The application of skin metabolomics in the context of transdermal drug delivery

Bibliometric analysis and visualization of transdermal drug delivery research in the last decade: global research trends and hotspots

Background: Transdermal delivery has become a crucial field in pharmaceutical research. There has been a proliferation of innovative methods for transdermal drug delivery. In recent years, the number of publications regarding transdermal drug delivery has been rising rapidly. To investigate the current research trends and hotspots in transdermal drug delivery, a comprehensive bibliometric analysis was performed. Methods: An extensive literature review was conducted to gather information on transdermal drug delivery that had been published between 2003 and 2022. The articles were obtained from the Web of Science (WOS) and the National Center for Biotechnology Information (NCBI) databases. Subsequently, the collected data underwent analysis and visualization using a variety of software tools. This approach enables a deeper exploration of the hotspots and emerging trends within this particular research domain. Results: The results showed that the number of articles published on transdermal delivery has increased steadily over the years, with a total of 2,555 articles being analyzed. The most frequently cited articles were related to the optimization of drug delivery and the use of nanotechnology in transdermal drug delivery. The most active countries in the field of transdermal delivery research were the China, United States, and India. Furthermore, the hotspots over the past 2 decades were identified (e.g., drug therapy, drug delivery, and pharmaceutical preparations and drug design). The shift in research focus reflects an increasing emphasis on drug delivery and control release, rather than simply absorption and penetration, and suggests a growing interest in engineering approaches to transdermal drug delivery. Conclusion: This study provided a comprehensive overview of transdermal delivery research. The research indicated that transdermal delivery would be a rapidly evolving field with many opportunities for future research and development. Moreover, this bibliometric analysis will help researchers gain insights into transdermal drug delivery research's hotspots and trends accurately and quickly.

Rapid skin biomarker discovery using hydrogel-phase sampling followed by semi-automated liquid-phase re-extraction high-resolution mass spectrometry

A facile and rapid skin metabolomics protocol is proposed. The liquid microjunction-surface sampling probe system has been partly automated, and used in conjunction with hydrogel probes for skin metabolite analysis. A control device was built to precisely control the segmented solvent flow and analyte re-extraction into the liquid microjunction. This mode provides rapid online re-extraction of the analytes from hydrogel probes. Humectant was added to the hydrogel, and moist heat treatment was used to make the hydrogel probes rugged for sampling in the clinical setting. The developed method was validated for the analysis of choline - a putative biomarker of psoriasis. A linear relationship over six calibration levels from 3.18 × 10^-5 to 3.18 × 10^-4 mol m^-2 has been obtained. The limit of detection was 6.6 × 10^-6 mol m^-2, while the recoveries range from 92 to 109%. The within-run and between-run precision were evaluated and the coefficients of variation range from 1.84 to 7.13%. Furthermore, the developed method has been used to screen patients (n = 10) and healthy participants (control group; n = 10) for psoriasis-related skin metabolites. Metabolomic profiling of the skin excretion-related signals identified potential biomarkers of psoriasis: choline, pipecolic acid, ornithine, urocanic acid, and methionine.

Skin Cancer Metabolic Profile Assessed by Different Analytical Platforms

Skin cancer, including malignant melanoma (MM) and keratinocyte carcinoma (KC), historically named non-melanoma skin cancers (NMSC), represents the most common type of cancer among the white skin population. Despite decades of clinical research, the incidence rate of melanoma is increasing globally. Therefore, a better understanding of disease pathogenesis and resistance mechanisms is considered vital to accomplish early diagnosis and satisfactory control. The "Omics" field has recently gained attention, as it can help in identifying and exploring metabolites and metabolic pathways that assist cancer cells in proliferation, which can be further utilized to improve the diagnosis and treatment of skin cancer. Although skin tissues contain diverse metabolic enzymes, it remains challenging to fully characterize these metabolites. Metabolomics is a powerful omics technique that allows us to measure and compare a vast array of metabolites in a biological sample. This technology enables us to study the dermal metabolic effects and get a clear explanation of the pathogenesis of skin diseases. The purpose of this literature review is to illustrate how metabolomics technology can be used to evaluate the metabolic profile of human skin cancer, using a variety of analytical platforms including gas chromatography-mass spectrometry (GC-MS), liquid chromatography-mass spectrometry (LC-MS), and nuclear magnetic resonance (NMR). Data collection has not been based on any analytical method.

