Improved Insulin Pharmacokinetics Using a Novel Microneedle Device for Intradermal Delivery in Patients with Type 2 Diabetes

Current Status of Microneedle Array Technology for Therapeutic Delivery: From Bench to Clinic

In recent years, microneedle (MN) patches have emerged as an alternative technology for transdermal delivery of various drugs, therapeutics proteins, and vaccines. Therefore, there is an urgent need to understand the status of MN-based therapeutics. The article aims to illustrate the current status of microneedle array technology for therapeutic delivery through a comprehensive review. However, the PubMed search was performed to understand the MN's therapeutics delivery status. At the same time, the search shows the number no of publications on MN is increasing (63). The search was performed with the keywords "Coated microneedle," "Hollow microneedle," "Dissolvable microneedle," and "Hydrogel microneedle," which also shows increasing trend. Similarly, the article highlighted the application of different microneedle arrays for treating different diseases. The article also illustrated the current status of different phases of MN-based therapeutics clinical trials. It discusses the delivery of different therapeutic molecules, such as drug molecule delivery, using microneedle array technology. The approach mainly discusses the delivery of different therapeutic molecules. The leading pharmaceutical companies that produce the microneedle array for therapeutic purposes have also been discussed. Finally, we discussed the limitations and future prospects of this technology.

Anti-Obesity Drug Delivery Systems: Recent Progress and Challenges

Obesity has reached an epidemic proportion in the last thirty years, and it is recognized as a major health issue in modern society now with the possibility of serious social and economic consequences. By the year 2030, nearly 60% of the global population may be obese or overweight, which emphasizes a need for novel obesity treatments. Various traditional approaches, such as pharmacotherapy and bariatric surgery, have been utilized in clinical settings to treat obesity. However, these methods frequently show the possibility of side effects while remaining ineffective. There is, therefore, an urgent need for alternative obesity treatments with improved efficacy and specificity. Polymeric materials and chemical strategies are employed in emerging drug delivery systems (DDSs) to enhance therapy effectiveness and specificity by stabilizing and controlling the release of active molecules such as natural ingredients. Designing DDSs is currently a top priority research objective with an eye towards creating obesity treatment approaches. In reality, the most recent trends in the literature demonstrate that there are not enough in-depth reviews that emphasize the current knowledge based on the creation and design of DDSs for obesity treatment. It is also observed in the existing literature that a complex interplay of different physical and chemical parameters must be considered carefully to determine the effectiveness of the DDSs, including microneedles, for obesity treatment. Additionally, it is observed that these properties depend on how the DDS is synthesized. Although many studies are at the animal-study stage, the use of more advanced DDS techniques would significantly enhance the development of safe and efficient treatment approaches for obese people in the future. Considering these, this review provides an overview of the current anti-obesity treatment approaches as well as the conventional anti-obesity therapeutics. The article aims to conduct an in-depth discussion on the current trends in obesity treatment approaches. Filling in this knowledge gap will lead to a greater understanding of the safest ways to manage obesity.

Immune Response of Inactivated Rabies Vaccine Inoculated via Intraperitoneal, Intramuscular, Subcutaneous and Needle-Free Injection Technology-Based Intradermal Routes in Mice

Inoculation routes may significantly affect vaccine performance due to the local microenvironment, antigen localization and presentation, and, therefore, final immune responses. In this study, we conducted a head-to-head comparison of immune response and safety of inactivated rabies vaccine inoculated via intraperitoneal (IP), intramuscular (IM), subcutaneous (SC) and needle-free injection technology-based intradermal (ID) routes in ICR mice. Immune response was assessed in terms of antigen-specific antibodies, antibody subtypes and neutralizing antibodies for up to 28 weeks. A live rabies virus challenge was also carried out to evaluate vaccine potency. The dynamics of inflammatory cell infiltration at the skin and muscle levels were determined via histopathological examination. The kinetics and distribution of a model antigen were also determined by using in vivo fluorescence imaging. Evidence is presented that the vaccine inoculated via the ID route resulted in the highest antigen-specific antibody and neutralizing antibody titers among all administration routes, while IP and IM routes were comparable, followed by the SC route. Antibody subtype analysis shows that the IP route elicited a Th1-biased immune response, while SC and IM administration elicited a prominent Th2-type immune response. Unexpectedly, the ID route leads to a balanced Th1 and Th2 immune response. In addition, the ID route conferred effective protection against lethal challenge with 40 LD50 of the rabies CVS strain, which was followed by IP and IM routes. Moreover, a one-third dose of the vaccine inoculated via the ID route provided comparable or higher efficacy to a full dose of the vaccine via the other three routes. The superior performance of ID inoculation over other routes is related to longer local retention at injection sites and higher lymphatic drainage. Histopathology examination reveals a transient inflammatory cell infiltration at ID and IM injection sites which peaked at 48 h and 24 h, respectively, after immunization, with all side effects disappearing within one week. These results suggest that needle-free injection technology-based ID inoculation is a promising strategy for rabies vaccination in regard to safety and efficacy.

