A Mechanistic Study to Determine the Structural Similarities Between Artificial Membrane Strat-M™ and Biological Membranes and Its Application to Carry Out Skin Permeation Study of Amphotericin B Nanoformulations

Fabrication and evaluation of nanoemulsion based insulin loaded microneedles for transdermal drug delivery

Aim: Insulin therapy require self-administration of subcutaneous injection leading to painful and inconvenient drug therapy. The aim is to fabricate nanoemulsion (NE) based insulin loaded microneedles with improved bioavailability and patient compliance. Materials & methods: Different ratios of polyvinyl alcohol and polyvinylpyrrolidone as polymers were prepared through micro-molding technique for microneedles. Characterization of were performed using scanning electron microscope, differential scanning calorimetry, Fourier-transform infrared spectroscopy and circular dichroism. Mechanical strength, hygroscopicity and pain perception of these microneedles were also evaluated. In vitro release, permeation and in vivo PK/PD study of NE-based microneedles were conducted. Results: NE-based microneedles of insulin have improved bioavailability and quick response. Conclusion: Microneedles loaded with insulin can be effectively delivered insulin transdermally to treat diabetes with increased convenience and patient compliance.

Leveraging 3D-printed microfluidic micromixers for the continuous manufacture of melatonin loaded SNEDDS with enhanced antioxidant activity and skin permeability

Vesicants are chemical warfare agents (CWAs) capable of causing severe skin damage and systemic toxicity. Melatonin, known for its anti-inflammatory and antioxidant properties, can mitigate the effects of these agents. Self-nano-emulsifying drug delivery systems (SNEDDS) containing a high melatonin concentration (5 %, 50 mg/g) were optimized using a quality-by-design approach from biocompatible, non-irritant excipients with a particle size of about 100 nm. The melatonin-loaded SNEDDS showed a 43-fold greater permeability than a conventional melatonin cream. Chemical stability at ambient temperature (25 °C) was maintained for one year. The preparation of optimised melatonin-loaded SNEDDS using a simple mixing method was compared to microfluidic micromixers. Mixing was successfully achieved using a 3D-printed (fused deposition modeling or stereolithography) T-shaped toroidal microfluidic chip (with a channel geometry optimized by computational fluid dynamics), resulting in a scalable, continuous process for the first time with a substantial reduction in preparation time compared to other conventional mixing approaches. No statistically significant differences were observed in the key quality attributes, such as particle size and melatonin loading, between the conventional mixing method in a water bath to reach equilibrium solubility and the use of 3D-printed micromixers. This scalable, continuous, cost-effective approach improves the overall efficiency of SNEDDS production, reduces the cost of quality control for multiple batches, and demonstrates the potential of microfluidic manufacturing with readily customizable 3D-printed micromixers at points of care such as military bases.

Asiatic acid-entrapped transfersomes for the treatment of hypertrophic scars: In vitro appraisal, bioactivity evaluation, and clinical study

Non-invasive treatment options for hypertrophic scars (HTS) are limited, and treating HTS remains challenging due to their unappealing appearance and associated social stigma. In this work, a novel transfersomal system named Asiatic acid-entrapped transfersomes (AATs) was prepared. AATs were evaluated for their skin permeability, anti-inflammatory activity, and other characteristic parameters to determine the most promising formulation. Asiatic acid-entrapped transfersomal gel (AATG), which was obtained by incorporating the lead AATs in a gel base, underwent testing in an 8-week, double-blind, placebo-controlled, split-skin clinical study. The net skin elasticity (R5), melanin index (MI), and skin surface hydration were analyzed employing Cutometer®, Mexameter®, and Corneometer®, respectively, in order to evaluate the effectiveness of the developed AATG. AATs exhibited vesicular sizes and zeta potential values within the range of (27.15 ± 0.95 to 63.54 ± 2.51 nm) and (-0.010 to -0.129 mV), respectively. TW80AAT gave the highest %EE (90.84 ± 2.99%), deformability index (101.70 ± 11.59 mgs-1), permeation flux at 8 h (0.146 ± 0.005 mg/cm2/h), and anti-inflammatory activity (71.65 ± 1.83%). The clinical study results of AATG indicated no adverse skin reactions. Furthermore, product efficacy tests demonstrated a significant reduction in MI and an increase in net skin elasticity at 2, 4, and 8 weeks. These pilot study outcomes support the effectiveness of the AATG.

Development of a tadalafil transdermal formulation and evaluation of its ability to in vitro transdermal permeate using Strat-M® membrane

Tadalafil (TDF) has low water solubility, high intestinal permeability and belongs to the Biopharmaceutics Classification System (BCS) Class II. Due to high intestinal permeability, only oral administration (tablets) and oral thin film formulations have been developed. Therefore, it is necessary to develop various formulations, such as external formulations and transdermal absorption formulations requested by patients. The purpose of this study is to improve the solubility and skin permeability of TDF, and to develop a novel transdermal formulation with secured stability over time. The research strategy is to determine solvents that will improve TDF solubility and to screen substances that will enhance TDF permeability. Skin penetration tests were simulated by using a Strat-M® membrane in Franz diffusion cell systems. The optimal formulation (F1, consisting of TDF/HDTMA-Br at a ratio of 1:10 [weight/weight] in DPG) observed the highest permeability compared to all formulations in PBS (pH 7.4). Changes in thermal property of F1 formulation was observed and maintained its stability over 12 months including drug content (μg/mL), appearance, pH, and permeation (μg/cm2). In conclusion, DPG played a supported role in improving both TDF solubilization and permeability, whereas HDTMA-Br played a key role in enhancing permeability. It is thought that these results will be supplemented in the future to conduct research and experiments on humans.

