three-dimensional models that incorporate the physiology of the skin.

Vat photopolymerization 3D printing for advanced drug delivery and medical device applications

Three-dimensional (3D) printing is transforming manufacturing paradigms within healthcare. Vat photopolymerization 3D printing technology combines the benefits of high resolution and favourable printing speed, offering a sophisticated approach to fabricate bespoke medical devices and drug delivery systems. Herein, an overview of the vat polymerization techniques, their unique applications in the fields of drug delivery and medical device fabrication, material examples and the advantages they provide within healthcare, is provided. The challenges and drawbacks presented by this technology are also discussed. It is forecast that the adoption of 3D printing could pave the way for a personalised health system, advancing from traditional treatments pathways towards digital healthcare.

Progress and perspective of microneedle system for anti-cancer drug delivery

Transdermal drug delivery exhibited encouraging prospects, especially through superficial drug administration routes. However, only a few limited lipophilic drug molecules could cross the skin barrier, those are with low molecular weight and rational Log P value. Microneedles (MNs) can overcome these limitations to deliver numerous drugs into the dermal layer by piercing the outermost skin layer of the body. In the case of superficial cancer treatments, topical drug administration faces severely low transfer efficiency, and systemic treatments are always associated with side effects and premature drug degradation. MN-based systems have achieved excellent technical capabilities and been tested for pre-clinical chemotherapy, photothermal therapy, photodynamic therapy, and immunotherapy. In this review, we will focus on the features, progress, and opportunities of MNs in the anticancer drug delivery system. Then, we will discuss the strategies and advantages in these works and summarize challenges, perspectives, and translational potential for future applications.

Advances in Antimicrobial Microneedle Patches for Combating Infections

Skin infections caused by bacteria, viruses and fungi are difficult to treat by conventional topical administration because of poor drug penetration across the stratum corneum. This results in low bioavailability of drugs to the infection site, as well as the lack of prolonged release. Emerging antimicrobial transdermal and ocular microneedle patches have become promising medical devices for the delivery of various antibacterial, antifungal, and antiviral therapeutics. In the present review, skin anatomy and its barriers along with skin infection are discussed. Potential strategies for designing antimicrobial microneedles and their targeted therapy are outlined. Finally, biosensing microneedle patches associated with personalized drug therapy and selective toxicity toward specific microbial species are discussed.

Dissolving Microneedles with Spatiotemporally controlled pulsatile release Nanosystem for Synergistic Chemo-photothermal Therapy of Melanoma

High aggressiveness and recurrence of melanoma tumors require multiple systemic drug administrations, causing discomfort and severe side effects to the patients. Topical treatment strategies that provide repetitively controllable and precise drug administrations will greatly improve treatment effects.

Methods: In this study, a spatiotemporally controlled pulsatile release system, which combined dissolving microneedles (DMNs) and thermal-sensitive solid lipid nanoparticles (SLNs), was constructed to realize multiple doses of dual-modal chemo-photothermal therapy in a single administration. Paclitaxel (PTX) and photothermal agent IR-780 were encapsulated into SLNs and were concentrated in the tips of DMNs (PTX/IR-780 SLNs @DMNs). Equipped with several needles, the DMN patch could be directly inserted into the tumor site and provide a stable “Zone accumulation” to constrain the PTX/IR-780 SLNs at the tumor site with uniform distribution.

Results:In vitro experiments showed that after irradiation with near-infrared light, the PTX/IR-780 SLNs gradually underwent phase transition, thereby accelerating the release of PTX. When irradiation was switched off, the PTX/IR-780 SLNs cooled to re-solidify with limited drug release. Compared with intravenous and intratumoral injections, very few SLNs from PTX/IR-780 SLNs @DMNs were distributed into other organs, resulting in enhanced bioavailability at the tumor site and good safety. In vivo analysis revealed that PTX/IR-780 SLNs @DMNs exhibited significant anti-tumor efficacy. In particular, the primary tumor was completely eradicated with a curable rate of 100% in 30 days and the highest survival rate of 66.67% after 100 days of treatment.

Conclusion: Herein, we developed a DMN system with a unique spatiotemporally controlled pulsatile release feature that provides a user-friendly and low-toxicity treatment route for patients who need long-term and repeat treatments.

Nanoparticles-encapsulated polymeric microneedles for transdermal drug delivery

Polymeric microneedles (MNs) have been leveraged as a novel transdermal drug delivery platform for effective drug permeation, which were widely used in the treatment of various diseases. However, issues including limited loading capacity of hydrophobic drugs, uncontrollable drug release rates, and monotonic therapeutic strategy hamper the further application of polymeric MNs. As a recent emerging research topic, drawing inspiration from the ways that nanomedicine integrated with MNs have opened new avenues for disease therapy. In this review, we examined the recent studies employing nanoparticles (NPs)-encapsulated polymeric MNs (NPs@MNs) for transdermal delivery of various therapeutic cargos, particularly focused on the application of NPs@MNs for diabetes therapy, infectious disease therapy, cancer therapy, and other dermatological disease therapy. We also provided an overview of the clinical potential and future translation of NPs@MNs.

Microneedle-Based Delivery: An Overview of Current Applications and Trends

Microneedle arrays (MNA) are considered as one of the most promising resources to achieve systemic effects by transdermal delivery of drugs. They are designed as a minimally invasive, painless system which can bypass the stratum corneum, overcoming the potential drawbacks of subcutaneous injections and other transdermal delivery systems such as chemical enhancers, nano and microparticles, or physical treatments. As a trendy field in pharmaceutical and biomedical research, its applications are constantly evolving, even though they are based on very well-established techniques. The number of molecules administered by MNA are also increasing, with insulin and vaccines administration being the most investigated. Furthermore, MNA are being used to deliver cells and applied in other organs and tissues like the eyes and buccal mucosae. This review intends to offer a general overview of the current state of MNA research, focusing on the strategies, applications, and types of molecules delivered recently by these systems. In addition, some information about the materials and manufacturing processes is presented and safety data is discussed.