Effects of Intradermal Administration Volume Using a Hollow Microneedle on the Pharmacokinetics of Fluorescein Isothiocyanate Dextran (M.W. 4,000)

PURPOSE

Hollow microneedles (hMNs) have been gaining attention as a tool to enable the intradermal (i.d.) administration of pharmaceutical products. However, few reports have examined the effect of administration volume on distribution in the skin and pharmacokinetics parameters after i.d. injection. In the present study, a model middle molecular weight compound, fluorescein isothiocyanate dextran (M.W. 4,000, FD-4), was selected, and blood concentration-time profiles after i.d. and subcutaneous (s.c.) injections with different administration volumes were compared.

METHODS

FD-4 solution was injected i.d. using a hMN or injected s.c. with a 27 G needle. Pharmacokinetics and dermatokinetics of FD-4 were analyzed using a compartment model. The skin distribution of iodine, as an X ray tracer, was used to evaluate drug disposition.

RESULTS

With the administered drug assumed to be absorbed from the broad injection site into blood vessels in the upper and lower dermis by rapid (krapid) and slow (kslow) first-order absorption rate constants, respectively, better agreement of observed and theoretical values was obtained. Furthermore, the fraction, F, of the administered dose absorbed with krapid decreased with the increase in injection volume after i.d. injection, although the pharmacokinetics parameters were almost the same regardless of administration volume after s.c. injection.

CONCLUSION

The drug distribution in the skin may be related to the obtained pharmacokinetics parameters suggested that the number of needles in the MN system and the total administration volume should be considered in designing hMN systems. The present results provide useful information that may support effective drug delivery with hMNs.

Unmanned Aerial Vehicle Mediated Drug Delivery for First Aid

Timely administration of key medications toward patients with sudden diseases is critical to saving lives. However, slow transport of first-aid therapeutics and the potential absence of trained people for drug usage can lead to severe injuries or even death. Herein, an unmanned aerial vehicle (UAV)-mediated first-aid system for targeted delivery (uFAST) is developed. It allows unattended administration of emergency therapeutics-loaded transdermal microneedle (MN) patches toward patients to relieve symptoms by a contact-triggered microneedle applicator (CTMA). The implementability and safety of the uFAST for first aid is demonstrated in a severe hypoglycemic pig model by automatically delivering a glucagon patch with immediate and bioresponsive dual release modes. This platform technique may facilitate the development of UAV-mediated first-aid treatments for other sudden diseases.

Needle Technology for Insulin Administration: A Century of Innovation

Innovations in syringe and pen needle (PN) technology over the last 100 years have led to important advances in insulin delivery for people with diabetes, paralleling the strides made in developing recombinant DNA human insulin and insulin analogs with varying onset and duration of action. In this review, the history of advances in insulin delivery is described, focusing on progress in syringe, needle, and PN technologies. The early glass and metal syringes that required sterilization by boiling have been replaced by disposable, single-use syringes or pens with clear labeling for precise insulin dosing. The early needles ranging in length from 19 to 26 mm that required manual sharpening against a whetstone have been replaced by syringe needles of 6 mm and PNs of 4 mm in length as slender as 34 gauge. Imaging studies using ultrasound and computed tomography measured the thickness of skin and subcutaneous tissue layers to show feasibility of targeted insulin administration with shorter needles. These developments, coupled with innovations in needle/PN wall and tip structure, have led to improved injection experience for people with diabetes. It is also important to acknowledge the role of injection technique education, together with these advances in injection technology, for improving clinical outcomes and patient satisfaction. With continued projected growth of diabetes prevalence, particularly in developing countries where expensive and complex insulin delivery systems may not be practical, insulin syringes and pens will continue to serve as reliable and cost-effective means of insulin delivery for people with diabetes.