Methods for the characterisation of dermal uptake: Progress and perspectives for organophosphate esters

Organophosphate esters (OPEs) are a group of pollutants that are widely detected in the environment at high concentrations. They can adversely affect human health through multiple routes of exposure, including dermal uptake. Although attention has been paid to achieving an accurate and complete quantification of the dermal uptake of OPEs, existing evaluation methods and parameters have obvious weaknesses. This study reviewed two main categories of methodologies, namely the relative absorption (RA) model and the permeability coefficient (PC) model, which are widely used to assess the dermal uptake of OPEs. Although the PC model is more accurate and is increasingly used, the most important parameter in this model, the permeability coefficient (Kp), has been poorly characterised for OPEs, resulting in considerable errors in the estimation of the dermal uptake of OPEs. Thus, the detailed in vitro methods for the determination of Kp are summarised and sorted. Furthermore, the commonly used skin membranes are identified and the factors affecting Kp and corresponding mechanisms are discussed. In addition, the experimental conditions, conclusions, and available data on Kp values of the OPEs are thoroughly summarised. Finally, the corresponding knowledge gaps are proposed, and a more accurate and sophisticated experimental system and unknown Kp values for OPEs are suggested.

Liposome-assisted penetration and antiaging effects of collagen in a 3D skin model

BACKGROUND

Collagen is a major component of the extracellular matrix that supports the epidermal layers of the skin; thus, many strategies have been made to enhance the topical delivery of collagen for antiaging purposes. In addition, our previous study indicated that liposome can help the penetration of active ingredients into the skin.

AIMS

To produce stable collagen-encapsulated liposomes to improve the topical delivery of collagen.

METHODS

Collagen-encapsulated liposomes were fabricated using high-pressure homogenization method. The colloidal stability and adhesion ability were confirmed using dynamic light scattering, and spectrofluorophotometer, respectively. Keratinocyte differentiations of 3D skin before and after treatment with collagen-encapsulated liposomes were confirmed by real-time PCR.

RESULTS

In comparison with native collagen, collagen-encapsulated liposomes enhanced collagen retention in artificial membranes by twofold, even after repeated washings with water. In addition, real-time PCR results indicated that 3D skin treated with collagen-encapsulated liposomes exhibited higher levels of collagen, keratin, and involucrin, even after ethanol treatment.

CONCLUSION

Liposomes could serve as efficient delivery vehicles for collagen, thereby enhancing its antiaging effects.

Strat-M® positioning for skin permeation studies: A comparative study including EpiSkin® RHE, and human skin

In the development and optimization of dermatological products, In Vitro Permeation Testing (IVPT) is pivotal for controlled study of skin penetration. To enhance standardization and replicate human skin properties reconstructed human skin and synthetic membranes are explored as alternatives. Strat-M® is a membrane designed to mimic the multi-layered structure of human skin for IVPT. For instance, in Strat-M®, the steady-state fluxes (JSS) of resorcinol in formulations free of permeation enhancers were found to be 41 ± 5 µg/cm2·h for the aqueous solution, 42 ± 6 µg/cm2·h for the hydrogel, and 40 ± 6 µg/cm2·h for the oil-in-water emulsion. These results were closer to excised human skin (5 ± 3, 9 ± 2, 13 ± 6 µg/cm2·h) and surpassed the performance of EpiSkin® RHE (138 ± 5, 142 ± 6, and 162 ± 11 µg/cm2·h). While mass spectrometry and Raman microscopy demonstrated the qualitative molecular similarity of EpiSkin® RHE to human skin, it was the porous and hydrophobic polymer nature of Strat-M® that more faithfully reproduced the skin's diffusion-limiting barrier. Further validation through similarity factor analysis (∼80-85%) underscored Strat-M®'s significance as a reliable substitute for human skin, offering a promising approach to enhance realism and reproducibility in dermatological product development.

Innovative Topical Patches for Non-Melanoma Skin Cancer: Current Challenges and Key Formulation Considerations

Non-melanoma skin cancer (NMSC) is the most prevalent malignancy worldwide, with approximately 6.3 million new cases worldwide in 2019. One of the key management strategies for NMSC is a topical treatment usually utilised for localised and early-stage disease owing to its non-invasive nature. However, the efficacy of topical agents is often hindered by poor drug penetration and patient adherence. Therefore, various research groups have employed advanced drug delivery systems, including topical patches to overcome the problem of conventional topical treatments. This review begins with an overview of NMSC as well as the current landscape of topical treatments for NMSC, specifically focusing on the emerging technology of topical patches. A detailed discussion of their potential to overcome the limitations of existing therapies will then follow. Most importantly, to the best of our knowledge, this work unprecedentedly combines and discusses all the current advancements in innovative topical patches for the treatment of NMSC. In addition to this, the authors present our insights into the key considerations and emerging trends in the construction of these advanced topical patches. This review is meant for researchers and clinicians to consider utilising advanced topical patch systems in research and clinical trials toward localised interventions of NMSC.

Hydrogel Formulations for Topical Insulin Application: Preparation, Characterization and In Vitro Permeation across the Strat-M® Membrane

Insulin has shown efficacy in the treatment of hard-to-heal wounds, which is mainly due to its role in regulating oxidative stress and inflammatory reactions. The aim of this study was to develop an insulin-hydrogel carrier based on Sepineo™ P 600 and Sepineo™ PHD 100 for application to lesional skin. Preformulation studies of the developed formulations were performed in terms of analysis of the pharmaceutical availability of insulin from the hydrogels through the Strat-M® membrane, and rheological and texture measurements. Insulin is released in a prolonged manner; after a time of 6.5 h, 4.01 IU/cm2 (53.36%) and 3.69 IU/cm2 (47.4%) of the hormone were released from the hydrogel based on Sepineo™ P 600 and Sepineo™ PHD 100, respectively. Rheological analysis showed that the hydrogels tested belong to non-Newtonian, shear-thinning systems with yield stress. The insulin-hydrogel based on Sepineo™ P 600 and Sepineo™ PHD 100 shows optimal application properties. The results obtained provide a basis for further preclinical and clinical studies.