Poly(lactic-co-glycolic) Acid (PLGA) Nanoparticles and Transdermal Drug Delivery: An Overview

BACKGROUND

Biodegradable polymeric nanoparticles have garnered pharmaceutical industry attention throughout the past decade. PLGA [Poly(lactic-co-glycolic acid)] is an excellent biodegradable polymer explored for the preparation of nanoparticles that are administered through various routes like intravenous and transdermal. PLGA's versatility makes it a good choice for the preparation of nanoparticles.

OBJECTIVE

The main objective of this review paper was to summarize methods of preparation and characterization of PLGA nanoparticles along with their role in the transdermal delivery of various therapeutic agents.

METHODS

A literature survey for the present review paper was done using various search engines like Pubmed, Google Scholar, and Science Direct.

RESULTS

In comparison to traditional transdermal administration systems, PLGA nanoparticles have demonstrated several benefits in preclinical investigations, including fewer side effects, low dosage frequency, high skin permeability, and simplicity of application.

CONCLUSION

PLGA nanoparticles can be considered efficient nanocarriers for the transdermal delivery of drugs. Nevertheless, the clinical investigation of PLGA nanoparticles for the transdermal administration of therapeutic agents remains a formidable obstacle.

Adapting Clofazimine for Treatment of Cutaneous Tuberculosis by Using Self-Double-Emulsifying Drug Delivery Systems

Although chemotherapeutic treatment regimens are currently available, and considerable effort has been lavished on the development of new drugs for the treatment of tuberculosis (TB), the disease remains deeply intractable and widespread. This is due not only to the nature of the life cycle and extraordinarily disseminated habitat of the causative pathogen, principally Mycobacterium tuberculosis (Mtb), in humans and the multi-drug resistance of Mtb to current drugs, but especially also to the difficulty of enabling universal treatment of individuals, immunocompromised or otherwise, in widely differing socio-economic environments. For the purpose of globally eliminating TB by 2035, the World Health Organization (WHO) introduced the "End-TB" initiative by employing interventions focusing on high impact, integrated and patient-centered approaches, such as individualized therapy. However, the extraordinary shortfall in stipulated aims, for example in actual treatment and in TB preventative treatments during the period 2018-2022, latterly and greatly exacerbated by the COVID-19 pandemic, means that even greater pressure is now placed on enhancing our scientific understanding of the disease, repurposing or repositioning old drugs and developing new drugs as well as evolving innovative treatment methods. In the specific context of multidrug resistant Mtb, it is furthermore noted that the incidence of extra-pulmonary TB (EPTB) has significantly increased. This review focusses on the potential of utilizing self-double-emulsifying drug delivery systems (SDEDDSs) as topical drug delivery systems for the dermal route of administration to aid in treatment of cutaneous TB (CTB) and other mycobacterial infections as a prelude to evaluating related systems for more effective treatment of CTB and other mycobacterial infections at large. As a starting point, we consider here the possibility of adapting the highly lipophilic riminophenazine clofazimine, with its potential for treatment of multi-drug resistant TB, for this purpose. Additionally, recently reported synergism achieved by adding clofazimine to first-line TB regimens signifies the need to consider clofazimine. Thus, the biological effects and pharmacology of clofazimine are reviewed. The potential of plant-based oils acting as emulsifiers, skin penetration enhancers as well as these materials behaving as anti-microbial components for transporting the incorporated drug are also discussed.

