Therapeutic transdermal drug innovation from 2000 to 2014: current status and outlook

Advances in Transdermal Delivery of Antimicrobial Peptides for Wound Management: Biomaterial-Based Approaches and Future Perspectives

Antimicrobial peptides (AMPs), distinguished by their cationic and amphiphilic nature, represent a critical frontier in the battle against antimicrobial resistance due to their potent antimicrobial activity and a broad spectrum of action. However, the clinical translation of AMPs faces hurdles, including their susceptibility to degradation, limited bioavailability, and the need for targeted delivery. Transdermal delivery has immense potential for optimizing AMP administration for wound management. Leveraging the skin's accessibility and barrier properties, transdermal delivery offers a noninvasive approach that can circumvent systemic side effects and ensure sustained release. Biomaterial-based delivery systems, encompassing nanofibers, hydrogels, nanoparticles, and liposomes, have emerged as key players in enhancing the efficacy of transdermal AMP delivery. These biomaterial carriers not only shield AMPs from enzymatic degradation but also provide controlled release mechanisms, thereby elevating stability and bioavailability. The synergistic interaction between the transdermal approach and biomaterial-facilitated formulations presents a promising strategy to overcome the multifaceted challenges associated with AMP delivery. Integrating advanced technologies and personalized medicine, this convergence allows the reimagining of wound care. This review amalgamates insights to propose a pathway where AMPs, transdermal delivery, and biomaterial innovation harmonize for effective wound management.

Pulsed Laser Photo-Crosslinking of Gelatin Methacryloyl Hydrogels for the Controlled Delivery of Chlorpromazine to Combat Antimicrobial Resistance

Hydrogels are ideal candidates for the sustained local administration of antimicrobial drugs because they have customizable physicochemical properties that allow drug release kinetics to be controlled and potentially address the issue of systemic side effects. Consequently, the purpose of this study was to use 266 nm-pulsed laser beams to photo-crosslink gelatin methacryloyl hydrogels using Irgacure 2959 as a photo-initiator to reduce the curing time and to have an online method to monitor the process, such as laser-induced fluorescence. Additionally, irradiated chlorpromazine was loaded into the hydrogels to obtain a drug delivery system with antimicrobial activity. These hydrogels were investigated by UV–Vis and FTIR absorption spectroscopy, scanning electron microscopy, and laser-induced fluorescence spectroscopy and their structural and morphological characteristics, swelling behavior, and drug release profile were obtained. As a result the morphology, swelling behavior, and drug release profile were influenced by both the energy of the laser beam and the exposure time. The optimal hydrogel was obtained after 1 min of laser irradiation for Irgacure 2959 at 0.05% w/v concentration and gelatin methacryloyl at 10% w/v concentration. The hydrogels loaded with irradiated chlorpromazine show significant antimicrobial activity against Staphylococcus aureus and MRSA bacteria and a non-cytotoxic effect against L929 fibroblast cell lines.

Exogenous testosterone replacement therapy versus raising endogenous testosterone levels: current and future prospects

Testosterone replacement therapy is an important treatment option for men with low testosterone and symptomatic hypogonadism. Various formulations of exogenous testosterone replacement therapy exist, including oral, buccal, intramuscular, transdermal, subdermal, and nasal preparations. However, exogenous testosterone replacement therapy is a double-edged sword, posing risks to fertility due to negative feedback mechanisms on the hypothalamic-pituitary-gonadal (HPG) axis, which is the main regulator of testosterone production and spermatogenesis in males. Alternative pharmacologic therapies are being used to increase endogenous testosterone levels while attempting to preserve fertility and function of the HPG axis. These include selective estrogen receptor modulators, gonadotropins, and aromatase inhibitors. This review focuses on overviewing and comparing the currently available methods of exogenous testosterone replacement therapy, alternative treatments to increasing endogenous testosterone, and novel treatments that are currently under investigation to normalize testosterone levels while preserving the function of the HPG axis. In conclusion, reports suggest that, though Testosterone replacement therapy is an important way to restore testosterone levels and reduce symptoms associated with low testosterone, it is often difficult to decide which treatment to select for patients with testosterone deficiency. Several factors need to be considered to decide on optimal therapy option for the patient which include but are not limited to safety, efficacy, cost-effectiveness, dosing flexibility, and side effects. Alternative approaches which aim to improve endogenous testosterone production and preserve fertility are promising but still are at their initial stages of development. Ultimately, patient-centered decision making is paramount to appropriate treatment selection.

