A Rhamnose-PEG-Modified Dendritic Polymer for Long-Term Efficient Transdermal Drug Delivery

Development and adhesion evaluation of transdermal rotigotine patches utilizing 3D-printed skin-mimicking substrate, solid-state NMR, and ATR-FTIR techniques

Transdermal rotigotine patches, used to treat parkinson's disease, often face challenges in maintaining adequate adhesion, which is crucial for effective drug delivery. Adhesion performance is influenced by environmental conditions such as humidity and temperature, as well as skin characteristics like wrinkles and micro-delaminations that vary with age and sex. Standard adhesion tests using stainless steel (SS) substrates do not accurately mimic human skin, leading to overestimated adhesion strength. This study developed rotigotine matrix transdermal formulations with silicone pressure sensitive adhesive (PSA) and evaluated their adhesion properties at 32 ± 1°C and 75 ± 5 % RH in a stability chamber. Moisture uptake over 24 h was measured using solid-state nuclear magnetic resonance (SSNMR) spectroscopy and attenuated total reflectance-fourier transform infrared- (ATR-FTIR) spectroscopy. Adhesion tests, including probe tack and peel, were performed on SS and 3D-printed acrylonitrile butadiene styrene (ABS) substrates designed with micro-delaminations and wrinkles to simulate skin conditions. In vitro permeation testing (IVPT) studies demonstrated a flux of 10.48 ± 0.61 and 10.03 ± 0.57 μg/h/cm2 for formulations with and without mannitol, respectively. SSNMR and ATR-FTIR revealed significant moisture uptake, contributing to adhesion loss. Adhesion forces were significantly lower on ABS compared to SS, with further reductions observed on wrinkled and micro-delaminated surfaces, indicating that SS substrates overestimate adhesion results. This is the first study to combine SSNMR and skin-mimetic substrates for analyzing adhesion loss in transdermal patches, highlighting the potential of moisture-resistant agents like mannitol to enhance patch performance.

Bioinspired Suction-Driven Strategies with Nanoscale Skin-Controllable Adhesive Architectures for Efficient Liquid Formulated Transdermal Patches

For highly efficient and precise drug release, transdermal drug delivery systems (TDDS) have recently evolved through the combination of intelligent material-based structures with various active components. These strategies are an effort to overcome the significant difficulties in delivering large molecule drugs and nanomaterials due to the physical barrier of the skin, especially the stratum corneum, in traditional TDDS. Interestingly, multiscale suction-driven architectures (SDAs) inspired by bioinspired suction adhesion mechanisms have provided innovative solutions to these challenges. These architectures employ negative pressure to enhance nanoscale skin-controllable skin adhesion, temporarily bypass the skin barrier, and facilitate deep penetration of therapeutic agents, thereby, achieving the goals of increasing drug delivery efficiency and maximizing user convenience as a minimal invasive, needle-free platform. This review provides a comprehensive overview of suction-driven transdermal patches and emphasizes their integration with multifunctional materials to achieve stable adhesion and controlled drug release. Next, we present cost-effective and user-friendly suction-driven drug delivery patch devices through optimization of cupping structures without the incorporation of additional devices. Furthermore, we present cost-effective and user-friendly transdermal drug delivery patch devices that optimize multiscale cupping architectures without the need for additional devices. Potential of bioinspired SDAs in localized and systemic drug delivery through challenging and complex skin, as well as future perspectives, are discussed, along with innovative directions for more efficient and patient-centric transdermal drug delivery solutions.

Transdermal patch based on pressure-sensitive adhesive: the importance of adhesion for efficient drug delivery

INTRODUCTION

Transdermal patches offer a unique advantage by providing extended therapeutic benefits while maintaining stable plasma drug concentration. The efficacy and safety of patches depend significantly on their ability to adhere to the skin, a feature influenced by various external and internal factors.

AREAS COVERED

The review primarily focuses on the fundamental aspects of adhesion in transdermal patches, including basic information about the skin, the underlying principles of adhesion, drug delivery, and adhesion characteristics of pressure sensitive adhesives (PSAs), adhesion issues, impact factors, strategies to improve patch adhesion, and relevant molecular mechanisms.

EXPERT OPINION

The development of transdermal patches with sufficient adhesion for consistent and extended drug delivery remains a challenging task. Challenges in adhesion stem from the complex interplay among PSAs, permeation enhancers, active pharmaceutical ingredients (APIs), and other excipients in current patch compositions, further complicated by variations arising from dermatological factors. These intricacies significantly impede the consistent effectiveness of patches. Progress in the exploration of new PSA polymers, in conjunction with innovative patch compositions, is crucial for establishing an optimal equilibrium between drug utilization rate, drug-loading, drug release, and adhesion, thus effectively addressing the challenges related to adhesion.