The clinical and translational prospects of microneedle devices, with a focus on insulin therapy for diabetes mellitus as a case study

Microneedles have the clinical advantage of being able to deliver complex drugs across the skin in a convenient and comfortable manner yet haven't successfully transitioned to medical practice. Diabetes mellitus is a complicated disease, which is commonly treated with multiple daily insulin injections, contributing to poor treatment adherence. Firstly, this review determines the clinical prospect of microneedles, alongside considerations that ought to be addressed before microneedle technology can be translated from bench to bedside. Thereafter, we use diabetes as a case study to consider how microneedle-based-technology may be successfully harnessed. Here, publications referring to insulin microneedles were evaluated to understand whether insertion efficiency, angle of insertion, successful dose delivery, dose adjustability, material biocompatibility and therapeutic stability are being addressed in early stage research. Moreover, over 3,000 patents from 1970-2019 were reviewed with the search term '"microneedle" AND "insulin"' to understand the current status of the field. In conclusion, the reporting of early stage microneedle research demonstrated a lack of consistency relating to the translational factors addressed. Additionally, a more rational design, based on a patient-centred approach is required before microneedle-based delivery systems can be used to revolutionise the lives of people living with diabetes following regulatory approval.

Long-acting injectable formulation technologies: Challenges and opportunities for the delivery of fragile molecules

INTRODUCTION

The development of long acting injectables (LAIs) for protein and peptide therapeutics has been a key challenge over the last 20 years. If these molecules offer advantages due to their high specificity and selectivity, their controlled release may confer several additional benefits in terms of extended half-life, local delivery, and patient compliance.

AREA COVERED

This manuscript aims to give an overview of peptide and protein based LAIs from an industrial perspective, describing both approved and promising technologies (with exceptions of protein engineering strategies and devices), their advantages and potential improvements to aid their access to the market.

EXPERT OPINION

Many LAIs have been developed for peptides, with formulations on the market for several decades. On the contrary, LAIs for proteins are still far from the market and issues related to manufacturing and sterilization of these products still need to be overcome. In situ forming depots (ISFDs), whose simple manufacturing conditions and easy administration procedures (without reconstitution) are strong advantages, appear as one of the most promising technologies for the delivery of these molecules. In this regard, the approval of ELIGARD® in the early 2000's (which still requires a complex reconstitution process), paved the way for the development of second-generation, ready-to-use ISFD technologies like BEPO® and FluidCrystal®.

A Comparison of Flow- and Pressure-Controlled Infusion Strategies for Microneedle-based Transdermal Drug Delivery

Microneedle-based transdermal drug delivery is considered an attractive alternative to conventional injections using hypodermic needles due to its minimally invasive and painless nature; this has the potential to improve patient adherence to medication regimens. Hollow microneedles (MNs) are sharp, sub-millimeter protrusions with a channel that serves as a fluidic interface with the skin. This technology could be coupled with micro-pumps, embedded sensors, actuators and electronics to create Micro Transdermal Interface Platforms - smart, wearable infusion systems capable of delivering precise microdoses over a prolonged period. Using 500 µm tall hollow microneedles, ex-vivo human skin and a customized application/retraction device, this work focuses on comparing two infusion control strategies, namely 'set pressure' (SP) and 'set flow' (SF) infusion. It was found that flow-controlled infusion was capable of delivering higher volumes than pressure-driven delivery, and a mean volume of 3.8 mL was delivered using a set flowrate of 50 µL/minute. This suggests that flow driven delivery is a better control strategy and confirms that MN array retraction is beneficial for transdermal MN infusion.

Repeated insulin injection without site rotation affects skin thickness - ultrasonographic and histological evaluation

AIMS/INTRODUCTION

The influence of repeated insulin injection on subcutaneous tissue is known, but its impact on the skin is unclear. Therefore, this study aimed to elucidate the impact of repeated insulin injections on the skin.

MATERIAL AND METHODS

The properties of the skin and the subcutaneous tissue were evaluated in 52 insulin-treated adult patients with diabetes with abnormal findings at the site of self-injection (36 with subcutaneous nodules, 16 with suspected subcutaneous tissue induration) by ultrasonography. In all subjects, both normal and abnormal areas were examined. In addition, skin biopsies were performed in four subjects.