Amphiphilic Poly-N-vinylpyrrolidone Nanoparticles as Carriers for Nonsteroidal, Anti-Inflammatory Drugs: Pharmacokinetic, Anti-Inflammatory, and Ulcerogenic Activity Study

Nanoparticles are increasingly utilized as drug delivery agents. Previously, we have developed a drug delivery system based on amphiphilic derivatives of poly-N-vinylpyrrolidone (PVP-OD4000) with excellent biocompatibility. In the current study, we assessed the pharmacokinetics, anti-inflammatory profile, and ulcerogenic potential of indomethacin (IMC)-loaded PVP-OD4000 nanoparticles compared to the free drug. Wistar male rats were utilized for a pharmacokinetics study and an anti-inflammatory study. Loaded IMC exhibited a slower elimination rate (p < 0.05) and a higher blood plasma concentration at 8 and 24 h after intraperitoneal injection compared with free IMC. In addition, decreased uptake of loaded IMC in the liver and kidney compared to free IMC (p < 0.05) was detected. Furthermore, PVP-OD4000 nanoparticles loaded with IMC showed an enhanced anti-inflammatory effect compared to free IMC (p < 0.05) in carrageenan-induced and complete Freund’s adjuvant-induced−(CFA) sub-chronic and chronic paw edema treatment (p < 0.01; p < 0.01). Notably, upon oral administration of loaded IMC, animals had a significantly lower ulcer score and Paul’s Index (3.9) compared to the free drug (p < 0.05). The obtained results suggest that IMC loaded to PVP nanoparticles exhibit superior anti-inflammatory activity in vivo and a safe gastrointestinal profile and pose a therapeutic alternative for the currently available NSAIDs’ administration.

Nanofiber as a novel vehicle for transdermal delivery of therapeutic agents: challenges and opportunities

Background

Transdermal delivery of drugs is a quite challenging task for pharmaceutical scientists. The transdermal route is preferred over the oral route due to various advantages like avoidance of the first-pass effect, non-invasiveness, and high patient compliance. Therefore, it is necessary to develop an effective carrier system that enables the effective passage of the drug through the dermal barrier.

Main body of abstract

Various novel drug delivery systems are used to enhance the permeation of a variety of drugs through the skin barrier. Researchers around the globe have explored nanofibers for the transdermal delivery of various therapeutic agents. Nanofibers are designed to have a high concentration of therapeutic agents in them promoting their flux through various skin layers. Polymeric nanofibers can be explored for the loading of both hydrophilic and lipophilic drugs. Biopolymer-based nanofibers have been also explored for transdermal delivery. They are capable of controlling the release of therapeutic agents for a prolonged time.

Short conclusion

The literature presented in this review paper provides significant proof that nanofibers will have an intense impact on the transdermal delivery of different bioactive molecules in the future.

Graphic abstract

Optical Coherence Tomography and Microdialysis for Microneedle-Mediated Penetration Enhancement Study of Paeoniflorin-Loaded Ethosomes

BACKGROUND

To understand the cumulative effect of topical formulations after medication, evaluate the therapeutic effect of microneedle-assisted (MN-assisted) paeoniflorin-loaded ethosomes (TGP-E), and explore the potential for deep penetration of drugs, this paper uses microdialysis to systematically study the percutaneous pharmacokinetics of TGP-E.

METHODS

First, optical coherence tomography (OCT) was used to study the effectiveness of microneedle puncture. Second, a microdialysis method and a UPLC-MS method for determining the amount of paeoniflorin (Pae) in dialysate were established. Finally, the transdermal pharmacokinetics of TGP-E was studied using in vivo microdialysis in rats under the above MN-assisted conditions.

RESULTS

The optimal MN-assisted conditions were obtained at a microneedle length of 500 μm, a pressure of 3 N, and an action time of 3 min. The pharmacokinetic results demonstrated that the maximum drug concentration (Cmax) and the area under the curve (AUC) of the TGP-E gel were higher than the TGP-saline solution gel, and the mean retention time was lower. These indicated that microneedle can promote the entry of the ethosomes into the skin for in vivo experiments and greatly improve the possibility of deep penetration of the water-soluble Pae.

CONCLUSION

Therefore, the microneedle-ethosomes delivery system is a more ideal means for promoting the deep penetration of Pae. These findings may provide a reference for the combination of multiple penetration-enhancement ways to promote drug absorption, and also provide a new insight to realize the development of novel, safe, and more effective dosage forms and administration routes of drugs.