Assessment of anti-psoriatic activity of bakuchiol-loaded solid lipid nanoparticles-based gel: design, characterization, and mechanistic insight via NF-kB signaling pathway

The aim of the current study is to evaluate the anti-psoriatic potential of bakuchiol (Bak) loaded solid lipid nanoparticles (SLNs) via modulating inflammatory and oxidative pathways. Bak-loaded SLNs were prepared using hot homogenization method and characterized by various spectroscopic techniques. Bak-SLNs suspension was formulated into gel using Carbopol. Different in vivo assays were executed to explore the role of inflammatory markers and oxidative enzymes in psoriasis. DLS (dynamic light scattering) analysis showed suitable particle size, zeta potential, and polydispersity index (PDI) of developed formulation. TEM (transmission electron microscopy) reveal the spherical shape of Bak-SLNs particles. The release studies confirmed the sustained release of Bak-SLNs-based gel. UV-B-induced psoriatic Wistar rat model showed significant anti-psoriatic effect of Bak via regulating inflammatory markers (NF-kB, IL-6, IL-4, and IL-10) and levels of anti-oxidant enzymes, superoxide dismutase (SOD), catalase (CAT), glutathione (GSH), and glutathione-S-transferase (GST). Furthermore, RT-qPCR analysis confirms that Bak downregulates the expression of inflammatory markers, while histology and immunohistology results also confirm the anti-psoriatic effect of Bak. The study indicates that Bak-loaded SLNs-based gel significantly downregulates the level of cytokines and interleukins involve in NF-kB signaling cascade; hence, it can prove to be a novel therapeutic approach to cure psoriasis.

Skin models of cutaneous toxicity, transdermal transport and wound repair

Skin is widely used as a drug delivery route due to its easy access and the possibility of using relatively painless methods for the administration of bioactive molecules. However, the barrier properties of the skin, along with its multilayer structure, impose severe restrictions on drug transport and bioavailability. Thus, bioengineered models aimed at emulating the skin have been developed not only for optimizing the transdermal transport of different drugs and testing the safety and toxicity of substances but also for understanding the biological processes behind skin wounds. Even though in vivo research is often preferred to study biological processes involving the skin, in vitro and ex vivo strategies have been gaining increasing relevance in recent years. Indeed, there is a noticeably increasing adoption of in vitro and ex vivo methods by internationally accepted guidelines. Furthermore, microfluidic organ-on-a-chip devices are nowadays emerging as valuable tools for functional and behavioural skin emulation. Challenges in miniaturization, automation and reliability still need to be addressed in order to create skin models that can predict skin behaviour in a robust, high-throughput manner, while being compliant with regulatory issues, standards and guidelines. In this review, skin models for transdermal transport, wound repair and cutaneous toxicity will be discussed with a focus on high-throughput strategies. Novel microfluidic strategies driven by advancements in microfabrication technologies will also be revised as a way to improve the efficiency of existing models, both in terms of complexity and throughput.

Development and evaluation of niacinamide transdermal formulation by artificial membrane permeability

Despite many efforts to improve the transdermal permeability of drugs, most of them are blocked by the skin barrier. Niacinamide (NAC) is a Biopharmaceutics Classification System class I drug with high aqueous solubility and intestinal permeability. Due to the high solubility and intestinal permeability of NAC, the development of new formulations is insufficient as transdermal, injection etc. Thus, this study aimed to develop the novel NAC formulation with improved skin permeability and secured stability. The NAC formulation approach is to first select a solvent that improves skin permeability, and then select a second penetration enhancer to determine the final formulation. All formulations were evaluated for skin permeability using an artificial membrane (Strat-M®). The optimal formulation (non-ionic formulations (NF1) consisted of NAC/Tween®80 = 1:1 wt ratio in dipropylene glycol [DPG]) showed the highest permeability in all formulations in PBS buffer (pH 7.4). The thermal properties of NF1 were altered. Moreover, NF1 maintained a stable drug content, appearance, and pH value for 12 months. In conclusion, DPG had an excellent effect in increasing the NAC permeation, and Tween®80 played a boosting role. Through this study, an innovative NAC formulation was developed, and good results are expected for human transdermal research.

Innovative Rocuronium Bromide Topical Formulation for Targeted Skin Drug Delivery: Design, Comprehensive Characterization, In Vitro 2D/3D Human Cell Culture and Permeation

Cutaneous squamous cell carcinoma (cSCC) is the second-most common type of non-melanoma skin cancer and is linked to long-term exposure to ultraviolet (UV) radiation from the sun. Rocuronium bromide (RocBr) is an FDA-approved drug that targets p53-related protein kinase (PRPK) that inhibits the development of UV-induced cSCC. This study aimed to investigate the physicochemical properties and in vitro behavior of RocBr. Techniques such as thermal analysis, electron microscopy, spectroscopy and in vitro assays were used to characterize RocBr. A topical oil/water emulsion lotion formulation of RocBr was successfully developed and evaluated. The in vitro permeation behavior of RocBr from its lotion formulation was quantified with Strat-M^® synthetic biomimetic membrane and EpiDerm™ 3D human skin tissue. Significant membrane retention of RocBr drug was evident and more retention was obtained with the lotion formulation compared with the solution. This is the first systematic and comprehensive study to report these findings.

Preparation and Evaluation of Vitamin D3 Supplementation as Transdermal Film-Forming Solution

Vitamin D3 is available in oral and injectable dosage forms. Interest in the transdermal route as an alternative to the oral and parenteral routes has grown recently. In this study, several film-forming solutions for the transdermal delivery of vitamin D3 were prepared. They contained 6000 IU/mL of vitamin D3 that formed a dry and acceptable film in less than 5 min after application. The formulations consisted of ethanol and acetone 80:20, and one or more of the following ingredients: Eudragit L100-55, PVP, PG, limonene, oleic acid, camphor, and menthol. Vitamin D3 release was studied from both the film-forming solution and pre-dried films using a Franz diffusion cell. The film-forming solution released a significant amount of vitamin D3 compared to the dry film, which is attributed mostly to the saturation driving force due to the evaporation of volatile solvents. In vitro permeation studies through artificial skin Strat M^® membrane revealed that the cumulative amount of vitamin D3 permeated after 24 h under the experimental conditions was around 800 IU across 3.14 cm². The cumulative permeation curve showed faster permeation in earlier stages. Young's modulus, viscosity, and pH of the formulations were determined. Most of the formulations were stable for 3 weeks.