RESULTS

The skin thickness of the normal and abnormal skin sites was 1.95 (1.60, 2.50) and 2.80 (2.27, 3.30) mm, respectively (median (first quartile, third quartile)), (P < 0.001). The biopsy specimens revealed slightly thickened and tight bundles of collagen in the dermis. Three patients had amyloid deposits in the subcutaneous tissue, and one also showed these in the dermis. These were positively stained for insulin antibody.

CONCLUSIONS

Repeated insulin injection procedures result in skin thickening. Increased collagen fibers and possibly amyloid deposition in the dermis may be involved. The results reaffirmed the importance of appropriate site rotation in insulin injection and revealed the usefulness of ultrasonographic skin examination in evaluating the self-injection procedure.

Does Food Affect the Pharmacokinetics of Non-orally Delivered Drugs? A Review of Currently Available Evidence

The food effects for orally administered drugs have been widely investigated and reviewed. In contrast, our knowledge of food effects for non-orally administered drugs is scarce. In this review paper, we did a literature survey to collect clinical food effect data for non-orally administered drugs. Our survey retrieved 18 drugs, including thirteen intravenously (IV), two subcutaneously (SC), one intradermally (ID), one pulmonary, and one rectally administered drug. The food effect data show that food intake can increase the absorption of SC and ID administered peptides and proteins with MW < 30 kDa by 30-50%. On the other hand, food intake can increase the elimination of IV and inhaled drugs with moderate and high hepatic extraction and reduce drug exposure by up to 35%. The food effect knowledge can be used to mitigate potential efficacy and safety risks of non-orally administered drugs.

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.

Advances of microneedles in hormone delivery

The skin is recognized as a potential target for local and systemic drug delivery and hormone. However, the transdermal route of drug administration seems to be limited by substantial barrier properties of the skin. Recently, delivering hormone via the skin by transdermal patches is a big challenge because of the presence of the stratum corneum that prevents the application of hormone via this route. In order to overcome the limitations, microneedle (MN), consisting of micro-sized needles, are a promising approach to drill the stratum corneum and release hormone into the dermis via a minimal-invasive route. This review aimed to highlight advances in research on the development of MNs-based therapeutics for their implications in hormone delivery. The challenges during clinical translation of MNs from bench to bedside are also discussed.

Microneedle-based insulin transdermal delivery system: current status and translation challenges

Diabetes mellitus is a metabolic disease manifested by hyperglycemia. For patients with type 1 and advanced type 2 diabetes mellitus, insulin therapy is essential. Subcutaneous injection remains the most common administration method. Non-invasive insulin delivery technologies are pursued because of their benefits of decreasing patients' pain, anxiety, and stress. Transdermal delivery systems have gained extensive attention due to the ease of administration and absence of hepatic first-pass metabolism. Microneedle (MN) technology is one of the most promising tactics, which can effectively deliver insulin through skin stratum corneum in a minimally invasive and painless way. This article will review the research progress of MNs in insulin transdermal delivery, including hollow MNs, dissolving MNs, hydrogel MNs, and glucose-responsive MN patches, in which insulin dosage can be strictly controlled. The clinical studies about insulin delivery with MN devices have also been summarized and grouped based on the study phase. There are still several challenges to achieve successful translation of MNs-based insulin therapy. In this review, we also discussed these challenges including safety, efficacy, patient/prescriber acceptability, manufacturing and scale-up, and regulatory authority acceptability.

Comprehensive evaluation of microneedle-based intradermal adalimumab delivery vs. subcutaneous administration: results of a randomized controlled clinical trial

AIMS

To evaluate feasibility of intradermal (i.d.) adalimumab administration using hollow microneedles, and to compare a single i.d. dose of adalimumab using a hollow microneedle with a single subcutaneous (s.c.) dose using a conventional needle.

METHODS

In this single-centre double-blind, placebo-controlled, double-dummy clinical trial in 24 healthy adults we compared 40 mg adalimumab (0.4 mL) administered i.d. using a hollow microneedle with a s.c. dose using a conventional needle. Primary parameters were pain, acceptability and local tolerability; secondary parameters safety, pharmacokinetics and immunogenicity. We explored usability of optical coherence tomography, clinical photography, thermal imaging, and laser speckle contrast imaging to evaluate skin reaction after i.d. injections. In vitro protein analysis was performed to assess compatibility of adalimumab with the hollow microneedle device.