Statistical Considerations in Assessing In Vivo Adhesion with Transdermal and Topical Delivery Systems for New Drug Applications

Proper adhesion plays a critical role in maintaining a consistent, efficacious, and safe drug delivery profile for transdermal and topical delivery systems (TDS). As such, in vivo skin adhesion studies are recommended by regulatory agencies to support the approval of TDS in new drug applications (NDAs). A draft guidance for industry by the US Food and Drug Administration outlines a non-inferiority comparison between a test product and its reference product for generic TDS in abbreviated new drug applications (ANDAs). However, the statistical method is not applicable for evaluating adhesion of TDS for NDAs, because no reference product exists. In this article, we explore an alternative primary endpoint and a one-sided binomial test to evaluate in vivo adhesion of TDS in NDAs. Statistical considerations related to the proposed approach are discussed. To understand its potential use, the proposed approach is applied to data sets of in vivo adhesion studies from selected NDAs and ANDAs.

Advanced drug delivery 2020 and beyond: Perspectives on the future

Drug delivery systems are developed to maximize drug efficacy and minimize side effects. As drug delivery technologies improve, the drug becomes safer and more comfortable for patients to use. During the last seven decades, extraordinary progress has been made in drug delivery technologies, such as systems for long-term delivery for months and years, localized delivery, and targeted delivery. The advances, however, will face a next phase considering the future technologies we need to overcome many physicochemical barriers for new formulation development and biological unknowns for treating various diseases. For immediate and long-term progress into the future, the drug delivery field should use time and resources for more translatable research ideas. The drug delivery discipline has to continue working on basic, applied, translational, and clinical research in a concerted manner to produce drug delivery systems that work for patients. It is a time to focus our attention on things that matter. It is also a time to develop realistic research goals and outcomes, diversify drug delivery technologies, and take the collective responsibility for our actions.

Passive delivery of protein drugs through transdermal route

Skin is the largest external organ in the human body but its use for therapeutic purposes has been minimal. Stratum corneum residing on the uppermost layer of the skin provides a tough barrier to transport the drugs across the skin. Very small group of drugs sharing Lipinski properties, i.e. drugs having molecular weight not larger than 500 Da, having high lipophilicity and optimum polarity are fortunate enough to be used on skin therapeutics. But, at a time where modern therapeutics is slowly shifting from use of small molecular drugs towards the use of macromolecular therapeutic agents such as peptides, proteins and nucleotides in origin, skin therapeutics need to be evolved accordingly to cater the delivery of these agents. Physical technologies like iontophoresis, laser ablation, micro-needles and ultrasound, etc. have been introduced to enhance skin permeability. But their success is limited due to their complex working mechanisms and involvement of certain irreversible skin damage in some or other way. This review therefore explores the delivery strategies for transport of mainly peptide and protein drugs that do not involve any injuries (non-invasive) to the skin termed as passive delivery techniques. Chemical enhancers, nanocarriers, certain biological peptides and miscellaneous approaches like prodrugs are also thoroughly reviewed for their applications in protein delivery.

Protein tyrosine phosphatase conjugated with a novel transdermal delivery peptide, astrotactin 1-derived peptide recombinant protein tyrosine phosphatase (AP-rPTP), alleviates both atopic dermatitis-like and psoriasis-like dermatitis

BACKGROUND

Atopic dermatitis (AD) and psoriasis are the 2 most common chronic inflammatory skin diseases. There is an unmet medical need to overcome limitations for transcutaneous drug development posed by the skin barrier.

OBJECTIVE

We aimed to identify a novel transdermal delivery peptide and to develop a transcutaneously applicable immunomodulatory protein for treating AD and psoriasis.

