Iontophoretic drug delivery

Recent updates on drug delivery approaches for improved ocular delivery with an insight into nanostructured drug delivery carriers for anterior and posterior segment disorders

Ocular diseases have a major impact on patient's vision and quality of life, with approximately 2.2 billion people have visual impairment worldwide according to the findings from the World Health Organization (WHO). The eye is a complex organ with unique morphology and physiology consisting of numerous ocular barriers which hinders the entry of exogenous substances and impedes drug absorption. This in turn has a substantial impact on effective drug delivery to treat ocular diseases, especially intraocular disorders which has consistently presented a challenge to eye care professionals. The most common method of delivering medications to the eye is topical instillation of eye drops. Although this approach is a viable option for treating many ocular diseases remains a major challenge for the effective treatment of posterior ocular conditions. Up till now, incessant efforts have been committed to design innovative drug delivery systems with the hopes of potential clinical application. Modern developments in nanocarrier's technology present a potential chance to overcome these obstacles by enabling targeted delivery of the loaded medication to the eyes with improved solubility, delayed release, higher penetration and increased retention. This review covers the anatomy of eye with associated ocular barriers, ocular diseases and administration routes. In addition it primarily focuses on the latest progress and contemporary applications of ophthalmic formulations providing specific insight on nanostructured drug delivery carriers reported over the past 5 years highlighting their values in achieving efficient ocular drug delivery to both anterior and posterior segments. Most importantly, we outlined in this review the macro and nanotechnology based ophthalmic drug formulations that are being patented or marketed so far for treating ocular diseases. Finally, based on current trends and therapeutic concepts, we highlighted the challenges faced by novel ocular drug delivery systems and provided prospective future developments for further research in these directions. We hope that this review will serve as a source of motivation and ideas for formulation scientists in improving the design of innovative ophthalmic formulations.

Iontophoresis and electroporation-assisted microneedles: advancements and therapeutic potentials in transdermal drug delivery

Transdermal drug delivery (TDD) using electrically assisted microneedle (MN) systems has emerged as a promising alternative to traditional drug administration routes. This review explores recent advancements in this technology across various therapeutic applications. Integrating iontophoresis (IP) and electroporation (EP) with MN technology has shown significant potential in improving treatment outcomes for various conditions. Studies demonstrate their effectiveness in enhancing vaccine and DNA delivery, improving diabetes management, and increasing efficacy in dermatological applications. The technology has also exhibited promise in delivering nonsteroidal anti-inflammatory drugs (NSAIDs), treating multiple sclerosis, and advancing obesity and cancer therapy. These systems offer improved drug permeation, targeted delivery, and enhanced therapeutic effects. While challenges remain, including safety concerns and technological limitations, ongoing research focuses on optimizing these systems for broader clinical applications. The future of electrically assisted MN technologies in TDD appears promising, with potential advancements in personalized medicine, smart monitoring systems, and expanded therapeutic applications.

Ocular drug delivery systems based on nanotechnology: a comprehensive review for the treatment of eye diseases

Ocular drug delivery is a significant challenge due to the intricate anatomy of the eye and the various physiological barriers. Conventional therapeutic approaches, while effective to some extent, often fall short in effectively targeting ocular diseases, resulting in suboptimal therapeutic outcomes due to factors such as poor ocular bioavailability, frequent dosing requirements, systemic side effects, and limited penetration through ocular barriers. This review elucidates the eye's intricate anatomy and physiology, prevalent ocular diseases, traditional therapeutic modalities, and the inherent pharmacokinetic and pharmacodynamic limitations associated with these modalities. Subsequently, it delves into nanotechnology-based solutions, presenting breakthroughs in nanoformulations such as nanocrystals, liposomes, dendrimers, and nanoemulsions that have demonstrated enhanced drug stability, controlled release, and deeper ocular penetration. Additionally, it explores a range of nanosized carriers, including nano-structured lipid carriers, hydrogels, nanogels, nanoenzymes, microparticles, conjugates, exosomes, nanosuspensions, viral vectors, and polymeric nanoparticles, and their applications. Unique insights include emerging innovations such as nanowafers and transcorneal iontophoresis, which indicate paradigm shifts in non-invasive ocular drug delivery. Furthermore, it sheds light on the advantages and limitations of these nanotechnology-based platforms in addressing the challenges of ocular drug delivery. Though nano-based drug delivery systems are drawing increasing attention due to their potential to enhance bioavailability and therapeutic efficacy, the review ends up emphasizing the imperative need for further research to drive innovation and improve patient outcomes in ophthalmology.

Ionic conducting hydrogels as biomedical materials: classification, design strategies, and skin tissue engineering applications

Ionically conductive hydrogels (ICHs) are considered promising flexible electronic devices and various wearable sensors due to the integration of the conductive performance and soft nature of human tissue-like materials with mechanical and sensory traits. Recently, substantial progress has been made in the research of ICHs, including high conductivity, solution processability, strong adhesion, high stretchability, high self-healing ability, and good biocompatibility. These advanced researches also promote their excellent application prospects in medical monitoring, sports health, smart wear, and other fields. This article reviewed ICHs' current classification and design strategies in biomedical applications and the structure-activity relationship of the interface between biological systems and electronics. Furthermore, the typical cases of frontiers of skin interface applications of ICHs were elaborated in transdermal drug delivery, wound healing, disease diagnosis and treatment, and human-computer interaction. This article aims to inspire related research on ionically conductive hydrogels in the biomedical field and promote the innovation and application of flexible wearable electronic device technology.

Recent advances in cutaneous drug delivery by iontophoresis

INTRODUCTION

Iontophoresis has been extensively studied for topical and transdermal drug delivery to stimulate the absorption of molecules that would hardly pass through the outermost layer of the skin passively. Recent research has focused on its combination with nanoparticle-based systems or microneedles to expand its therapeutic applications.

AREAS COVERED

This review explores the fundamental principles of iontophoresis, focusing on key factors influencing its drug transport mechanisms, and provides a discussion of the field's current state. A comprehensive analysis of articles published or available online in 2024 was conducted, categorizing studies by their application areas, drug delivery systems, iontophoretic conditions, and experimental limitations.

EXPERT OPINION

The findings reveal a recent focus on wound healing and skin repair, and advancements in treating inflammation, pain, and skin cancer. Market translation requires standardized experimental protocols, particularly for iontophoretic parameters and preclinical models, along with the development of cost-effective commercial devices. Additionally, while advancements in cutaneous drug delivery have increasingly benefited from machine learning approaches, their application to iontophoresis remains underexplored. With the growing interest in associating iontophoresis with the Internet of Things, such an integration, if combined with AI tools, could offer promising opportunities for personalized, real-time treatments in modern dermatology, and therapeutic systems.

Flexible surface acoustic wave technology for enhancing transdermal drug delivery

Transdermal drug delivery provides therapeutic benefits over enteric or injection delivery because its transdermal routes provide more consistent concentrations of drug and avoid issues of drugs affecting kidneys and liver functions. Many technologies have been evaluated to enhance drug delivery through the relatively impervious epidermal layer of the skin. However, precise delivery of large hydrophilic molecules is still a great challenge even though microneedles or other energized (such as electrical, thermal, or ultrasonic) patches have been used, which are often difficult to be integrated into small wearable devices. This study developed a flexible surface acoustic wave (SAW) patch platform to facilitate transdermal delivery of macromolecules with fluorescein isothiocyanates up to 2000 kDa. Two surrogates of human skin were used to evaluate SAW based energized devices, i.e., delivering dextran through agarose gels and across stratum corneum of pig skin into the epidermis. Results showed that the 2000 kDa fluorescent molecules have been delivered up to 1.1 mm in agarose gel, and the fluorescent molecules from 4 to 2000 kDa have been delivered up to 100 µm and 25 µm in porcine skin tissue, respectively. Mechanical agitation, localised streaming, and acousto-thermal effect generated on the skin surface were identified as the main mechanisms for promoting drug transdermal transportation, although micro/nanoscale acoustic cavitation induced by SAWs could also have its contribution. SAW enhanced transdermal drug delivery is dependent on the combined effects of wave frequency and intensity, duration of applied acoustic waves, temperature, and drug molecules molecular weights.