RESULTS

While feasible and safe, injection pain of i.d. adalimumab was higher compared to s.c. adalimumab (35.4 vs. 7.9 on a 100-point visual analogue scale). Initial absorption rate and relative bioavailability were higher after i.d. adalimumab (time to maximum plasma concentration = 95 h [47-120]; Frel = 129% [6.46%]) compared to s.c. adalimumab (time to maximum plasma concentration = 120 h [96-221]). Anti-adalimumab antibodies were detected in 50% and 83% of the subjects after i.d. and s.c. adalimumab, respectively. We observed statistically significantly more erythema and skin perfusion after i.d. adalimumab, compared to s.c. adalimumab and placebo injections (P < .0001). Cytokine secretion after whole blood lipopolysaccharide challenge was comparable between administration routes.

CONCLUSIONS

Intradermal injection of adalimumab using hollowing microneedles was perceived as more painful and less accepted than s.c. administration, but yields a higher relative bioavailability with similar safety and pharmacodynamic effects.

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.

Trends in peptide drug discovery

Since the introduction of insulin almost a century ago, more than 80 peptide drugs have reached the market for a wide range of diseases, including diabetes, cancer, osteoporosis, multiple sclerosis, HIV infection and chronic pain. In this Perspective, we summarize key trends in peptide drug discovery and development, covering the early efforts focused on human hormones, elegant medicinal chemistry and rational design strategies, peptide drugs derived from nature, and major breakthroughs in molecular biology and peptide chemistry that continue to advance the field. We emphasize lessons from earlier approaches that are still relevant today as well as emerging strategies such as integrated venomics and peptide-display libraries that create new avenues for peptide drug discovery. We also discuss the pharmaceutical landscape in which peptide drugs could be particularly valuable and analyse the challenges that need to be addressed for them to reach their full potential.

Using gold nanoparticles for enhanced intradermal delivery of poorly soluble auto-antigenic peptides

Ultra-small 1-2 nm gold nanoparticles (NP) were conjugated with a poorly-soluble peptide auto-antigen, associated with type 1 diabetes, to modify the peptide pharmacokinetics, following its intradermal delivery. Peptide distribution was characterized, in vivo, after delivery using either conventional intradermal injection or a hollow microneedle device. The poorly-soluble peptide was effectively presented in distant lymph nodes (LN), spleen and draining LN when conjugated to the nanoparticles, whereas peptide alone was only presented in the draining LN. By contrast, nanoparticle conjugation to a highly-soluble peptide did not enhance in vivo distribution. Transfer of both free peptide and peptide-NPs from the skin to LN was reduced in mice lacking lymphoid homing receptor CCR7, suggesting that both are actively transported by migrating dendritic cells to LN. Collectively, these data demonstrate that intradermally administered ultra-small gold nanoparticles can widen the distribution of poorly-soluble auto-antigenic peptides to multiple lymphoid organs, thus enhancing their use as potential therapeutics.

Recent advances of nanomedicine-based strategies in diabetes and complications management: Diagnostics, monitoring, and therapeutics

Diabetes mellitus (DM) is a metabolic disorder characterized by the presence of chronic hyperglycemia driven by insulin deficiency or resistance, imposing a significant global burden affecting 463 million people worldwide in 2019. This review has comprehensively summarized the application of nanomedicine with accurate, patient-friendly, real-time properties in the field of diabetes diagnosis and monitoring, and emphatically discussed the unique potential of various nanomedicine carriers (e.g., polymeric nanoparticles, liposomes, micelles, microparticles, microneedles, etc.) in the management of diabetes and complications. Novel delivery systems have been developed with improved pharmacokinetics and pharmacodynamics, excellent drug biodistribution, biocompatibility, and therapeutic efficacy, long-term action safety, as well as the improved production methods. Furthermore, the effective nanomedicine for the treatment of several major diabetic complications with significantly improved life qualities of diabetic patients were discussed in detail. Going through the literature review, several critical issues of the nanomedicine-based strategies applications need to be addressed such as stabilities and long-term safety effects in vivo, the deficiency of standard for formulation administration, feasibility of scale-up, etc. Overall, the review provides an insight into the design, advantages and limitations of novel nanomedicine application in the diagnostics, monitoring, and therapeutics of DM.