Coated polymeric needles for rapid and deep intradermal delivery

Two groups of single polymeric needles (crosslinked Gantrez®S-97 and poly(ethylene glycol)) of different lengths (2 mm and 4.5 mm) with defined base widths were fabricated and tested in terms of their mechanical strength and insertion abilities using two skin models (Parafilm® and porcine skin). For the shorter needles, application of an axial force (32 N) resulted in a height reduction of approximately 80%. Nonetheless, around 80% of total needle length was successfully inserted in both skin models. Optical coherence tomography showed that base width highly impacted insertion capabilities of the longer needles as only the thicker one (0.922 mm width at base) inserted into porcine skin. Additionally, needles were coated with rhodamine B and inserted into porcine skin. In comparison to a control, penetration depth of the model drug increased 2-fold for short and 4.5-fold for long needles, respectively. Moreover, quantification across skin sections showed that shorter needles delivered 10 μg of the compound in a depth of 1.5–2.0 mm while long needles were capable of delivering 5 μg into even deeper skin layers (2.0–3.0 mm), confirming the potential of coated polymeric needles for rapid and deep intradermal delivery.

Effect of Ultrasound Intensity and Mode on Piroxicam Transport Across Three-Dimensional Skin Equivalent Epiderm™

BACKGROUND

Transdermal drug delivery has many advantages compared to other routes. However, the barrier function of the stratum corneum limits the use of the skin as an administrative route for medications. Different methods were investigated to alter the barrier function of the stratum corneum and it was found that applying different ultrasound waves could enhance the skin's permeability.

OBJECTIVE

The aim of this work is to study the effect of ultrasonic waves on the alteration of skin natural barrier function, to improve the permeability of the skin to Piroxicam using three-dimension skin (EpiDermTM) as a skin model for the investigation.

METHOD

The effect of ultrasound at 1 MHz and 20 kHz on the permeation of Piroxicam across the three-dimensional skin equivalent using a Franz diffusion cell, was evaluated and the concentration of Piroxicam in the receiving compartment was determined using liquid chromatography method.

RESULTS

The permeation of Piroxicam enhanced by 199% when therapeutic ultrasound at 1 MHz frequency was used. Significant permeation enhancement was also found upon utilizing low frequency sonophoresis at 20 kHz (427%) with no apparent damage to the membrane.

CONCLUSION

Sonophoresis has a positive effect on enhancing skin permeability. The enhancement level was largely dependent on the sonication factors; frequency, intensity and length of treatment. Multiple mechanisms of action might be involved in permeation improvement of the piroxicam molecule. Those mechanisms are largely dependent on the ultrasonic conditions.

State-of-the-art methods in clinical intracochlear drug delivery

PURPOSE OF REVIEW

Increasing awareness and prevalence of disorders in hearing and balance have placed emphasis on treatment strategies. With the rapid evolution in molecular, gene, and nanotechnology, alternate delivery methods have advanced intracochlear drug delivery. This review aims to raise awareness of recent developments in technologies to augment current clinical practices.

RECENT FINDINGS

Intracochlear drug delivery research has expanded with the familiarity and accessibility to cochlear implantation. Various therapeutics are closely studied for both safety and efficacy as well as biologic effect. Agents including neurotrophins, antiapoptotics, cell therapy, gene therapy, and anti-inflammatory drugs are on the forefront of preclinical research. Cochlear implant electrode modification and drug administration at the time of implantation is a major focus of research. Improvements in study design have focused on overcoming barriers including elucidating the role of the blood-perilymph barrier.

SUMMARY

Inner ear drug delivery methods include systemic, intratympanic, and intracochlear administration. Therapeutic technologies aim to overcome delivery barriers and to improve overall biologic effect while minimizing toxicity. Precision of drug application through intratympanic and intracochlear administration with minimal trauma is the future of inner ear drug development.

Highly potent intradermal vaccination by an array of dissolving microneedle polypeptide cocktails for cancer immunotherapy

Despite recent advances in cancer therapy using vaccines, the efficacy of vaccine regimens remains to be improved. Cutaneous transportation of biomolecules, particularly DNA vaccines, has potentially improved the therapeutic efficacy and has been found to be an appealing approach in cancer immunotherapy. Nevertheless, the effectiveness of transdermal vaccination is limited by the lack of efficacious immune stimulation. Here, to elicit strong immunogenicity in target cells, we propose an array of dissolving microneedle cocktails for pain-free implantation and triggered release of vaccines and adjuvants at cutaneous tissues. The microneedle cocktails comprising a bioresorbable polypeptide matrix with a nanopolyplex, which include cationic amphiphilic conjugates with ovalbumin-expressing plasmid OVA (pOVA) and immunostimulant-polyinosinic:polycytidylic acid (poly(I:C)), were prepared using a one-pot synthesis. The cationic nanopolyplex effectively transported pOVA and poly(I:C) into the intracellular compartments of dendritic cells and macrophages. Cutaneous implantation of microneedle cocktails on mice elicits a stronger antigen-specific antibody response than subcutaneous administration of the microneedle-free nanopolyplex. Compared with traditional vaccination, the dissolving microneedle cocktails enhanced the antibody recall memory after challenge; remarkably, the cocktail-based therapeutic vaccination also resulted in enhanced lung clearance of cancer cells. The dissolving microneedle cocktail therapy based on the triggered release of immunomodulators and adjuvants synergistically augmented the therapeutic effect in B16/OVA melanoma tumors.