Tailoring Design of Microneedles for Drug Delivery and Biosensing

Microneedles (MNs) are emerging as versatile tools for both therapeutic drug delivery and diagnostic monitoring. Unlike hypodermic needles, MNs achieve these applications with minimal or no pain and customizable designs, making them suitable for personalized medicine. Understanding the key design parameters and the challenges during contact with biofluids is crucial to optimizing their use across applications. This review summarizes the current fabrication techniques and design considerations tailored to meet the distinct requirements for drug delivery and biosensing applications. We further underscore the current state of theranostic MNs that integrate drug delivery and biosensing and propose future directions for advancing MNs toward clinical use.

Investigating iontophoresis as a therapeutic approach for Peyronie's disease: a systematic review

INTRODUCTION

Iontophoresis therapy (IPT) is a noninvasive technique that uses electrical impulses to deliver charged molecules into the skin for controlled and targeted drug delivery. IPT has been explored as a noninvasive treatment option for Peyronie's disease (PD), but the current literature in this regard is still scarce.

OBJECTIVE

We aimed to systematically review the current literature on the application of IPT in the management of PD to provide a comprehensive evaluation and holistic outlook on the subject.

METHOD

A comprehensive search strategy was implemented in the following databases to retrieve research articles: PubMed (MEDLINE), Scopus, and Web of Science. Google Scholar was also manually searched. The search results were imported into Rayyan reference management for assessment based on the predefined inclusion criteria. The quality of the articles was evaluated by the proper JBI checklist (ie, per the study design), and the JBI grades of recommendation were used for grading the evidence.

RESULTS

A systematic search yielded 451 publications, 11 of which met the criteria to be included in this systematic review. The results demonstrated that IPT, usually with verapamil and dexamethasone, has shown promising results in treating PD. These methods can reduce pain, plaque size, and penile curvature while improving sexual function and quality of life with no serious adverse events. However, most studies had moderate to low quality, indicating a weak recommendation for a certain health management strategy.

CONCLUSION

Based on the extant literature, there is currently insufficient evidence to support the use of IPT for the management of PD. Placing it in the forefront of research can facilitate the management choices for PD even further, given its therapeutic potential.

Intracorneal iontophoretic delivery of triamcinolone acetonide prodrugs: Physicochemical parameters guiding electrotransport

Intracorneal delivery of ten amino acid (alanine, arginine, asparagine, glutamine, glycine, histidine, isoleucine, lysine, methionine and valine) ester prodrugs of triamcinolone acetonide (TA-AA) was investigated in vitro, using a corneal iontophoresis device (IONTOFOR-CXL; SOOFT Italia S.p.A.) approved for clinical use in the treatment of keratoconus. Short duration iontophoresis (1 mA for 5 min) was performed and intracorneal deposition of TA was quantified by HPLC-UV and UHPLC-MS/MS. The data evidenced the clear advantage of TA-AA prodrug iontophoresis compared to passive delivery and revealed unexpected and prodrug dependent deposition profiles. Despite their superior electrical mobility, intracorneal delivery of dications, TA-Arg and TA-Lys, did not outperform that of TA-Ala and TA-Gly. In silico investigations to relate the TA-AA prodrugs' physicochemical properties to their electrotransport confirmed that increased lipophilicity potential did not favour iontophoretic transport. For TA-Ala and TA-Gly, it was hypothesized that the greater charge distribution and decreased tendency to interact with the corneal tissue via electrostatic and H-bonds contributed to their successful iontophoretic delivery. Intracorneal biodistribution of TA confirmed that TA-Gly iontophoresis resulted in supratherapeutic concentrations in deep corneal stroma, exceeding TA IC50 by ∼ 104-fold. The results clearly demonstrated the successful combination of the clinically approved SOOFT iontophoretic device and the TA-AA prodrugs for targeted corneal iontophoretic delivery.

Strategies for transportation of peptides across the skin for treatment of multiple diseases

An established view in genetic engineering dictates an increase in the discovery of therapeutic peptides to enable the treatment of multiple diseases. The use of hypodermic needle for delivery of proteins and peptides occurs due to the hydrophilic nature, sensitivity toward proteolytic enzymes and high molecular weight. The non-invasive nature of the transdermal delivery technique offers multiple advantages over the invasive route to release drugs directly into the systemic circulation to enhance bioavailability, better patient compliance, reduced toxicity and local irritability. The transdermal route seems highly desirable from the pharmaco-therapeutic and patient compliance point of view, however, the lipophilic barrier of skin restricts the application. The use of several techniques like electrical methods (iontophoresis, sonophoresis etc.), chemical penetration enhancers (e.g. protease inhibitors, penetration enhancers, etc.) and nanocarriers (dendrimers, lipid nanocapsules, etc.) are utilized to improve the passage of drug molecules across the biomembranes. Additionally, such clinical interventions facilitate the physicochemical characteristics of peptides, to enable effective preservation, conveyance and release of therapeutic agents. Moreover, strategies ensure the attainment of the intended targets and enhance treatment outcomes for multiple diseases. This review article focuses on the techniques of peptide transportation across the skin to advance the delivery approaches and therapeutic efficiency.

Effect of gelatin nanoparticles' size and charge on iontophoretic targeted deposition to the hair follicles

Hair follicles (HFs) represent a route of interest to drug delivery for treating several skin conditions. Iontophoresis, on the other hand, is a physical method to enhance drug permeation by applying a low electrical current to the formulation. HFs can be targeted following topical iontophoretic application, as they represent a pathway of lower electrical resistance, as well as a drug reservoir, in particular useful for nanoparticles (NPs), which can preferably accumulate in these structures. Combining both strategies may provide optimal results, but the literature still lacks evidence of the ideal NP characteristics for the iontophoretic drug delivery targeting the HFs. Here, we aimed to evaluate the effect of gelatin NPs' size and charge under iontophoresis application on NPs' deposition into the HFs. Four gelatin NP formulations were produced with varying gelatin concentrations and gelatin types (positively charged type A and negatively charged type B), with sizes ranging from 220 to 770 nm. A fluorescent dye, TRITC-dextran 150 kDa, was encapsulated for monitoring NPs deposition. Cutaneous penetration experiments were performed in vitro with and without iontophoresis for 6 h with pig ear skin. The deposition profile was assessed by confocal laser scanning microscopy. Photomicrographs showed a higher accumulation of the larger positively charged NPs (AL), reaching deeper portions of HFs, and showed iontophoresis further increased their deposition, resulting in the highest signal. In conclusion, these findings shed light on the applications of NPs and bring novel treatment opportunities for several diseases compromising the hair follicles.

Effect of low-frequency acupuncture on muscle and fascia stiffness: examination with or without intervention

Background

Low-frequency acupuncture is used to maintain skeletal muscle flexibility and improve joint range of motion; however, its definite effects are unclear. This study aimed to determine the effects of low-frequency acupuncture on muscle and fascial stiffness and ankle dorsiflexion range of motion.

Methods

The participants included 12 randomly selected healthy adults. The medial head of the gastrocnemius muscle was selected as the target muscle, and changes in hardness and dorsiflexion range of motion of the ankle joint in the deep fascia, muscle, and deep intermuscular fascia of the same region were measured before and after low-frequency acupuncture intervention. Acupuncture needles were inserted until they passed through the deep intermuscular fascia and electrically stimulated at a frequency of 2 Hz for 15 min. The 12 right legs were the intervention legs, and the 12 left legs were the non-intervention legs.