METHODS

We identified and generated reporter proteins conjugated to astrotactin 1-derived peptide (AP), a novel transdermal delivery peptide of human origin, and analyzed the intracellular delivery efficiency of these proteins in mouse and human skin cells and tissues using multiphoton confocal microscopy. We also generated a recombinant therapeutic protein, AP-recombinant protein tyrosine phosphatase (rPTP), consisting of the phosphatase domain of the T-cell protein tyrosine phosphatase conjugated to AP. The immunomodulatory function of AP-rPTP was confirmed in splenocytes on cytokine stimulation and T-cell receptor stimulation. Finally, we confirmed the in vivo efficacy of AP-rPTP transdermal delivery in patients with oxazolone-induced contact hypersensitivity, ovalbumin-induced AD-like, and imiquimod-induced psoriasis-like skin inflammation models.

RESULTS

AP-conjugated reporter proteins exhibited significant intracellular transduction efficacy in keratinocytes, fibroblasts, and immune cells. In addition, transcutaneous administration of AP-dTomato resulted in significant localization into the dermis and epidermis in both mouse and human skin. AP-rPTP inhibited phosphorylated signal transducer and activator of transcription (STAT) 1, STAT3, and STAT6 in splenocytes and also regulated T-cell activation and proliferation. Transcutaneous administration of AP-rPTP through the paper-patch technique significantly ameliorated skin tissue thickening, inflammation, and cytokine expression in both AD-like and psoriasis-like dermatitis models.

CONCLUSION

We identified a 9-amino-acid novel transdermal delivery peptide, AP, and demonstrated its feasibility for transcutaneous biologic drug development. Moreover, AP-rPTP is a novel immunomodulatory drug candidate for human dermatitis.

Microneedle-mediated delivery of donepezil: Potential for improved treatment options in Alzheimer's disease

Transdermal drug delivery is an attractive route of drug administration; however, there are relatively few marketed transdermal products. To increase delivery across the skin, strategies to enhance skin permeability are widely investigated, with microneedles demonstrating particular promise. Hydrogel-forming microneedles are inserted into the skin, and following dissolution of a drug loaded reservoir and movement of the drug through the created channels, the microneedle array is removed intact, and can then be readily and safely discarded. This study presents the formulation and evaluation of an integrated microneedle patch containing the Alzheimer's drug, donepezil hydrochloride. The integrated patch consisted of hydrogel-forming microneedles in combination with a donepezil hydrochloride containing film. Formulation and characterisation of plasticised films, prepared from poly(vinylpyrrolidone) or poly (methyl vinyl ether co-maleic anhydride/acid) (Gantrez®) polymers, is presented. Furthermore, in vitro permeation of donepezil hydrochloride across neonatal porcine skin from the patches was investigated, with 854.71μg±122.71μg donepezil hydrochloride delivered after 24h, using the optimum patch formulation. Following administration of the patch to an animal model, plasma concentrations of 51.8±17.6ng/mL were obtained, demonstrating the success of this delivery platform for donepezil hydrochloride.

A biodegradable, biocompatible transdermal device derived from carboxymethyl cellulose and multi-walled carbon nanotubes for sustained release of diclofenac sodium

A hybrid nanocomposite hydrogel (CMC–MWCNT) has been fabricated using carboxymethyl cellulose (CMC) and acid-functionalized multi-walled carbon nanotubes (MWCNTs) at room temperature for transdermal delivery of diclofenac sodium.

Future of the transdermal drug delivery market--have we barely touched the surface?

INTRODUCTION

Transdermal drug delivery is the movement of drugs across the skin for absorption into the systemic circulation. Transfer of the drug can occur via passive or active means; passive transdermal products do not disrupt the stratum corneum to facilitate delivery whereas active technologies do. Due to the very specific physicochemical properties necessary for successful passive transdermal drug delivery, this sector of the pharmaceutical industry is relatively small. There are many well-documented benefits of this delivery route however, and as a result there is great interest in increasing the number of therapeutic substances that can be delivered transdermally.

AREAS COVERED

This review discusses the various transdermal products that are currently/have been marketed, and the paths that led to their success, or lack of. Both passive and active transdermal technologies are considered with the advantages and limitations of each highlighted. In addition to marketed products, technologies that are in the investigative stages by various pharmaceutical companies are reviewed.

EXPERT OPINION

Passive transdermal drug delivery has made limited progress in recent years, however with the ongoing intense research into active technologies, there is great potential for growth within the transdermal delivery market. A number of active technologies have already been translated into marketed products, with other platforms including microneedles, rapidly progressing towards commercialisation.