Repellent active ingredients encapsulated in polymeric nanoparticles: potential alternative formulations to control arboviruses

Dengue, yellow fever, Chinkungunya, Zika virus, and West Nile fever have infected millions and killed a considerable number of humans since their emergence. These arboviruses are transmitted by mosquito bites and topical chemical repellents are the most commonly used method to protect against vector arthropod species. This study aimed to develop a new generation of repellent formulations to promote improved arboviruses transmission control. A repellent system based on polycaprolactone (PCL)-polymeric nanoparticles was developed for the dual encapsulation of IR3535 and geraniol and further incorporation into a thermosensitive hydrogel. The physicochemical and morphological parameters of the prepared formulations were evaluated by dynamic light scattering (DLS), nano tracking analysis (NTA), atomic force microscopy (AFM). In vitro release mechanisms and permeation performance were evaluated before and after nanoparticles incorporation into the hydrogels. FTIR analysis was performed to evaluate the effect of formulation epidermal contact. Potential cytotoxicity was evaluated using the MTT reduction test and disc diffusion methods. The nanoparticle formulations were stable over 120 days with encapsulation efficiency (EE) of 60% and 99% for IR3535 and geraniol, respectively. AFM analysis revealed a spherical nanoparticle morphology. After 24 h, 7 ± 0.1% and 83 ± 2% of the GRL and IR3535, respectively, were released while the same formulation incorporated in poloxamer 407 hydrogel released 11 ± 0.9% and 29 ± 3% of the loaded GRL and IR3535, respectively. GRL permeation from PCL nanoparticles and PCL nanoparticles in the hydrogel showed similar profiles, while IR3535 permeation was modulated by formulation compositions. Differences in IR3535 permeated amounts were higher for PCL nanoparticles in the hydrogels (36.9 ± 1.1 mg/cm²) compared to the IR3535-PCL nanoparticles (29.2 ± 1.5 mg/cm²). However, both active permeation concentrations were low at 24 h, indicating that the formulations (PCL nanoparticles and PCL in hydrogel) controlled the bioactive percutaneous absorption. Minor changes in the stratum corneum (SC) caused by interaction with the formulations may not represent a consumer safety risk. The cytotoxicity results presented herein indicate the carrier systems based on poly-epsilon caprolactone (PCL) exhibited a reduced toxic effect when compared to emulsions, opening perspectives for these systems to be used as a tool to prolong protection times with lower active repellent concentrations.

Determination of Alteration in Micromeritic Properties of a Solid Dispersion: Brunauer-Emmett-Teller Based Adsorption and Other Structured Approaches

The present study is focused on the use of solid dispersion technology to triumph over the solubility-related problems of bexarotene which is currently used for treating various types of cancer and has shown potential inhibitory action on COVID-19 main protease and human ACE2 receptors. It is based on comparison of green locust bean gum and synthetic poloxamer as polymers using extensive mechanistic methods to explore the mechanism behind solubility enhancement and to find suitable concentration of drug to polymer ratio to prepare porous 3^rd generation solid dispersion. The prepared solid dispersions were characterized using different studies like X-ray diffraction (XRD), thermal gravimetric analysis (TGA), scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET), differential scanning calorimetry (DSC), and particle size analysis in order to determine the exact changes occurred in the product which are responsible for enhancing solubility profiles of an insoluble drug. The results showed different profiles for particle size, solubility, dissolution rate, porosity, BET, and Langmuir specific surface area of prepared solid dispersions by using different polymers. In addition to the comparison of polymers, the BET analysis deeply explored the changes occurred in all dispersions when the concentration of polymer was increased. The optimized solid dispersion prepared with MLBG using lyophilization technique showed reduced particle size of 745.7±4.4 nm, utmost solubility of 63.97%, pore size of 211.597 Å, BET and Langmuir specific surface area of 5.6413 m²/g and 8.2757 m²/g, respectively.

Enhancement of the Transdermal Delivery of Nonsteroidal Anti-inflammatory Drugs Using Liposomes Containing Cationic Surfactants

New hybrid liposomes based on cationic amphiphiles with different structures of the head group (cetyltrimethylammonium bromide (CTAB), 3-hexadecyl-1-hydroxyethylimidazolium bromide (IA-16(OH)), 1-(butylcarbamoyl)oxyethyl-3-hexadecylimidazolium bromide (IAC 16(Bu)), and hexadecylmethylpyrrolidinium bromide (PR-16)) were developed for transdermal administration of nonsteroidal anti-inflammatory drugs. The different surfactant/lipid compositions were studied to obtain stable liposomes with high functionality. The hydrodynamic diameter of cationic liposomes was ∼110 nm. An admixture of cationic surfactants and PC liposomes improves the physicochemical properties of vesicles and transdermal diffusion rate and prolongs the release of drugs. Liposomal diclofenac sodium (DS) and ketoprofen (KP) were tested (using Franz cells) for transdermal penetration. Drug diffusion monitoring for 48 h demonstrated that the maximum DS and KP penetration through the synthetic membranes (Strat-M) is characterized by values of 255 ± 2 and 186 ± 3 μg/cm², respectively. The influence of the surfactant head group on the properties (stability, release profile, permeability) of cationic liposomes was shown for the first time. While the drug specificity is evident for the rate of release, the permeability increases as follows: conventional liposomes < CTAB/PC < PR-16/PC < IAC-16(Bu)/PC < IA-16(OH)/PC for both medicines. The rat paw edema model was used to assess the anti-inflammatory effect of the IA-16(OH)/PC leader formulation in vivo. It was found that liposomal DS and KP are effective for relieving rat paw edema. It should be noted that DS-loaded hybrid liposomes demonstrated the highest therapeutic efficacy compared to conventional vesicles.