Results

In the intervention leg, hardness increased in the deep fascia immediately after low-frequency acupuncture, but decreased in all regions (deep fascia, muscle, and deep intermuscular fascia) after 15 min. The rate of change in hardness was the greatest in the muscles and deep intermuscular fascia. Additionally, the ankle's dorsiflexion range of motion increased after 15 min. In contrast, the non-intervention leg showed no significant changes in stiffness or ankle dorsiflexion angle.

Conclusions

Low-frequency acupuncture may decrease muscle stiffness and improve fascial gliding. The change in hardness tended to be greater in the deeper areas.

Electrostimulation: A Promising New Treatment for Psoriasis

Psoriasis is a chronic inflammatory skin disease caused by abnormal activation and immune system disorder. Despite the availability of several treatments, they only provide temporary relief, and there is a critical need for more effective therapies to manage this condition. Electrostimulation has been widely used as a physical stimulus in treating various diseases, and recent studies have shown its potential in psoriasis treatment. In this review, we explore the direct and indirect effects of electrostimulation in treating psoriasis and their underlying mechanisms (the decreased secretion of inflammatory cytokines, the loss of cell-to-cell connections, and the cAMP signaling pathway). Our findings suggest that electrostimulation therapy may offer a promising approach to treating psoriasis and developing wearable devices for its management.

Effect of iontophoresis on dacarbazine cutaneous delivery for melanoma topical treatment

Dacarbazine (DTIC) is the drug of choice for melanoma treatment, but its systemic administration is related to several adverse effects. Here, DTIC topical delivery stimulated by iontophoresis is proposed to overcome such drawbacks. Hence, this work analyzed the impact of anodal iontophoresis on DTIC cutaneous delivery to provide an innovative topical alternative for melanoma treatment. The electrical stability of the drug was evaluated prior to the iontophoretic experiments, which demonstrated the need to add an antioxidant to the drug formulation. DTIC cutaneous permeation was evaluated in vitro for 6 h using three current densities (0.10, 0.25, and 0.50 mA/cm2). In addition, the effect of DTIC against skin cancer cells (MeWo and WM164) was investigated for 72 h of exposure to the drug. Iontophoresis stimulated skin drug permeation compared to the passive control. However, the antioxidant presence reduced DTIC permeation under the lower currents of 0.10 and 0.25 mA/cm2, which was compensated by increasing the current density to 0.50 mA/cm2. At 0.50 mA/cm2, iontophoresis enhanced topical cutaneous drug permeation 7-fold (p < 0.05) compared to the passive control. DTIC showed a concentration-dependent antiproliferative effect on melanoma cell lines. Thus, iontophoresis intensifies DTIC skin penetration in concentrations that can reduce cell viability and induce cell death. In conclusion, DTIC cutaneous delivery mediated by iontophoresis is a promising approach for treating melanomas and other skin tumors.

Penetration enhancers strengthen tough hydrogel bioadhesion and modulate locoregional drug delivery

The human body possesses natural barriers, such as skin and mucosa, which limit the effective delivery of therapeutics and integration of medical devices to target tissues. Various strategies have been deployed to breach these barriers mechanically, chemically, or electronically. The development of various penetration enhancers (PEs) offers a promising solution due to their ability to increase tissue permeability using readily available reagents. However, existing PE-mediated delivery methods often rely on weak gel or liquid drug formulations, which are not ideal for sustained local delivery. Hydrogel adhesives that can seamlessly interface biological tissues with controlled drug delivery could potentially resolve these issues. Here, we demonstrate that tough adhesion between drug-laden hydrogels and biological tissue (e.g. skin and tumours) can lead to effective local delivery of drugs deep into targeted tissues by leveraging the enhanced tissue penetration mediated by PEs. The drug release profile of the hydrogel adhesives can be fine-tuned by further engineering the nanocomposite hydrogel matrix to elute chemotherapeutics from 2 weeks to 2 months. Using a 3D tumour spheroid model, we demonstrated that PEs increased the cancer-killing effectiveness of doxorubicin by facilitating its delivery into tumour microtissues. Therefore, the proposed tough bioadhesion and drug delivery strategy modulated by PEs holds promise as a platform technique to develop next-generation wearable and implantable devices for cancer management and regenerative medicine.

Pretreatment of microneedles enhances passive transdermal administration of pilocarpine and pilocarpine-induced sweat production in humans

The development of an effective transdermal drug delivery protocol to eccrine sweat glands is important for the advancement of research on the human sweating response. We investigated whether microneedle treatment prior to the application of pilocarpine, a hydrophilic and sudorific agent that does not induce sweating due to a limited percutaneous passive diffusion by skin application alone, augments sweat production. We applied three microneedle arrays to forearm skin sites simultaneously (n = 20). Upon removal of the microneedles, 1 % pilocarpine was applied to each site for 5-, 15-, and 30-min for the assessment of sweat gland function. In parallel, pilocarpine was administered by transdermal iontophoresis (5-min) at a separate site. Sweat rate was assessed continuously via the ventilated capsule technique. Pilocarpine augmented sweat rate at the 15- and 30-min periods as compared to the application at 5-min. The sweating responses induced by the 15- and 30-min application of pilocarpine were equivalent to ∼ 80 % of that measured at the iontophoretically treated sites. Notably, we observed a correlation in sweat rate between these two transdermal drug delivery methods. Altogether, our findings show that pre-treatment of microneedle arrays can enhance transdermal delivery efficiency of pilocarpine to human eccrine sweat glands.

Soft and Flexible Bioelectronic Micro-Systems for Electronically Controlled Drug Delivery

The concept of targeted and controlled drug delivery, which directs treatment to precise anatomical sites, offers benefits such as fewer side effects, reduced toxicity, optimized dosages, and quicker responses. However, challenges remain to engineer dependable systems and materials that can modulate host tissue interactions and overcome biological barriers. To stay aligned with advancements in healthcare and precision medicine, novel approaches and materials are imperative to improve effectiveness, biocompatibility, and tissue compliance. Electronically controlled drug delivery (ECDD) has recently emerged as a promising approach to calibrated drug delivery with spatial and temporal precision. This article covers recent breakthroughs in soft, flexible, and adaptable bioelectronic micro-systems designed for ECDD. It overviews the most widely reported operational modes, materials engineering strategies, electronic interfaces, and characterization techniques associated with ECDD systems. Further, it delves into the pivotal applications of ECDD in wearable, ingestible, and implantable medical devices. Finally, the discourse extends to future prospects and challenges for ECDD.

Breaking barriers: Innovative approaches for skin delivery of RNA therapeutics

RNA therapeutics represent a rapidly expanding platform with game-changing prospects in personalized medicine. The disruptive potential of this technology will overhaul the standard of care with reference to both primary and specialty care. To date, RNA therapeutics have mostly been delivered parenterally via injection, but topical administration followed by intradermal or transdermal delivery represents an attractive method that is convenient to patients and minimally invasive. The skin barrier, particularly the lipid-rich stratum corneum, presents a significant hurdle to the uptake of large, charged oligonucleotide drugs. Therapeutic oligonucleotides need to be engineered for stability and specificity and formulated with state-of-the-art delivery strategies for efficient uptake. This review will cover various passive and active strategies deployed to enhance permeation through the stratum corneum and achieve effective delivery of RNA therapeutics to treat both local skin disorders and systemic diseases. Some strategies to achieve selectivity between local and systemic administration will also be discussed.