Skin Metabolomics

Skin retains numerous low-molecular-weight compounds (metabolites). Some of these compounds fulfill specific physiological roles, while others are by-products of metabolism. The skin surface can be sampled to detect and quantify skin metabolites related to diseases. Miniature probes have been developed to detect selected high-abundance metabolites secreted with sweat. To characterize a broad spectrum of skin metabolites, specimens are collected with one of several available methods, and the processed specimens are analyzed by chromatography, mass spectrometry (MS), or other techniques. Diseases for which skin-related biomarkers have been found include cystic fibrosis (CF), psoriasis, Parkinson's disease (PD), and lung cancer. To increase the clinical significance of skin metabolomics, it is desirable to verify correlations between metabolite levels in skin and other biological tissues/matrices.

New Delivery Route of Gambogic Acid Via Skin for Topical Targeted Therapy of Cutaneous Melanoma and Reduction of Systemic Toxicity

Cutaneous melanoma is the deadliest form of skin cancer, and gambogic acid (GA) exhibits potent anti-melanoma activity. However, clinical application of GA via intravenous injection and oral administration is limited by systemic toxicity and rapid metabolism in the blood. Here, we developed a new, topical route of GA delivery for anti-melanoma activity and reduction of systemic toxicity. The results indicated that the barrier of the stratum corneum (SC) and low diffusion of GA in the hydrophilic viable skin (epidermis and dermis) limited the GA penetration through intact skin. The combination of azone (AZ) and propylene glycol (PG) showed obvious synergistic effects on skin penetration by GA via improving the permeability of the SC and greatly increasing the skin accumulation of GA, thereby forming a high drug concentration in the skin and achieving a topical targeted treatment of melanoma. In addition, GA (AZ-PG) achieved the same anti-melanoma effect via topical delivery as via intravenous injection. Intravenous injection and oral administration of GA induced remarkable pathological changes in various organs in mice, whereas GA was not toxic to various organs or to the skin via topical delivery. These findings indicated that topical administration of GA is an alternative route for melanoma treatment.

Research progress and perspective in metabolism and metabolomics of psoriasis

ABSTRACT

Psoriasis is considered a systemic disease associated with metabolic abnormalities, and it is important to understand the mechanisms by which metabolism affects pathophysiological processes both holistically and systematically. Metabolites are closely related to disease phenotypes, especially in systemic diseases under multifactorial modulation. The emergence of metabolomics has provided information regarding metabolite changes in lesions and circulation and deepened our understanding of the association between metabolic reprogramming and psoriasis. Metabolomics has great potential for the development of effective biomarkers for clinical diagnosis, therapeutic monitoring, prediction of the efficacy of psoriasis management, and further discovery of new metabolism-based therapeutic targets.

Development of Topical/Transdermal Self-Emulsifying Drug Delivery Systems, Not as Simple as Expected

Self-emulsifying drug delivery systems (SEDDSs) originated as an oral lipid-based drug delivery system with the sole purpose of improving delivery of highly lipophilic drugs. However, the revolutionary drug delivery possibilities presented by these uniquely simplified systems in terms of muco-adhesiveness and zeta-potential changing capacity lead the way forward to ground-breaking research. Contrarily, SEDDSs destined for topical/transdermal drug delivery have received limited attention. Therefore, this review is focused at utilising principles, established during development of oral SEDDSs, and tailoring them to fit evaluation strategies for an optimised topical/transdermal drug delivery vehicle. This includes a detailed discussion of how the authentic pseudo-ternary phase diagram is employed to predict phase behaviour to find the self-emulsification region most suitable for formulating topical/transdermal SEDDSs. Additionally, special attention is given to the manner of characterising oral SEDDSs compared to topical/transdermal SEDDSs, since absorption within the gastrointestinal tract and the multi-layered nature of the skin are two completely diverse drug delivery territories. Despite the advantages of the topical/transdermal drug administration route, certain challenges such as the relatively undiscovered field of skin metabolomics as well as the obstacles of choosing excipients wisely to establish skin penetration enhancement might prevail. Therefore, development of topical/transdermal SEDDSs might be more complicated than expected.