Preparation and Optimization of an Ultraflexible Liposomal Gel for Lidocaine Transdermal Delivery

The pain caused by lidocaine injections into the face prior to facial plastic surgeries intended to remove growths or tumorous lesions has been reported by many patients to be the worst part of these procedures. However, the lidocaine gels and creams currently on the market do not deliver an equal or better local anesthetic effect to replace these injections. To develop an alternative to the painful local anesthetic injection, we prepared ultraflexible liposomes using soy phosphatidylcholine, lidocaine, and different amounts of sodium cholate, a surfactant. The prepared ultraflexible liposomes (UFLs) were examined for particle size, zeta potential, cytotoxicity, and in vitro release. By using a carbomer as a gelling agent, the prepared UFL lidocaine gels were evaluated for their penetration ability in a Franz diffusion cell, using Strat-M membranes. The formulation achieving the highest amount of penetrated lidocaine was chosen for further pH, viscosity, and stability tests. The local anesthetic efficacy of the formulation was investigated by an in vivo tail-flick test in rats. Our findings suggested that this topical gel formulated with ultraflexible liposomal lidocaine has enhanced skin permeation ability, as well as an improved local analgesic effect from the lidocaine.

Novel Hyaluronic Acid ethosomes based gel formulation for topical use with reduced toxicity, better skin permeation, deposition, and improved pharmacodynamics

Hyaluronic Acid (HA) has been applied as an anti-ageing molecule in the form of topical products. Current topical commercial formulations of HA face the limitations of very small and stagnant skin permeation, thereby demanding enduring administration of the formulation to sustain its action. In this study, Lipid-based nanocarriers in the form of ethosomes were formulated in a 1% w/w HA strength and were extensively evaluated in vitro, ex-vivo, and in vivo parameters along with a comparison to it's commercial counterpart. The optimised ethosomes-based HA gel formulation revealed required pH (6.9 ± 0.2), small globule size (1024 ± 9 nm), zeta potential of -6.39 ± 0.2 mV, and 98 ± 1.1% HA content. The ex vivo skin permeation and deposition potenwere conferred on synthetic membrane Strat-M, Human cadaver skin, mice skin, rat skin, and pig skin, and both parameters were found to be much higher in comparison to the commercial topical formulation. Skin deposition capacity of the optimised HA formulation was further confirmed by Scan Electron Microscopy (SEM) and Confocal Laser Scanning Microscopy (CLSM) and it was observed that the developed ethosomal gel formulation got deposited more on the treated skin. The in vivo anti-ageing effect of optimised ethosomal gel on rats was found to be greater when compared to commercial formulation of HA and the developed carrier-based system proved to deliver the HA molecule in very small amounts into the systemic circulation. The results endorse the ethosomal carrier-based formulation of HA as a attractive technique for better local bioavailability of HA.

Determination of the Dissolution/Permeation and Apparent Solubility for Microencapsulated Emamectin Benzoate Using In Vitro and Ex Vivo Salmo salar Intestine Membranes

In this work, two microencapsulation techniques were used to protect and improve the absorption of emamectin benzoate (EB), which is an antiparasitic drug used to control Caligus rogercresseyi. EB has a low aqueous solubility, which affects its absorption in the intestine of Salmo salar. Microparticles were produced by spray drying and ionic gelation, using Soluplus® (EB−SOL) and sodium alginate (EB−ALG) as polymers, respectively. Studies were conducted on dissolution/permeation, apparent permeability (Papp), apparent solubility (Sapp), and absorption using synthetic and biological membranes. Based on these results, the amount of EB in the microparticles needed to achieve a therapeutic dose was estimated. The EB−ALG microparticles outperformed both EB−SOL and free EB, for all parameters analyzed. The results show values of 0.45 mg/mL (80.2%) for dissolution/permeation, a Papp of 6.2 mg/mL in RS−L, an absorption of 7.3% in RS, and a Sapp of 53.1% in EM medium. The EB−ALG microparticles decrease the therapeutic dose necessary to control the parasite, with values of 3.0−2 mg/mL and 1.1−2 mg/mL for EB in EM and RS, respectively. The Korsmeyer−Peppas kinetic model was the best model to fit the EB−ALG and EB−SOL dissolution/permeation experiments. In addition, some of our experimental results using synthetic membranes are similar to those obtained with biological membranes, which suggests that, for some parameters, it is possible to replace biological membranes with synthetic membranes. The encapsulation of EB by ionic gelation shows it is a promising formulation to increase the absorption of the poorly soluble drug. In contrast, the spray-dried microparticles produced using Soluplus® result in even less dissolution/permeation than free EB, so the technique cannot be used to improve the solubility of EB.

Using Chitosan-Coated Polymeric Nanoparticles-Thermosensitive Hydrogels in association with Limonene as Skin Drug Delivery Strategy

Topical delivery of local anesthetics (LAs) is commonly used to decrease painful sensations, block pain throughout procedures, and alleviate pain after surgery. Dermal and/or transdermal delivery of LAs has other advantages, such as sustained drug delivery and decreased systemic adverse effects. This study reports the development of poly(D,L-lactide-co-glycolide) (PLGA) nanoparticles coated with chitosan for the sustained release and topicality of benzocaine (BZC) and topical delivery. BZC PLGA nanoparticles or nonencapsulated drugs were further incorporated into Poloxamer hydrogels (Pluronic™ F-127). The nanoparticles showed a mean diameter of 380 ± 4 nm, positive zeta potential after coating with chitosan (23.3 ± 1.7 mV), and high encapsulation efficiency (96.7 ± 0.02%). Cellular viability greater than 70% for both fibroblasts and keratinocytes was observed after treatment with nanoparticles, which is in accordance with the preconized guidelines for biomedical devices and delivery systems. Both the nanoparticles and hydrogels were able to modulate BZC delivery and increase drug permeation when compared to the nonencapsulated drug. Furthermore, the incorporation of limonene into hydrogels containing BZC-loaded nanoparticles increased the BZC permeation rates. Non-Newtonian and pseudoplastic behaviors were observed for all hydrogel nanoformulations with or without nanoparticles. These results demonstrate that the hydrogel-nanoparticle hybrids could be a promising delivery system for prolonged local anesthetic therapy.