Progress and Challenges of Topical Delivery Technologies Meditated Drug Therapy for Osteoarthritis

Osteoarthritis (OA) is a degenerative disease commonly seen in middle-aged and elderly people. Multiple cytokines are involved in the local tissue damage in OA. Currently, non-pharmacologic and surgical interventions are the main conventional approaches for the treatment of OA. In terms of pharmaceutical drug therapy, NSAIDs and acetaminophen are mainly used to treat OA. However, it is prone to various adverse reactions such as digestive tract ulcer, thromboembolism, prosthesis loosening, nerve injury and so on. With the in-depth study of OA, more and more novel topical drug delivery strategies and vehicles have been developed, which can make up for the shortcomings of traditional dosage forms, improve the bioavailability of drugs, and significantly reduce drug side effects. This review summarizes the immunopathogenesis, treatment guidelines, and progress and challenges of topical delivery technologies of OA, with some perspectives on the future pharmacological treatment of OA proposed.

Strategies to Improve the Transdermal Delivery of Poorly Water-Soluble Non-Steroidal Anti-Inflammatory Drugs

The transdermal delivery of non-steroidal anti-inflammatory drugs (NSAIDs) has the potential to overcome some of the major disadvantages relating to oral NSAID usage, such as gastrointestinal adverse events and compliance. However, the poor solubility of many of the newer NSAIDs creates challenges in incorporating the drugs into formulations suitable for application to skin and may limit transdermal permeation, particularly if the goal is therapeutic systemic drug concentrations. This review is an overview of the various strategies used to increase the solubility of poorly soluble NSAIDs and enhance their permeation through skin, such as the modification of the vehicle, the modification of or bypassing the barrier function of the skin, and using advanced nano-sized formulations. Furthermore, the simple yet highly versatile microemulsion system has been found to be a cost-effective and highly successful technology to deliver poorly water-soluble NSAIDs.

Designing of a new transdermal antibiotic delivery polymeric membrane modified by functionalized SBA-15 mesoporous filler

A new drug delivery system using an asymmetric polyethersulfone (PES) membrane modified by SBA-15 and glutamine-modified SBA-15 (SBA-Q) was prepared in this study by the aim of azithromycin delivery enhancement in both in vitro and ex vivo experiments. The research focused on optimizing membrane performance by adjusting critical parameters including drug concentration, membrane thickness, modifier percentage, polymer percentage, and pore maker percentage. To characterize the fabricated membranes, various techniques were employed, including scanning electron microscopy, water contact angle, and tensile strength assessments. Following optimization, membrane composition of 17% PES, 2% polyvinylpyrrolidone, 1% SBA-15, and 0.5% SBA-Q emerged as the most effective. The optimized membranes demonstrated a substantial increase in drug release (906 mg/L) compared to the unmodified membrane (440 mg/L). The unique membrane structure, with a dense top layer facilitating sustained drug release and a porous sub-layer acting as a drug reservoir, contributed to this improvement. Biocompatibility assessments, antibacterial activity analysis, blood compatibility tests, and post-diffusion tissue integrity evaluations confirmed the promising biocompatibility of the optimized membranes. Moreover, long-term performance evaluations involving ten repeated usages underscored the reusability of the optimized membrane, highlighting its potential for sustained and reliable drug delivery applications.

Transdermal drug delivery mediated by acoustic vortex beam

Ultrasound-mediated transdermal drug delivery exhibits various advantages such as biocompatibility, controllability and safety, which attracts plenty of interests within biomedical field. Current researches mostly emphasizes the acoustic cavitation generated by planar or focused waves while neglecting other physics that occur during transportation. Our experimental study illustrates the presence of an acoustic vortex (AV) beam that exhibits a lower acoustic intensity and typically means a lower dose of inertial cavitation, yet achieves a more efficient delivery. Such a result calls for the fundamental mechanism of ultrasound-mediated transdermal transfer using the AV beam. In this work, according to our knowledge, the AV beam is firstly introduced to ultrasound-mediated transdermal medication delivery. The transversal acoustic radiation force (T-ARF), which is the primary characteristic carried by the acoustic vortex beam, and its contribution to the transport enhancement are investigated. It is shown that a focused AV (FAV) beam with a maximal acoustic pressure of 200 kPa induces a pN-level T-ARF, which promotes the enlargement of pores on the stratum corneum and thereby enhances the permeability, as compared with a zero-order (non-vortex) counterpart. This contribution of the T-ARF is validated by the experimental transport on the cellulose membrane, which exhibits a significantly increased membrane porosity and delivery efficiency. The favorable results introduce the new degree of freedom into the ultrasound-mediated transdermal drug transport based on AV beam, and thereby promotes the development of a combined control strategy for more precise and efficient transdermal drug delivery in conjunction with the administration of acoustic cavitation.

Biomedical applications of stimuli-responsive "smart" interpenetrating polymer network hydrogels

In recent years, owing to the ongoing advancements in polymer materials, hydrogels have found increasing applications in the biomedical domain, notably in the realm of stimuli-responsive "smart" hydrogels. Nonetheless, conventional single-network stimuli-responsive "smart" hydrogels frequently exhibit deficiencies, including low mechanical strength, limited biocompatibility, and extended response times. In response, researchers have addressed these challenges by introducing a second network to create stimuli-responsive "smart" Interpenetrating Polymer Network (IPN) hydrogels. The mechanical strength of the material can be significantly improved due to the topological entanglement and physical interactions within the interpenetrating structure. Simultaneously, combining different network structures enhances the biocompatibility and stimulus responsiveness of the gel, endowing it with unique properties such as cell adhesion, conductivity, hemostasis/antioxidation, and color-changing capabilities. This article primarily aims to elucidate the stimulus-inducing factors in stimuli-responsive "smart" IPN hydrogels, the impact of the gels on cell behaviors and their biomedical application range. Additionally, we also offer an in-depth exposition of their categorization, mechanisms, performance characteristics, and related aspects. This review furnishes a comprehensive assessment and outlook for the advancement of stimuli-responsive "smart" IPN hydrogels within the biomedical arena. We believe that, as the biomedical field increasingly demands novel materials featuring improved mechanical properties, robust biocompatibility, and heightened stimulus responsiveness, stimuli-responsive "smart" IPN hydrogels will hold substantial promise for wide-ranging applications in this domain.

Advancements in Skin-Mediated Drug Delivery: Mechanisms, Techniques, and Applications

Skin-mediated drug delivery methods currently are receiving significant attention as a promising approach for the enhanced delivery of drugs through the skin. Skin-mediated drug delivery offers the potential to overcome the limitations of traditional drug delivery methods, including oral administration and intravenous injection. The challenges associated with drug permeation through layers of skin, which act as a major barrier, are explored, and strategies to overcome these limitations are discussed in detail. This review categorizes skin-mediated drug delivery methods based on the means of increasing drug permeation, and it provides a comprehensive overview of the mechanisms and techniques associated with these methods. In addition, recent advancements in the application of skin-mediated drug delivery are presented. The review also outlines the limitations of ongoing research and suggests future perspectives of studies regarding the skin-mediated delivery of drugs.

Novel Discoveries and Clinical Advancements for Treating Onychomycosis: A Mechanistic Insight

Onychomycosis continues to be the most challenging disease condition for pharmaceutical scientists to develop an effective drug delivery system. Treatment challenges lie in incomplete cure and high relapse rate. Present compilation provides cumulative information on pathophysiology, diagnostic techniques, and conventional treatment strategies to manage onychomycosis. Novel technologies developed for successful delivery of antifungal molecules are also discussed in brief. Multidirectional information offered by this article also unlocks the panoramic view of leading patented technologies and clinical trials. The obtained clinical landscape recommends the use of advanced technology driven approaches, as a promising way-out for treatment of onychomycosis. Collectively, present review warrants the application of novel technologies for the successful management of onychomycosis. This review will assist readers to envision a better understanding about the technologies available for combating onychomycosis. We also trust that these contributions address and certainly will encourage the design and development of nanocarriers-based delivery vehicles for effective management of onychomycosis.