Isosorbide-Based Acrylic Pressure-Sensitive Adhesives Through UV-Cured Crosslinking with a Balance Between Adhesion and Cohesion

The development of sustainable pressure-sensitive adhesives (PSAs) from natural biomass resources has attracted increasing attention owing to their non-toxic, biocompatible, and biodegradable features. In this study, a bio-based acrylic PSA with tunable adhesion and cohesion was synthesized by a selective chemical modification of isosorbide-5-acrylate (IA) and its copolymerization with butyl acrylate and acrylic acid through UV-curing crosslinking. During the UV-curing process, the synthesized isosorbide diacrylate ester (IDAE) served as the crosslinker, effectively improving the crosslinking degree of PSA. The impact of IA and IDAE on the mechanical properties of PSA was studied. Moreover, to achieve a balance between adhesion and cohesion, the optimal composition was identified. The addition of IA significantly enhances the stiffness of PSA. Furthermore, the combined effect of IA and IDAE improves the overall adhesion properties of the PSA. The optimal bio-based PSA demonstrates a peel force of 13.9 N/25 mm and a persistent time of 6820 min, promising to replace traditional petroleum-based PSAs.

Nanocarrier-Based Transdermal Drug Delivery Systems for Dermatological Therapy

Dermatoses are among the most prevalent non-fatal conditions worldwide. Given this context, it is imperative to introduce safe and effective dermatological treatments to address the diverse needs and concerns of individuals. Transdermal delivery technology offers a promising alternative compared to traditional administration methods such as oral or injection routes. Therefore, this review focuses on the recent achievements of nanocarrier-based transdermal delivery technology for dermatological therapy, which summarizes diverse delivery strategies to enhance skin penetration using various nanocarriers including vesicular nanocarriers, lipid-based nanocarriers, emulsion-based nanocarriers, and polymeric nanocarrier according to the pathogenesis of common dermatoses. The fundamentals of transdermal delivery including skin physiology structure and routes of penetration are introduced. Moreover, mechanisms to enhance skin penetration due to the utilization of nanocarriers such as skin hydration, system deformability, disruption of the stratum corneum, surface charge, and tunable particle size are outlined as well.

A strong, silk protein-inspired tissue adhesive with an enhanced drug release mechanism for transdermal drug delivery

In transdermal drug delivery system (TDDS) patches, achieving prolonged adhesion, high drug loading, and rapid drug release simultaneously presented a significant challenge. In this study, a PHT-SP-Cu2+ adhesive was synthesized using polyethylene glycol (PEG), hexamethylene diisocyanate (HDI), trimethylolpropane (TMP), and silk protein (SP) as functional monomers which were combined with Cu2+ to improve the adhesion, drug loading, and drug release of the patch. The structure of the adhesion chains and the formation of Cu2+-p-π conjugated network in PHT-SP-Cu2+ were characterized and elucidated using different characterization methods including FT-IR, 13C NMR, XPS, SEM imaging and thermodynamic evaluation. The formulation of pressure-sensitive adhesive (PSA) was optimized through comprehensive research on adhesion, mechanics, rheology, and surface energy. The formulation of 3 wt.% SP and 3 wt.% Cu2+ provided superior adhesion properties compared to commercial standards. Subsequently, the peel strength of PHT-SP-Cu2+ was 7.6 times higher than that of the commercially available adhesive DURO-TAK® 87-4098 in the porcine skin peel test. The adhesion test on human skin confirmed that PHT-SP-Cu2+ could adhere to the human body for more than six days. Moreover, the drug loading, in vitro release test and skin permeation test were investigated using ketoprofen as a model drug, and the results showed that PHT-SP-Cu2+ had the efficacy of improving drug compatibility, promoting drug release and enhancing skin permeation as a TDDS. Among them, the drug loading of PHT-SP-Cu2+ was increased by 6.25-fold compared with PHT, and in the in vivo pharmacokinetic analysis, the AUC was similarly increased by 19.22-fold. The mechanism of α-helix facilitated drug release was demonstrated by Flori-Hawkins interaction parameters, molecular dynamics simulations and FT-IR. Biosafety evaluations highlighted the superior skin cytocompatibility and safety of PHT-SP-Cu2+ for transdermal applications. These results would contribute to the development of TDDS patch adhesives with outstanding adhesion, drug loading and release efficiency. STATEMENT OF SIGNIFICANCE: A new adhesive, PHT-SP-Cu2+, was created for transdermal drug delivery patches. Polyethylene glycol, hexamethylene diisocyanate, trimethylolpropane, silk protein, and Cu2+ were used in synthesis. Characterization techniques confirmed the structure and Cu2+-p-π conjugated networks. Optimal formulation included 3 wt.% SP and 3 wt.% Cu2+, exhibiting superior adhesion. PHT-SP-Cu2+ showed 7.6 times higher peel strength than DURO-TAK® 87-4098 on porcine skin and adhered to human skin for over six days. It demonstrated a 6.25-fold increase in drug loading compared to PHT, with 19.22-fold higher AUC in vivo studies. α-helix facilitated drug release, proven by various analyses. PHT-SP-Cu2+ showed excellent cytocompatibility and safety for transdermal applications. This study contributes to developing efficient TDDS patches.