The Current Status of Clinical Research Involving Microneedles: A Systematic Review

In recent years, a number of clinical trials have been published on the efficacy and safety of drug delivery using microneedles (MNs). This review aims to systematically summarize and analyze the current evidence including the clinical effect and safety of MNs. Three electronic databases, including PubMed, were used to search the literature for randomized controlled trials (RCTs) and clinical controlled trials (CCTs) that evaluated the therapeutic efficacy of MNs from their inception to 28 June 2018. Data were extracted according to the characteristics of study subjects; disorder, types, and details of the intervention (MNs) and control groups; outcome measurements; effectiveness; and incidence of adverse events (AEs). Overall, 31 RCTs and seven CCTs met the inclusion criteria. Although MNs were commonly used in skin-related studies, evaluating the effects of MNs was difficult because many studies did not provide adequate comparison values between groups. For osteoporosis treatment, vaccine, and insulin delivery studies, MNs were comparable to or more effective than the gold standard. Regarding the safety of MNs, most AEs reported in each study were minor (grade 1 or 2). A well-designed RCT is necessary to clearly evaluate the effectiveness of MNs in the future.

Drug Delivery Systems for Diabetes Treatment

BACKGROUND

Insulin is essential for the treatment of Type 1 diabetes mellitus (T1DM) and is necessary in numerous cases of Type 2 diabetes mellitus (T2DM). Prolonged administration of anti-diabetic therapy is necessary for the maintenance of the normal glucose levels and thereby preventing vascular complications. A better understanding of the disease per se and the technological progress contribute to the development of new approaches with the aim to achieve better glycemic control.

OBJECTIVE

Current therapies for DM are faced with some challenges. The purpose of this review is to analyze in detail the current trends for insulin delivery systems for diabetes treatment.

RESULTS

Contemporary ways have been proposed for the management of both types of diabetes by adequate application of drug via subcutaneous, buccal, oral, ocular, nasal, rectal and pulmonary ways. Development of improved oral administration of insulin is beneficial regarding mimicking physiological pathway of insulin and minimizing the discomfort of the patient. Various nanoparticle carriers for oral and other ways of insulin delivery are currently being developed. Engineered specific properties of nanoparticles (NP): controlling toxicity of NP, stability and drug release, can allow delivery of higher concentration of the drug to the desired location.

CONCLUSIONS

The successful development of any drug delivery system relies on solving three important issues: toxicity of nanoparticles, stability of nanoparticles, and desired drug release rate at targeted sites. The main goals of future investigations are to improve the existing therapies by pharmacokinetic modifications, development of a fully automatized system to mimic insulin delivery by the pancreas and reduce invasiveness during admission.

Randomised clinical trial: a placebo-controlled study of subcutaneous or intradermal NEXVAX2, an investigational immunomodulatory peptide therapy for coeliac disease

BACKGROUND

Nexvax2 contains three gluten-derived peptides, intended to tolerize coeliac disease patients to gluten. Sequences cover six epitopes that trigger immune activation in human leucocyte antigen-DQ2.5-positive patients, most notably after an initial dose. Patients experience gastrointestinal symptoms with increases in serum interleukin-2. Consistent with Nexvax2's induction of non-responsiveness, reactivity disappears after repeated doses, or is avoided with gradual dose escalation. Early clinical trials used intradermal dosing, but pharmacokinetics and rapid onset of effect suggest that subcutaneous delivery may also be effective.

AIMS

To document the relative bioavailability of Nevax2 peptides after subcutaneous and intradermal dosing, and the tolerability and ability of subcutaneous dosing to induce non-responsiveness to Nexvax2 peptides.

METHODS

A randomised, double-blind, placebo-controlled study was conducted to assess plasma pharmacokinetics after subcutaneous and intradermal Nexvax2 dosing in HLA DQ2.5-positive patients, who had symptoms after an oral gluten challenge. Randomisation was to semi-weekly Nexvax2 (n = 12) or placebo (n = 2) injections, over a 5-week subcutaneous dose escalation and 2-week maintenance period, the latter with four doses of 900 µg, two subcutaneous and two intradermal. Post-dose circulating peptide and interleukin-2 levels were assessed. Investigators recorded adverse events experienced by patients.