Iontophoresis use for increasing drug penetration into root canals and dentinal tubules: A proof-of-concept study

INTRODUCTION

The success of endodontic treatment depends on the significant disinfection of the root canal system, its irregularities, and dentinal tubules. However, achieving complete disinfection remains challenging, with frequent failures and occurrence of secondary infections. Here, we propose using iontophoresis to increase the penetration and distribution of disinfecting agents into root canals, using methylene blue for proof-of-concept.

METHODS

The marker was applied in bovine root canals, and the radial distribution of the dye in the dentinal tubules was evaluated by optical microscopy. Iontophoresis was applied at 0.5 and 1.5 mA for 5 and 15 min.

RESULTS

A significant statistical difference (p < 0.05) was observed in the marker penetration between passive and iontophoretic applications. Both current density and application time had an important effect on methylene blue distribution, with a greater efficacy delivery to the apical region achieved after 1.5 mA for 5 min or 0.5 mA for 15 min, showing longer application time can compensate for lower application current.

CONCLUSION

Iontophoresis increases the penetration and distribution of methylene blue into bovine root canals and dentinal tubules, including its innermost portions.

CLINICAL SIGNIFICANCE

Iontophoresis has shown to be a promising technique for root canal and dentinal tubule disinfection.

Advanced Formulation Approaches for Proteins

Proteins and peptides are highly desirable as therapeutic agents, being highly potent and specific. However, there are myriad challenges with processing them into patient-friendly formulations: they are often unstable and have a tendency to aggregate or degrade upon storage. As a result, the vast majority of protein actives are delivered parenterally as solutions, which has a number of disadvantages in terms of cost, accessibility, and patient experience. Much work has been undertaken to develop new delivery systems for biologics, but to date this has led to relatively few products on the market. In this chapter, we review the challenges faced when developing biologic formulations, discuss the technologies that have been explored to try to overcome these, and consider the different delivery routes that can be applied. We further present an overview of the currently marketed products and assess the likely direction of travel in the next decade.

Development of an Effective Psoriasis Treatment by Combining Tacrolimus-Encapsulated Liposomes and Iontophoresis

Psoriasis is a chronic T-cell-mediated autoimmune skin disease. Tacrolimus (FK506) is commonly used treatment for psoriasis. However, since the molecular weight of FK506 is more than 500 Da, its skin penetration is limited, so that there is a need to improve the penetrability of FK506 to allow for more effective treatment. To this end, we employed iontophoresis (ItP), which is a physical, intradermal drug delivery technology that relies on the use of weak electric current. Previous findings suggest that activation of cell signaling by the weak electric current applied during ItP may affect the expression of inflammatory cytokines, leading to aggravation of psoriasis. In this study, we analyzed the effect of ItP on the expression of various inflammatory cytokines in the skin, and subsequently examined the therapeutic effect of ItP using negatively-charged liposomes encapsulating FK506 (FK-Lipo) in a rat psoriasis model induced by imiquimod. We found that ItP (0.34 mA/cm2, 1 h) did not affect mRNA levels of inflammatory cytokines or epidermis thickness, indicating that ItP is a safe technology for psoriasis treatment. ItP of FK-Lipo suppressed the expression of inflammatory cytokines induced by imiquimod treatment to a greater extent than skin treated with FK506 ointment for 1 h. Furthermore, epidermis thickening was significantly suppressed only by ItP of FK-Lipo. Taken together, results of this study demonstrate the successful development of an efficient treatment for psoriasis by combining FK-Lipo and ItP, without disease aggravation associated with the weak electric current.

Enhanced topical paromomycin delivery for cutaneous leishmaniasis treatment: Passive and iontophoretic approaches

Conventional treatments for cutaneous leishmaniasis, a neglected vector-borne infectious disease, can frequently lead to serious adverse effects. Paromomycin (PAR), an aminoglycoside antibiotic, has been suggested for the topical treatment of disease-related lesions, but even when formulated in high drug-loading dosage forms, presents controversial efficacy. The presence of five ionizable amino groups hinder its passive cutaneous penetration but make PAR an excellent candidate for iontophoretic delivery. The objective of this study was to verify the feasibility of using iontophoresis for cutaneous PAR delivery and to propose a topical passive drug delivery system that could be applied between iontophoretic treatments. For this, in vitro iontophoretic experiments evaluated different application durations (10, 30, and 360 min), current densities (0.1, 0.25, and 0.5 mA/cm2), PAR concentrations (0.5 and 1.0 %), and skin models (intact and impaired porcine skin). In addition, 1 % PAR hydrogel had its penetration profile compared to 15 % PAR ointment in passive transport. Results showed iontophoresis could deliver suitable PAR amounts to dermal layers, even in short times and with impaired skin. Biodistribution assays showed both iontophoretic transport and the proposed hydrogel delivered higher PAR amounts to deeper skin layers than conventional ointment, even though applying 15 times less drug. To our knowledge, this is the first report of PAR drug delivery enhancement by iontophoresis. In summary, the association of iontophoresis with a topical application of PAR gel seems appropriate for improving cutaneous leishmaniasis treatment.

Advances in Transdermal Drug Delivery Systems: A Bibliometric and Patent Analysis

Transdermal drug delivery systems have become an intriguing research topic in healthcare technology and one of the most frequently developed pharmaceutical products in the global market. In recent years, researchers and pharmaceutical companies have made significant progress in developing new solutions in the field. This study sheds light on current trends, collaboration patterns, research hotspots, and emerging frontiers of transdermal drug delivery. Herein, a bibliometric and patent analysis of data recovered from Scopus and The Lens databases, respectively, is reported over the last 20 years. From 2000 to 2022, the annual global publications increased from 131 in 2000 to 659 in 2022. Researchers in the United States, China, and India produced the highest number of publications. Likewise, most patent applications have been filed in the USA, China, and Europe. The recovered patents are 7275, grouped into 2997 patent families, of which 314 were granted. This study could support the work of decision-makers, scientific managers, or scientists to create new business opportunities or save money, time, and intellectual capital, thereby defining when a research or technology project should be a priority or not.

Smartphone-based iontophoresis transdermal drug delivery system for cancer treatment

Cancer is a leading cause of the death worldwide. However, the conventional cancer therapy still suffers from several limitations, such as systemic side effects, poor efficacy, and patient compliance due to limited accessibility to the tumor site. To address these issues, the localized drug delivery system has emerged as a promising approach. In this study, we developed an iontophoresis-based transdermal drug delivery system (TDDS) controlled by a smartphone application for cancer treatment. Iontophoresis, a low-intensity electric current-based TDDS, enhances drug permeation across the skin to provide potential for localized drug delivery and minimize systemic side effects. The fundamental mechanism of our system was modeled using finite element analysis and its performance was corroborated through the flow-through skin permeation tests using a plastic-based microfluidic chip. The results of in vitro cell experiments and skin deposition tests successfully demonstrated that our smartphone-controlled iontophoresis system significantly enhanced the drug permeation for cancer treatment. Therefore, this hand-held smartphone-based iontophoresis TDDS could be a powerful tool for self-administrated anticancer drug delivery applications.

Intradermal Delivery of Naked mRNA Vaccines via Iontophoresis

Messenger RNA (mRNA) vaccines against infectious diseases and for anticancer immunotherapy have garnered considerable attention. Currently, mRNA vaccines encapsulated in lipid nanoparticles are administrated via intramuscular injection using a needle. However, such administration is associated with pain, needle phobia, and lack of patient compliance. Furthermore, side effects such as fever and anaphylaxis associated with the lipid nanoparticle components are also serious problems. Therefore, noninvasive, painless administration of mRNA vaccines that do not contain other problematic components is highly desirable. Antigen-presenting cells reside in the epidermis and dermis, making the skin an attractive vaccination site. Iontophoresis (ItP) uses weak electric current applied to the skin surface and offers a noninvasive permeation technology that enables intradermal delivery of hydrophilic and ionic substances. ItP-mediated intradermal delivery of biological macromolecules has also been studied. Herein, we review the literature on the use of ItP technology for intradermal delivery of naked mRNA vaccines which is expected to overcome the challenges associated with mRNA vaccination. In addition to the physical mechanism, we discuss novel biological mechanisms of iontophoresis, particularly ItP-mediated opening of the skin barriers and the intracellular uptake pathway, and how the combined mechanisms can allow for effective intradermal delivery of mRNA vaccines.

