Assessment of Transdermal Delivery of Topical Compounds in Skin Scarring Using a Novel Combined Approach of Raman Spectroscopy and High-Performance Liquid Chromatography

Rhamnose-PEG-induced supramolecular helices: Addressing challenges of drug solubility and release efficiency in transdermal patch

Transdermal drug delivery systems (TDDS) demand both high drug loading capacity and efficient delivery. In order to improve both simultaneously, this study aims to develop a novel rhamnose-induced pressure-sensitive adhesive (HPR) by dispersing the drug in the supramolecular helical structure. Ten model drugs, categorized as acidic and basic compounds, were chosen to understand the characteristics of the HPR and its inner mechanism. Notably, it enhanced drug loading by 1.41 to 5 times over commercially available pressure-sensitive adhesives Duro-Tak@ 87-4098 and Duro-Tak@ 87-2287, in addition to increasing drug release efficiency by a factor of about 5. Pharmacokinetic evaluation demonstrated that the HPR group had >4-fold (Tulobuterol TUL) and 3-fold (Diclofenac DIC) more area under the blood drug concentration curve (AUC) than the commercial TUL and DIC patches in the absence of added excipients and a significantly prolonged mean residence time (MRT) of >4-fold (TUL) and 3-fold (DIC), demonstrating the potential for highly efficacious and prolonged dosing. Furthermore, its safety and mechanical properties meet the requisite standards. Mechanistic inquiries unveiled that both acidic and basic drugs establish hydrogen bonds with HPR and become encapsulated within supramolecular helical structures. The supramolecular helical structures, significantly elevated both the enthalpy of the drug-HPR and entropy of the drugs release, thereby substantially enhancing drug delivery efficiency. In summary, HPR enabled a significant simultaneous enhancement of drug loading and drug delivery, which, together with its unique spatial structure, would contribute to the development of TDDS. In addition, the establishment of rhamnose-induced supramolecular helical structures would provide innovative pathways for different drug delivery systems.

Formulation Development and Molecular Mechanism Characterization of Long-Acting Patches of Asenapine for Efficient Delivery by Combining API-ILs Strategy and Controlled-Release Polymers

The objective of our study, which combined API-ILs strategy and controlled-release polymers, was to prepare a 72 h long-acting drug-in-adhesive patch for optimum delivery of asenapine (ASE). Special attention was paid to the permeation promotion mechanism and the controlled release behavior of ASE-ILs in pressure sensitive adhesives (PSA). Formulation factors were investigated by ex vivo transdermal experiments. The optimized patch was evaluated by pharmacokinetics study and skin irritation test. The obtained formulation was as follows, 15% w/w ASE-MA (about 1136 μg/cm2 ASE, 413 μg/cm2 MA), AACONH2 (Amide adhesive) as the matrix, 80 μm thickness, backing film of CoTran™ 9733. The optimized patch displayed satisfactory ex vivo and in vivo performance with Q 72 h of 620 ± 44 µg/cm2 and Fabs of 62.4%, which utilization rate (54.6%) was significantly higher than the control group (38.3%). By using the classical shake flask method, 13C NMR, DSC, and FTIR, the physicochemical properties and structure of ILs were characterized. log Do/w, ATR-FTIR, Raman, and molecular dynamics simulation results confirmed that ASE-MA (MA: 3-Methoxypropionic acid) had appropriate lipophilicity, and affected lipid fluidity as well as the conformation of keratin to improve the skin permeation. The FTIR, MDSC, rheology, and molecular docking results revealed that hydrogen bond (H-bond), were formed between ASE-MA and PSA, and the drug increased the molecular mobility of polymer chains. In summary, the 72 h long-acting patch of ASE was successfully prepared and it supplied a reference for the design of long-acting patches with ASE.

Skin scarring: Latest update on objective assessment and optimal management

Although skin scarring is considered by some to be a minor, unavoidable consequence in response to skin injury, for many patients, cosmetically unsightly scars may cause uncomfortable symptoms and loss of function plus significant psycho-social distress. Despite their high prevalence and commonality, defining skin scars and their optimal management has proven problematic. Therefore, a literature search to assess the current evidence-base for scarring treatment options was conducted, and only those deemed Levels of Evidence 1 or 2 were included. Understanding the spectrum of skin scarring in the first instance is imperative, and is mainly comprised of four distinct endotypes; Stretched (flat), Contracted, Atrophic, and Raised for which the acronym S.C.A.R. may be used. Traditionally, scar assessment and response to therapy has employed the use of subjective scar scales, although these are now being superseded by non-invasive, objective and quantitative measurement devices. Treatment options will vary depending on the specific scar endotype, but fall under one of 3 main categories: (1) Leave alone, (2) Non-invasive, (3) Invasive management. Non-invasive (mostly topical) management of skin scarring remains the most accessible, as many formulations are over-the-counter, and include silicone-based, onion extract-based, and green tea-based, however out of the 52 studies identified, only 28 had statistically significant positive outcomes. Invasive treatment options includes intralesional injections with steroids, 5-FU, PDT, and laser with surgical scar excision as a last resort especially in keloid scar management unless combined with an appropriate adjuvant therapy. In summary, scar management is a rapidly changing field with an unmet need to date for a structured and validated approach.