Design, Physicochemical Characterization, and In Vitro Permeation of Innovative Resatorvid Topical Formulations for Targeted Skin Drug Delivery

Nonmelanoma skin cancers (NMSCs) are the most common malignancies worldwide and affect more than 5 million people in the United States every year. NMSC is directly linked to the excessive exposure of the skin to solar ultraviolet (UV) rays. The toll-like receptor 4 (TLR4) antagonist, resatorvid (TAK-242), is a novel prototype chemo preventive agent that suppresses the production of inflammation mediators induced by UV exposure. This study aimed to design and develop TAK-242 into topical formulations using FDA-approved excipients, including DermaBase^TM, PENcream^TM, polyethylene glycol (PEG)-400, propylene glycol (PG), carbomer gel, hyaluronic acid (HA) gel, and Pluronic^® F-127 poloxamer triblock copolymer gel for the prevention of skin cancer. The physicochemical properties of raw TAK-242, which influence the compatibility and solubility in the selected base materials, were confirmed using X-ray powder diffraction (XRPD), differential scanning calorimetry (DSC), hot-stage microscopy (HSM), Raman spectroscopy, and attenuated total reflectance Fourier-transform infrared (ATR-FTIR) spectroscopic analysis. The permeation behavior of TAK-242 from the prepared formulations was determined using Strat-M^® transdermal diffusion membranes, and 3D cultured primary human-derived epidermal keratinocytes (EpiDerm^TM). Despite TAK-242′s high molecular weight and hydrophobicity, it can permeate through reconstructed human epidermis from all formulations. The findings, reported for the first time in this study, emphasize the capabilities of the topical application of TAK-242 via these multiple innovative topical drug delivery formulation platforms.

Comparison of Synthetic Membranes to Heat-Separated Human Epidermis in Skin Permeation Studies In Vitro

In recent years, the study of dermal preparations has received increased attention. There are more and more modern approaches to evaluate transdermal formulations, which are crucial in proving the efficacy of a formulation. The aim of this study was to compare permeation across innovative synthetic membranes (Strat-M and Skin PAMPA membranes) and heat-separated human epidermis (HSE, gold standard membrane) using four different dermal formulations. The Strat-M and Skin PAMPA membranes were designed to mimic the stratum corneum layer of the human epidermis. There have also been some publications on their use in dermal formulation development, but further information is needed. Drug permeation was measured using formulations containing diclofenac sodium (two hydrogels and two creams). The HSE, Strat-M, and Skin PAMPA membranes proved to be significantly different, but based on the results, the Strat-M membrane showed the greatest similarity to HSE. The permeation data of the different formulations across different membranes showed good correlations with formulations similar to these four, which allows the prediction of permeation across HSE using these synthetic membranes. In addition, Strat-M and Skin PAMPA membranes have the potential to select and differentiate a dermal formulation containing diclofenac sodium as an early screening model.

Assessment of the Effect of Structural Modification of Ibuprofen on the Penetration of Ibuprofen from Pentravan® (Semisolid) Formulation Using Human Skin and a Transdermal Diffusion Test Model

The effect of transdermal vehicle (Pentravan®) on skin permeability was examined for unmodified ibuprofen (IBU) and ion pairs of ibuprofen with new L-valine alkyl esters [ValOR][IBU]. The percutaneous permeation across the human skin and transdermal diffusion test model (Strat-M® membranes) of ibuprofen and its structural modification were measured and compared using Franz diffusion cells. For comparison, the penetration of ibuprofen from a commercial product was also investigated. The cumulative amount of drug permeated through human skin at the end of the 24 h study was highest for ibuprofen derivatives containing propyl (C3), isopropyl (C3), ethyl (C2), and butyl (C4) esters. For Strat-M®, the best results were obtained with the alkyl chain length of the ester from C2 to C5. The permeation profiles and parameters were appointed, such as steady-state flux, lag time, and permeability coefficient. It has been shown that L-valine alkyl ester ibuprofenates, with the propyl, butyl, and amyl chain, exhibit a higher permeation rate than ibuprofen. The diffusion parameters of analyzed drugs through human skin and Strat-M® were similar and with good correlation. The resulting Pentravan-based creams with ibuprofen in the form of an ionic pair represent a potential alternative to other forms of the drug-containing analgesics administered transdermally. Furthermore, the Strat-M® membranes can be used to assess the permeation of transdermal preparations containing anti-inflammatory drugs.

Dissolving microneedle patches loaded with amphotericin B microparticles for localised and sustained intradermal delivery: Potential for enhanced treatment of cutaneous fungal infections