RESULTS

Subcutaneous dosing resulted in slightly greater exposure. Interleukin-2 responses were seen with the gluten challenge but not after subcutaneous or intradermal dosing of 900 µg. Adverse events were generally mild and self-limited.

CONCLUSIONS

Subcutaneous and intradermal dosing of Nexvax2 yield similar bioavailability of constituent peptides; subcutaneous dose escalation avoids an immune response to dominant gluten epitopes.

Recent advances in microneedle composites for biomedical applications: Advanced drug delivery technologies

In the twenty-first century, microneedles based drug delivery is drawing attention worldwide in the research due to current signs of progress in the controlled release drug delivery through microneedles. The microneedles represent a promising technology to deliver therapeutic compounds into the skin for chronic complications like osteoporosis, diabetes, cancer and induction of immune responses from protein and DNA vaccines. However, the delivery of hydrophilic drugs and macromolecular agents are challenging. In this write up authors included the meticulous illustration of the chronological development of fabrication of microneedles with respect to an assortment of techniques, their modifications, clinical trials and regulatory perspectives period of 2000-2019. This review summarizes characterization, fabrications, biological applications and challenges. Additionally, relevant patents based on microneedle from USPTO) database are also highlighted.

Advances in transdermal insulin delivery

Insulin therapy is necessary to regulate blood glucose levels for people with type 1 diabetes and commonly used in advanced type 2 diabetes. Although subcutaneous insulin administration via hypodermic injection or pump-mediated infusion is the standard route of insulin delivery, it may be associated with pain, needle phobia, and decreased adherence, as well as the risk of infection. Therefore, transdermal insulin delivery has been widely investigated as an attractive alternative to subcutaneous approaches for diabetes management in recent years. Transdermal systems designed to prevent insulin degradation and offer controlled, sustained release of insulin may be desirable for patients and lead to increased adherence and glycemic outcomes. A challenge for transdermal insulin delivery is the inefficient passive insulin absorption through the skin due to the large molecular weight of the protein drug. In this review, we focus on the different transdermal insulin delivery techniques and their respective advantages and limitations, including chemical enhancers-promoted, electrically enhanced, mechanical force-triggered, and microneedle-assisted methods.

Metallic microneedles with interconnected porosity: A scalable platform for biosensing and drug delivery

Metallic-based microneedles (MNs) offer a robust platform for minimally invasive drug delivery and biosensing applications due to their mechanical strength and proven tissue and drug compatibility. However, current designs suffer from limited functional surface area or challenges in manufacturing scalability. Here, porous 316L stainless steel MN patches are proposed. Fabricated through a scalable manufacturing process, they are suitable for storage and delivery of drugs and rapid absorption of fluids for biosensing. Fabrication of these MNs involves hot embossing a patch of stainless steel-based feedstock, sintering at 1100 °C and subsequent electropolishing. Optimisation of this manufacturing process yields devices that maintain mechanical integrity yet possess high surface area and associated porosity (36%) to maximise loading capacity. Similarly, a small pore size has been targeted (average diameter 2.22 μm, with 90% between 1.56 μm and 2.93 μm) to maximise capillarity and loading efficiency. This porous network has a theoretical wicking rate of 4.7 μl/s and can wick-up 27 ± 5 μl of fluid through capillary action which allows for absorption of pharmaceuticals for delivery. When inserted into a metabolite-loaded skin model, the MNs absorbed and recovered 17 ± 3 μl of the metabolite solution. The drug delivery performance of the porous metallic MNs (22.4 ± 4.9 µg/cm²) was found to be threefold higher than that of topical administration (7.1 ± 4.3 µg/cm²). The porous metallic MN patches have been shown to insert into porcine skin under a 19 N load. These results indicate the potential of design-for-manufacturing porous stainless steel MNs in biosensing and drug delivery applications. STATEMENT OF SIGNIFICANCE: Microneedles are micro-scale sharp protrusions used to bypass the stratum corneum, the skin's outer protective layer, and painlessly access dermal layers suitable for drug delivery and biosensing. Despite a depth of research in the area we have not yet seen large-scale clinical adoption of microneedle devices. Here we describe a device designed to address the potential barriers to adoption seen by other microneedles devices. We have developed a scalable, cost effective process to produce medical grade stainless steel microneedle patches which passively absorb and store drugs or interstitial fluid though a porous network and capillary action. This device, with low manufacturing and regulatory burdens may help the large-scale adoption of microneedles.