Development of an UHPLC-MS/MS method to determine cutaneous biodistribution of cannabidiol after topical application of cannabidiol gel assisted by iontophoresis

Cannabidiol has potential for use in skin disease therapy, so it is important to know the cutaneous biodistribution of cannabidiol after topical application of cannabidiol formulations. However, currently existing quantification methods for the investigation of cannabidiol skin distribution are not optimal. This study aimed to establish a method for the determination of cannabidiol in skin samples by UHPLC-MS/MS. A BEH C18 (50.0 × 2.1 mm, 2.5 μm) column was used; the mobile phase consisted of acetonitrile-0.1% formic acid (70:30, v/v), the flow rate was 0.2 μl·min-1 and the column temperature was 30°C. Positive-ion mode with multiple reaction monitoring detection was used to quantify cannabidiol (m/z 315.1 → 193.1) while diphenhydramine (m/z 256.3 → 167.08) served as the internal standard. Good linearity was shown in the range of 1-200 ng·ml-1 for cannabidiol with correlation coefficients of >0.999. The LLOQ was 1 ng·ml-1 . The intra-day and inter-day RSDs of cannabidiol were all <2%. A cryo-sectioning technique combined with the UHPLC-MS/MS method was used to successfully determine cannabidiol levels in a series of very thin skin layers.

Strategies to develop polymeric microneedles for controlled drug release

The remarkable appeal of microneedle controlled-release systems has captivated both the academic community and pharmaceutical industry due to their great potential for achieving spatiotemporally controlled release, coupled with their the minimally invasive nature and ease of application. Over the years, scientists have dedicated their efforts to advancing microneedle systems by manipulating the physicochemical properties of matrix materials, refining microneedle designs, and interfacing with external devices to provide tailored drug release profiles in a spatiotemporally controllable manner. Expanding upon our understanding of drug release mechanisms from polymeric microneedles, which include diffusion, swelling, degradation, triggering, and targeting, there is a growing focus on manipulating the location and rate of drug release through innovative microneedle designs. This burgeoning field of microneedle-based drug delivery systems offers further prospects for precise control over drug release. The design strategies of polymeric microneedle systems for temporally controlled and locally targeted release, as well as the delivery mechanisms by which drugs can be released from a microneedle system are critically reviewed in this work. Furthermore, this review also puts forward some perspectives on the potential and challenges involved in translating these microneedle-based delivery systems into the next generation therapies.

Novel Vehicles For Drug Delivery in Atopic Dermatitis: A Narrative Review

INTRODUCTION

Atopic dermatitis (AD) causes dry and itchy skin and inflammation that severely impairs the quality of life of affected children and adults. While topical glucocorticosteroid application is typically the first-line treatment of choice, steroid treatment is associated with side effects and, increasingly, patient concerns about prolonged use. Novel drugs and drug delivery vehicles are required for patients with AD.

OBJECTIVES

To summarize the current literature on novel topical agents for atopic dermatitis and novel delivery vehicles.

METHODS

A literature search was conducted, and a narrative review was compiled to summarize recent evidence.

RESULTS

Novel topical drugs approved or in late-phase clinical trials for the treatment of AD include the Janus kinase inhibitor ruxolitinib, the phosphodiesterase-4 inhibitors crisaborole, and roflumilast, and the aryl hydrocarbon receptor activator tapinarof. While current topical drugs for AD are delivered via creams, ointments, gels, and related vehicles, novel delivery approaches such as electrospun patches, sprays, liposomes, nanoparticles, and lasers are being developed to enhance transdermal delivery, reduce side effects, and increase treatment adherence.

CONCLUSIONS

Topical application of creams or ointments is currently the predominant vehicle for the delivery of atopic dermatitis drugs. In vitro studies on novel vehicles show promising results to overcome the issues associated with topical delivery. Still, these findings have to be corroborated by controlled studies with human patients in the future.

Lipid-based nanocarriers challenging the ocular biological barriers: Current paradigm and future perspectives

Eye is the most specialized and sensory body organ and treating eye diseases efficiently is necessary. Despite various attempts, the design of a consummate ophthalmic drug delivery system remains unsolved because of anatomical and physiological barriers that hinder drug transport into the desired ocular tissues. It is important to advance new platforms to manage ocular disorders, whether they exist in the anterior or posterior cavities. Nanotechnology has piqued the interest of formulation scientists because of its capability to augment ocular bioavailability, control drug release, and minimize inefficacious drug absorption, with special attention to lipid-based nanocarriers (LBNs) because of their cellular safety profiles. LBNs have greatly improved medication availability at the targeted ocular site in the required concentration while causing minimal adverse effects on the eye tissues. Nevertheless, the exact mechanisms by which lipid-based nanocarriers can bypass different ocular barriers are still unclear and have not been discussed. Thus, to bridge this gap, the current work aims to highlight the applications of LBNs in the ocular drug delivery exploring the different ocular barriers and the mechanisms viz. adhesion, fusion, endocytosis, and lipid exchange, through which these platforms can overcome the barrier characteristics challenges.

A system for bioelectronic delivery of treatment directed toward wound healing

The development of wearable bioelectronic systems is a promising approach for optimal delivery of therapeutic treatments. These systems can provide continuous delivery of ions, charged biomolecules, and an electric field for various medical applications. However, rapid prototyping of wearable bioelectronic systems for controlled delivery of specific treatments with a scalable fabrication process is challenging. We present a wearable bioelectronic system comprised of a polydimethylsiloxane (PDMS) device cast in customizable 3D printed molds and a printed circuit board (PCB), which employs commercially available engineering components and tools throughout design and fabrication. The system, featuring solution-filled reservoirs, embedded electrodes, and hydrogel-filled capillary tubing, is assembled modularly. The PDMS and PCB both contain matching through-holes designed to hold metallic contact posts coated with silver epoxy, allowing for mechanical and electrical integration. This assembly scheme allows us to interchange subsystem components, such as various PCB designs and reservoir solutions. We present three PCB designs: a wired version and two battery-powered versions with and without onboard memory. The wired design uses an external voltage controller for device actuation. The battery-powered PCB design uses a microcontroller unit to enable pre-programmed applied voltages and deep sleep mode to prolong battery run time. Finally, the battery-powered PCB with onboard memory is developed to record delivered currents, which enables us to verify treatment dose delivered. To demonstrate the functionality of the platform, the devices are used to deliver H[Formula: see text] in vivo using mouse models and fluoxetine ex vivo using a simulated wound environment. Immunohistochemistry staining shows an improvement of 35.86% in the M1/M2 ratio of H[Formula: see text]-treated wounds compared with control wounds, indicating the potential of the platform to improve wound healing.

Microneedle-based glucose monitoring: a review from sampling methods to wearable biosensors

Blood glucose (BG) monitoring is critical for diabetes management. In recent years, microneedle (MN)-based technology has attracted emerging attention in glucose sensing and detection. In this review, we summarized MN-based sampling for glucose collection and glucose analysis in detail. First, different principles of MN-based biofluid extraction were elaborated, including external negative pressure, capillary force, swelling force and iontophoresis, which would guide the shape design and material optimization of MNs. Second, MNs coupled with different analysis approaches, including Raman methods, colorimetry, fluorescence, and electrochemical sensing, were emphasized to exhibit the trend towards highly integrated wearable sensors. Finally, the future development prospects of MN-based devices were discussed.