Fungal infections affect millions of people globally and are often unreceptive to conventional topical or oral preparations because of low drug bioavailability at the infection site, lack of sustained therapeutic effect, and the development of drug resistance. Amphotericin B (AmB) is one of the most potent antifungal agents. It is increasingly important since fungal co-infections associated with COVID-19 are frequently reported. AmB is only administered via injections (IV) and restricted to life-threatening infections due to its nephrotoxicity and administration-related side effects. In this work, we introduce, for the first time, dissolving microneedle patches (DMP) loaded with micronised particles of AmB to achieve localised and long-acting intradermal delivery of AmB for treatment of cutaneous fungal infections. AmB was pulverised with poly (vinyl alcohol) and poly (vinyl pyrrolidone) to form micronised particles-loaded gels, which were then cast into DMP moulds to form the tips. The mean particle size of AmB in AmB DMP tips after pulverisation was 1.67 ± 0.01 μm. This is an easy way to fabricate and load microparticles into DMP, as few steps are required, and no organic solvents are needed. AmB had no covalent chemical interaction with the excipients, but the crystallinity of AmB was reduced in the tips. AmB was completely released from the tips within 4 days in vitro. AmB DMP presented inhibition of Candida albicans (CA) and the killing rate of AmB DMP against CA biofilm inside porcine skin reached 100% within 24 h. AmB DMP were able to pierce excised neonatal porcine skin at an insertion depth of 301.34 ± 46.86 μm. Ex vivo dermatokinetic and drug deposition studies showed that AmB was mainly deposited in the dermis. An in vivo dermatokinetic study revealed that the area under curve (AUC_0-inf) values of AmB DMP and IV (Fungizone® bolus injection 1 mg/kg) groups were 8823.0 d∙μg/g and 33.4 d∙μg/g, respectively (264-fold higher). AmB remained at high levels (219.07 ± 102.81 μg/g or more) in the skin until 7 days after the application of AmB DMP. Pharmacokinetic and biodistribution studies showed that AmB concentration in plasma, kidney, liver, and spleen in the AmB DMP group was significantly lower than that in the IV group. Accordingly, this system addressed the systemic side effects of intravenous injection of AmB and localised the drug inside the skin for a week. This work establishes a novel, easy and effective method for long-acting and localised intradermal drug delivery.

Permeability of Ibuprofen in the Form of Free Acid and Salts of L-Valine Alkyl Esters from a Hydrogel Formulation through Strat-M™ Membrane and Human Skin

This paper aimed to evaluate the effect of vehicle and chemical modifications of the structure of active compounds on the skin permeation and accumulation of ibuprofen [IBU]. In vitro permeation experiments were performed using human abdominal skin and Strat-M™ membrane. The HPLC method was used for quantitative determinations. The formulations tested were hydrogels containing IBU and its derivatives and commercial gel with ibuprofen. The results obtained indicate that Celugel® had an enhancing effect on the skin penetration of IBU. The average cumulative mass of [IBU] after 24 h permeation test from Celugel® formulation through human skin was over 3 times higher than for the commercial product. Three ibuprofen derivatives containing [ValOiPr][IBU], [ValOPr][IBU], and [ValOBu][IBU] cation were evaluated as chemical penetration enhancers. The cumulative mass after 24 h of penetration was 790.526 ± 41.426, 682.201 ± 29.910, and 684.538 ± 5.599 μg IBU cm-2, respectively, compared to the formulation containing unmodified IBU-429.672 ± 60.151 μg IBU cm-2. This study demonstrates the perspective of the transdermal hydrogel vehicle in conjunction with the modification of the drug as a potential faster drug delivery system.

Development of a Mosquito Repellent Formulation Based on Nanostructured Lipid Carriers

Arboviral diseases are a threat to global public health systems, with recent data suggesting that around 40% of the world's population is at risk of contracting arboviruses. The use of mosquito repellents is an appropriate strategy to avoid humans coming into contact with vectors transmitting these viruses. However, the cost associated with daily applications of repellents can make their use unfeasible for the low-income populations that most need protection. Therefore, the development of effective formulations offers a way to expand access to this means of individual protection. Consequently, research efforts have focused on formulations with smaller quantities of active agents and sustained release technology, aiming to reduce re-applications, toxicity, and cost. The present study investigates the development of nanostructured lipid carriers (NLCs) loaded with a mixture of the compounds icaridin (synthetic) and geraniol (natural), incorporated in cellulose hydrogel. The NLCs were prepared by the emulsion/solvent evaporation method and were submitted to physicochemical characterization as a function of time (at 0, 15, 30, and 60 days). The prepared system presented an average particle size of 252 ± 5 nm, with encapsulation efficiency of 99% for both of the active compounds. The stability profile revealed that the change of particle size was not significant (p > 0.05), indicating high stability of the system. Rheological characterization of the gels containing NLCs showed that all formulations presented pseudoplastic and thixotropic behavior, providing satisfactory spreadability and long shelf life. Morphological analysis using atomic force microscopy (AFM) revealed the presence of spherical nanoparticles (252 ± 5 nm) in the cellulose gel matrix. Permeation assays showed low fluxes of the active agents through a Strat-M^® membrane, with low permeability coefficients, indicating that the repellents would be retained on the surface to which they are applied, rather than permeating the tissue. These findings open perspectives for the use of hybrid formulations consisting of gels containing nanoparticles that incorporate repellents effective against arthropod-borne virus. These systems could potentially provide improvements considering the issues of effectiveness, toxicity, and safety.

Lipid Nanoparticulate Drug Delivery Systems: Recent Advances in the Treatment of Skin Disorders

The multifunctional role of the human skin is well known. It acts as a sensory and immune organ that protects the human body from harmful environmental impacts such as chemical, mechanical, and physical threats, reduces UV radiation effects, prevents moisture loss, and helps thermoregulation. In this regard, skin disorders related to skin integrity require adequate treatment. Lipid nanoparticles (LN) are recognized as promising drug delivery systems (DDS) in treating skin disorders. Solid lipid nanoparticles (SLN) together with nanostructured lipid carriers (NLC) exhibit excellent tolerability as these are produced from physiological and biodegradable lipids. Moreover, LN applied to the skin can improve stability, drug targeting, occlusion, penetration enhancement, and increased skin hydration compared with other drug nanocarriers. Furthermore, the features of LN can be enhanced by inclusion in suitable bases such as creams, ointments, gels (i.e., hydrogel, emulgel, bigel), lotions, etc. This review focuses on recent developments in lipid nanoparticle systems and their application to treating skin diseases. We point out and consider the reasons for their creation, pay attention to their advantages and disadvantages, list the main production techniques for obtaining them, and examine the place assigned to them in solving the problems caused by skin disorders.