Preparation, properties and challenges of the microneedles-based insulin delivery system

Microneedle technology relates to pharmacy, polymer chemistry and micromachining. Microneedle can effectively deliver insulin into systemic circulation across the skin. This process does not affect the activity of insulin. Compared to subcutaneous injection, microneedles cause less pain for their special structure. This review thoroughly discusses the preparation technologies of the microneedles-based insulin delivery system including solid, hollow, dissolving, phase transition, glucose-responsive microneedle patches. In the meantime, the properties, challenges and clinical/commercial status of the microneedles-based insulin delivery system are also discussed in this review.

Insulin delivery systems combined with microneedle technology

Diabetes, a metabolic disorder of glucose, is a serious chronic disease and an important public health problem. Insulin is one of the hormones for modulating blood glucose level and the products of which is indispensable for most diabetes patients. Introducing microneedles (MNs) to insulin delivery is promising to pave the way for modulating glucose level noninvasively of diabetes patients, as which born to be painless, easy to handle and no need of any power supply. In this work, we review the process of insulin delivery systems (IDSs) based on MN technology in terms of two categories: drug free MNs and drug loaded MNs. Drug free MNs include solid MNs ("poke and patch"), hollow MNs ("poke and flow") and reservoir-based swelling MNs ("poke and swell R-type"), and drug loaded MNs include coated MNs ("coat and poke"), dissolving MNs ("poke and release") and insulin incorporated swelling MNs ("poke and swell I-type"). Majority researches of MN-based IDSs have been conducted by using hollow MNs or dissolving MNs, and almost all clinical trials for MN-based IDSs have employed hollow MNs. "Poke and patch" approach dramatically increase skin permeability compared to traditional transdermal patch, but MNs fabricated from silicon or metal may leave sharp waste in the skin and cause a safety issue. "Poke and flow" approach, similar to transitional subcutaneous (SC) injection, is capable of producing faster insulin absorption and action than SC injection but may associate with blockage, leakage and low flow rate. Coated MNs are able of retaining the activity of drug, which loaded in a solid phase, for a long time, however have been relatively less studied for insulin application as the low drug dosing. "Poke and release" approach leaves no biohazardous sharp medical waste and is capable of rapid drug release. "Poke and swell R-type" can be seen as a combination of "poke and flow" and "poke and patch" approach, while "poke and swell I-type" is an approach between "coat and poke" and "poke and release" approach. Insulin MNs are promising for painless diabetes therapeutics, and additional efforts for addressing fundamental issues including the drug loading, the PK/PD profile, the storage and the safety of insulin MNs will accelerate the clinical transformation.

Human studies with microneedles for evaluation of their efficacy and safety

INTRODUCTION

During the past two decades, many studies have documented the development of microneedles (MNs) as a feasible technique for the effective administration of drugs. More and more human studies have been done with MNs to bridge the gap between research and market applications that provide efficacious techniques for clinical implementation.

AREAS COVERED

The aim of this review is provide a brief description of the status of human study with MNs and to demonstrate progress for the right use of microneedle arrays in clinical settings. It also describes the considerations for clinical application with each type of MNs.

EXPERT OPINION

Microneedle systems were introduced to overcome the limitations of conventional methods of drug administration. Lots of microneedle systems have undergone clinical evaluation to determine their efficacy and safety, and many studies have demonstrated positive results. The successful clinical use of the microneedle in vaccine therapy is remarkable and supports the importance of conducting further tests in a wide range of medical applications. Self-administered MNs appeared to be an attractive alternative method that needs further research to become a reality in the near future.

Insulin (Technique) Induced Hypoglycaemia

The most common side effect of insulin therapy is hypoglycaemia apart from weight gain. It occurs commonly due to insulin overdose, faulty injection site, technique and meal-insulin mismatch. In lean individuals even the needle size can be a contributing factor to hypoglycaemia. Here we report a case who presented with recurrent episodes of hypoglycaemia due to a combination of wrong insulin site, technique as well as needle size. On examination, he was found to have spotted dermopathy on his forearms (insulin injection site) which was consistent with intradermal insulin administration. Recently, insulin infusion through intradermal route has been found to reach the systemic circulation faster than even the conventional subcutaneous injection. This case emphasizes that hypoglycaemias can occur due to less common causes. It warrants a good clinical examination and patient education.