Skin and Artificial Skin Models in Electrical Sensing Applications

Skin electrical properties play a significant role in recording biopotentials by using electrophysiological sensors. To test and evaluate sensor systems, it is commonly accepted to employ artificial skin models due to complications associated with testing on living tissues. The first goal of this Review is to provide a systematic understanding of the relation between skin structure and skin electrochemical behavior at an appropriate depth for electrophysiological sensing applications through a focus on skin structure, electrochemical properties of skin, and theoretical models (equivalent circuits) representing skin electrochemical behavior. The second goal is to review artificial skin models mimicking the electrochemical properties of skin and to give suggestions for future studies on relevant skin models based on a comparison between the behavior of skin and that of artificial skin models. The Review aims to help the reader to analyze the relation between the structure, elements of the equivalent circuits, and the resulting impedance data for both skin and artificial skin models.

Transdermal Delivery of Insulin Using Combination of Iontophoresis and Deep Eutectic Solvents as Chemical Penetration Enhancers: In Vitro and in Vivo Evaluations

A serious challenge in transdermal iontophoresis (IP) delivery of insulin (INS) is the low permeability of the drug across the skin. In this paper, we introduced deep eutectic solvent (DESs) as novel chemical penetration enhancers (CPEs) for transdermal IP of INS across rat skin, both in vitro and in vivo. Three different DESs based on choline chloride (ChCl), namely, ChCl/UR (ChCl and urea), ChCl/GLY (ChCl and glycerol), and ChCl/EG (ChCl and ethylene glycol) in the 1:2 molar ratios have been prepared. To evaluate the capability of studied DESs as CPEs for IP delivery of INS, the rat skin sample was treated with each DES. The effects of different experimental parameters (current density, formulation pH, INS concentration, NaCl concentration, and treatment time) on the in vitro transdermal iontophoretic delivery of INS were investigated. The in vitro permeation studies exhibited that INS was easily delivered employing ChCl/EG, and ChCl/GLY treatments, compared with ChCl/UR: the cumulative amount of permeated INS at the end of the experiment (Q24h) was found to be 131.0, 89.4, and 29.6 µg cm-2 in the presence of ChCl/EG, ChCl/GLY, and ChCl/UR, respectively. The differences in Q24h values of INS are due to the different capabilities of the studied DESs to treat the epidermis layer of skin. In vivo experiments revealed that the blood glucose level in diabetic rats could be decreased using ChCl/EG, and ChCl/GLY as novel CPEs in the IP delivery of INS. The presented work will open new doors towards searching for novel CPEs in the development of transdermal IP of INS.

Iontophoresis on Porcine and Human Gingiva

PURPOSE

Iontophoresis is a noninvasive method that enhances drug delivery using an electric field. This method can improve drug delivery to the tissues in the oral cavity. The effects of iontophoresis on gingival drug delivery have not been investigated. The objectives of this study were to (a) determine the flux enhancement of model permeants across porcine and human gingiva during iontophoresis, (b) examine the transport mechanisms of gingival iontophoresis, and (c) evaluate the potential of iontophoretically enhanced delivery for three model drugs lidocaine, ketorolac, and chlorhexidine.

METHODS

Passive and iontophoretic fluxes were determined with porcine and human gingiva using a modified Franz diffusion cell and model drugs and permeants. To investigate the transport mechanisms of iontophoresis, the enhancement from the direct-field effect was determined by positively and negatively charged model permeants. The electroosmosis enhancement effect was determined with neutral permeants of different molecular weight. The alteration of the gingival barrier due to electropermeabilization was evaluated using electrical resistance measurements.

RESULTS

Significant flux enhancement was observed during gingival iontophoresis. The direct-field effect was the major mechanism governing the iontophoretic transport of the charged permeants. Electroosmosis was from anode to cathode. The effective pore radius of the iontophoretic transport pathways in the porcine gingiva was ~0.68 nm. Irreversible electropermeabilization was observed after 2 and 4 h of iontophoresis under the conditions studied.

CONCLUSION

Iontophoresis could enhance drug delivery and reduce transport lag time, showing promise for gingival drug delivery.

Biocompatible topical delivery system of high-molecular-weight hyaluronan into human stratum corneum using magnesium chloride

Non-invasive delivery of hyaluronan into the stratum corneum (SC) is extremely difficult because of its high molecular weight and the strong barrier of the SC. We developed a safe method of administering hyaluronan into the human SC and determined its penetration route. The amount of hyaluronan that penetrated into the SC was 1.5-3 times higher in the presence of magnesium chloride hexahydrate (MgCl₂) than other metal chlorides. The root-mean-square radius of hyaluronan in water decreased with the addition of MgCl₂. Moreover, MgCl₂ solutions maintained their dissolved state on a plastic plate for a long time, suggesting that size compaction and inhibition of hyaluronan precipitation on the skin enhanced hyaluronan into the SC. Our results also strongly suggest that an intercellular route contributes to the penetration of hyaluronan from the upper to the middle layer of the SC. No disruption to the SC barrier was observed after continuous use once a day for 1 month, demonstrating the potential of our method for the safe, topical application of hyaluronan.

Investigation of the antimicrobial effect of anodic iontophoresis on Gram-positive and Gram-negative bacteria for skin infections treatment

Iontophoresis, a non-invasive application of a constant low-intensity electric current, is a promising strategy to accelerate wound healing. Although its mechanisms are not yet fully elucidated, part of its action seems related to inhibiting bacteria growth. This work aimed to investigate the antimicrobial effect of iontophoresis using Staphylococcus epidermidis and Escherichia coli strains, Gram-positive and Gram-negative bacteria, respectively. Anodic iontophoresis was applied to each bacterial suspension using Ag/AgCl electrodes, and bacteria viability was evaluated after 24 h incubation by counting colony-forming units. A Quality-by-Design approach was performed to assess the influence of the iontophoresis' intensity and application time on bacterial viability. Cell morphology was evaluated by scanning electron microscopy. Iontophoresis showed antimicrobial effects on the Gram-positive bacteria only at 5 mA and 60 min application. However, a linear relationship was observed between intensity and application time for the Gram-negative one, causing drastic morphological changes and up to 98 % death. The cell wall of Gram-negative bacteria seems more susceptible to disorganization triggered by iontophoresis-induced ion transport than Gram-positive ones. Therefore, anodic iontophoresis can be a powerful ally in controlling Gram-negative bacteria proliferation in wounds.

A Conformable Ultrasound Patch for Cavitation-Enhanced Transdermal Cosmeceutical Delivery

Increased consumer interest in healthy-looking skin demands a safe and effective method to increase transdermal absorption of innovative therapeutic cosmeceuticals. However, permeation of small-molecule drugs is limited by the innate barrier function of the stratum corneum. Here, a conformable ultrasound patch (cUSP) that enhances transdermal transport of niacinamide by inducing intermediate-frequency sonophoresis in the fluid coupling medium between the patch and the skin is reported. The cUSP consists of piezoelectric transducers embedded in a soft elastomer to create localized cavitation pockets (0.8 cm² , 1 mm deep) over larger areas of conformal contact (20 cm² ). Multiphysics simulation models, acoustic spectrum analysis, and high-speed videography are used to characterize transducer deflection, acoustic pressure fields, and resulting cavitation bubble dynamics in the coupling medium. The final system demonstrates a 26.2-fold enhancement in niacinamide transport in a porcine model in vitro with a 10 min ultrasound application, demonstrating the suitability of the device for short-exposure, large-area application of sonophoresis for patients and consumers suffering from skin conditions and premature skin aging.

Effect of interstitial fluid pH on transdermal glucose extraction by reverse iontophoresis

Reverse iontophoresis (RI) is a promising technology in the field of continuous glucose monitoring (CGM), offering significant advantages such as finger-stick-free operation, wearability, and non-invasiveness. In the glucose extraction process based on RI, the pH of the interstitial fluid (ISF) is a critical factor that needs further investigation, as it directly influences the accuracy of transdermal glucose monitoring. In this study, a theoretical analysis was conducted to investigate the mechanism by which pH affects the glucose extraction flux. Modeling and numerical simulations performed at different pH conditions indicated that the zeta potential was significantly impacted by the pH, thereby altering the direction and flux of the glucose iontophoretic extraction. A screen-printed glucose biosensor integrated with RI extraction electrodes was developed for ISF extraction and glucose monitoring. The accuracy and stability of the ISF extraction and glucose detection device were demonstrated with extraction experiments using different subdermal glucose concentrations ranging from 0 to 20 mM. The extraction results for different ISF pH values exhibited that at 5 mM and 10 mM subcutaneous glucose, the extracted glucose concentration was increased by 0.08212 mM and 0.14639 mM for every 1 pH unit increase, respectively. Furthermore, the normalized results for 5 mM and 10 mM glucose demonstrated a linear correlation, indicating considerable potential for incorporating a pH correction factor in the blood glucose prediction model used to calibrate glucose monitoring.

Transdermal on-demand drug delivery based on an iontophoretic hollow microneedle array system

Transdermal drug delivery has emerged as an alternative administration route for therapeutic drugs, overcoming current issues in oral and parenteral administration. However, this technology is hindered by the low permeability of the stratum corneum of the skin. In this work, we develop a synergic combination of two enhancing technologies to contribute to an improved and on-demand drug delivery through an iontophoretic system coupled with hollow microneedles (HMNs). For the first time, a polymeric HMN array coupled with integrated iontophoresis for the delivery of charged molecules and macromolecules (e.g. proteins) is devised. To prove the concept, methylene blue, fluorescein sodium, lidocaine hydrochloride, and bovine serum albumin-fluorescein isothiocyanate conjugate (BSA-FITC) were first tested in an in vitro setup using 1.5% agarose gel model. Subsequently, the ex vivo drug permeation study using a Franz diffusion cell was conducted, exhibiting a 61-fold, 43-fold, 54-fold, and 17-fold increment of the permeation of methylene blue, fluorescein sodium, lidocaine hydrochloride, and BSA-FITC, respectively, during the application of 1 mA cm^-2 current for 6 h. Moreover, the total amount of drug delivered (i.e. in the skin and receptor compartment) was analysed to untangle the different delivery profiles according to the types of molecule. Finally, the integration of the anode and cathode into an iontophoretic hollow microneedle array system (IHMAS) offers the full miniaturisation of the concept. Overall, the IHMAS device provides a versatile wearable technology for transdermal on-demand drug delivery that can improve the administration of personalised doses, and potentially enhance precision medicine.

Non-invasive electrochemical immunosensor for reverse iontophoretic determination of cardiac troponins (cTnT & cTnI) in a simulated artificial skin model. Significance of raw DPV and CV data for chemometric discrimination

Electrochemical immunosensors coupled with reverse iontophoresis (RI) for noninvasive determination of cardiac troponins were developed and validated according to ICH Q2 (R1) guideline. Linearity was in 0.01-10 and 100-500 ng/mL ranges. LODs (ng/mL) were in 6-25 × 10-4, while LOQs (μg/mL) were in 18-7.5 × 10-4 range. Chemometric evaluation was performed on raw data simply by principle component analysis and cluster analysis to discriminate stages of immunosensors. This is the first demonstration of RI determination of cardiac troponins so far. Findings of the current manuscript have great potential to develop point of care diagnostic systems for major cardiac events, where high sensitivity and specificity are required.

Iontophoresis for the cutaneous delivery of nanoentraped drugs

INTRODUCTION

The skin is an attractive route for drug delivery. However, the stratum corneum is a critical limiting barrier for drug permeation. Nanoentrapment is a way to enhance cutaneous drug delivery, by diverse mechanisms, with a notable trend of nanoparticles accumulating into the hair follicles when topically applied. Iontophoresis is yet another way of increasing drug transport by applying a mild electrical field that preferentially passes through the hair follicles, for being the pathway of lower resistance. So, iontophoresis application to nanocarriers could further increase actives accumulation into the hair follicles, impacting cutaneous drug delivery.

AREAS COVERED

In this review, the authors aimed to discuss the main factors impacting iontophoretic skin transport when combining nanocarriers with iontophoresis. We further provide an overview of the conditions in which this combination has been studied, the characteristics of nanosystems employed, and hypothesize why the association has succeeded or failed to enhance drug permeation.

EXPERT OPINION

Nanocarriers and iontophoresis association can be promising to enhance cutaneous drug delivery. For better results, the electroosmotic contribution to the iontophoretic transport, mainly of negatively charged nanocarriers, charge density, formulation pH, and skin models should be considered. Moreover, the transfollicular pathway should be considered, especially when designing the nanocarriers.

Extraction of phytochemicals from the pomegranate (Punica granatum L., Punicaceae) by reverse iontophoresis

Plant metabolic profiling can provide a wealth of information regarding the biochemical status of the organism, but sample acquisition typically requires an invasive and/or destructive extraction process. Reverse iontophoresis (RI) imposes a small electric field across a biological membrane to substantially enhance the transport of charged and polar compounds and has been employed, in particular, to extract biomarkers of interest across human skin. The objective of this work was to examine the capability of RI to sample phytochemicals in a minimally invasive fashion in fructo (i.e., from the intact fruit). RI was principally used to extract a model, bioactive compound - specifically, ellagic acid - from the fruit peel of Punica granatum L. The RI sampling protocol was refined using isolated peel, and a number of experimental factors were examined and optimised, including preparation of the peel samples, the current intensity applied and the pH of the medium into which samples were collected. The most favourable conditions (3 mA current for a period of 1 hour, into a buffer at pH 7.4) were then applied to the successful RI extraction of ellagic acid from intact pomegranates. Multiple additional phytochemicals were also extracted and identified by liquid chromatography with tandem mass spectrometry (LC-MS/MS). A successful proof-of-concept has been achieved, demonstrating the capability to non-destructively extract phytochemicals of interest from intact fruit.

Design, optimization and evaluation of dexamethasone-loaded microneedles for inflammatory disorders

Dexamethasone (Dex) is a popular and highly potent anti-inflammatory drug, frequently used to treat a wide range of inflammatory disorders. However, the existing oral and parenteral delivery modes have several limitations, including systemic adverse effects and reduced patient compliance. This study aimed to develop a biodegradable microneedle (MN)-based transdermal delivery system capable of sustained, safe and effective delivery of Dex. A Quality by Design (QbD) approach was applied to design the Dex-loaded MN arrays. The formulation variables were optimized using a central composite design (CCD) model, generated with the statistical software package Design- Expert®. The optimized MNs were sharp, with heights ranging between 800 and 900 µm, appropriate for transdermal delivery. The MN arrays did not exhibit any cytotoxic effects on the fibroblast and keratinocyte cells. Moreover, the ex vivo studies confirmed the enhanced efficacy of MN-mediated skin permeation of Dex compared to passive permeation of drug solution. Finally, the in vivo anti-inflammatory efficacy was investigated using the carrageenan-induced rat paw edema model. The efficacy of the MN arrays to inhibit paw edema formation was found to be comparable to that of intravenous Dex injection and significantly greater than topical solution. Cytokine analysis also revealed that application of MN arrays downregulated the expressions of pro-inflammatory cytokines and upregulated the expressions of anti-inflammatory cytokines. Overall, the findings suggest that MN array could be a safe, easy, effective and minimally invasive alternative to the existing means of Dex delivery and could potentially be used for the treatment of inflammatory disorders.