Xenon as a transdermal enhancer for niacinamide in Strat-M™ membranes

Xenon is confirmed to diffuse readily through membranes and has properties of transdermal enhancer. In this study, the ability of xenon to regulate the transdermal diffusion of niacinamide was investigated using a model of an artificial skin analogue of Strat-M™ membranes in Franz cells. Based on the data obtained, we found that in the simplified biophysical model of Strat-M™ membranes xenon exerts its enhancer effect based on the heterogeneous nucleation of xenon at the interfaces in the microporous structures of Strat-M™ membranes.

Optimization and Evaluation of the In Vitro Permeation Parameters of Topical Products with Non-Steroidal Anti-Inflammatory Drugs through Strat-M® Membrane

Pharmaceutical products containing non-steroidal anti-inflammatory drugs (NSAIDs) are among the most prescribed topical formulations used for analgesic and antirheumatic properties. These drugs must overcome the skin barrier to cause a therapeutic effect. Human skin has been widely used as a model to study in vitro drug diffusion and permeation, however, it suffers from many limitations. Therefore, to perform in vitro permeation test (IVPT), we used a Strat-M^® membrane with diffusion characteristics well-correlated to human skin. This study’s objective was to optimize the IVPT conditions using Plackett–Burman experimental design for bio-predictive evaluation of the in vitro permeation rates of five non-steroidal anti-inflammatory drugs (diclofenac, etofenamate, ibuprofen, ketoprofen, naproxen) across Strat-M^® membrane from commercial topical formulations. The Plackett–Burman factorial design was used to screen the effect of seven factors in eight runs with one additional center point. This tool allowed us to set the sensitive and discriminative IVPT final conditions that can appropriately characterize the NSAIDs formulations. The permeation rate of etofenamate (ETF) across the Strat-M^® membrane was 1.7–14.8 times faster than other NSAIDs from selected semisolids but 1.6 times slower than the ETF spray formulation.

Potent antifungal agents and use of nanocarriers to improve delivery to the infected site: A systematic review

There are four major classes of antifungals with the predominant mechanism of action being targeting of cell wall or cell membrane. As in other drugs, low solubility of these compounds has led to low bioavailability in target tissues. Enhanced drug dosages have effects such as toxicity, drug-drug interactions, and increased drug resistance by fungi. This article reviews the current state-of-the-art of antifungals, structure, mechanism of action, other usages, and toxic side effects. The emergence of nanoformulations to transport and uniformly release cargo at the target site is a boon in antifungal treatment. The article details research that lead to the development of nanoformulations of antifungals and potential advantages and avoidance of the lacunae characterizing conventional drugs. A range of nanoformulations based on liposomes, polymers are in various stages of research and their potential advantages have been brought out. It could be observed that under similar dosages, test models, and duration, nanoformulations provided enhanced activity, reduced toxicity, higher uptake and higher immunostimulatory effects. In most instances, the mechanism of antifungal activity of nanoformulations was similar to that of regular antifungal. There are possibilities of coupling multiple antifungals on the same nano-platform. Increased activity coupled with multiple mechanisms of action presents for nanoformulations a tremendous opportunity to overcome antifungal resistance. In the years to come, robust methods for the preparation of nanoformulations taking into account the repeatability and reproducibility in action, furthering the studies on nanoformulation toxicity and studies of human models are required before extensive use of nanoformulations as a prescribed drug.

Cationic liposomes mediated transdermal delivery of meloxicam and ketoprofen: Optimization of the composition, in vitro and in vivo assessment of efficiency

New liposomes modified with pyrrolidinium surfactants containing a hydroxyethyl fragment (C_nPB, n = 12, 14, 16) were prepared for transdermal delivery of non-steroidal anti-inflammatory drugs. In order to obtain the optimal composition, the surfactant/lipid molar ratio (0.02/1; 0.029/1; 0.04/1) and the amphiphile hydrocarbon tail length were varied. Rhodamine B was loaded in all formulations, while meloxicam and ketoprofen in selected ones. For liposomes studied the hydrodynamic diameter was in the range of 80-130 nm, the zeta potential ranged from +35 to +50 mV, EE was 75-99%. Liposome modification leads to a prolonged release of the rhodamine B (up to 10-12 h) and faster release of non-steroidal drugs (up to 7-8 h) in vitro. The ability to cross the skin barrier using Franz cells was investigated for liposomal meloxicam and ketoprofen. The total amount of meloxicam and ketoprofen passed through the Strat-M® membranes during 51 h was 51-114 μg/cm² and 87-105 μg/cm² respectively. The evaluation of transdermal diffusion ex vivo showed that total amount of liposomal ketoprofen passed through the skin during 51 h was 140-162 μg/cm². Liposomes modified with C₁₆PB were found as the most effective inflammation reducing formulation in the carrageenan edema model of rat paw.

Lanolin-Based Synthetic Membranes for Transdermal Permeation and Penetration Drug Delivery Assays

Due to the high similarity in composition and structure between lanolin and human SC lipids, we will work with two models from wool wax. Two types of lanolin were evaluated: one extracted with water and surfactants (WEL) and the other extracted with organic solvents (SEL). Skin permeation and skin penetration studies were performed with two active compounds to study the feasibility of the use of lanolin-based synthetic membranes as models of mammalian skin. Diclofenac sodium and lidocaine were selected as the active compounds considering that they have different chemical natures and different lipophilicities. In the permeation assay with SEL, a better correlation was obtained with the less permeable compound diclofenac sodium. This assay suggests the feasibility of using artificial membranes with SEL as a model for percutaneous absorption studies, even though the lipophilic barrier should be improved. Penetration profiles of the APIs through the SEL and WEL membranes indicated that the two membranes diminish penetration and can be considered good membrane surrogates for skin permeability studies. However, the WEL membranes, with a pH value similar to that of the skin surface, promoted a higher degree of diminution of the permeability of the two drugs, similar to those found for the skin.

Comparison Study of the Effects of Cationic Liposomes on Delivery across 3D Skin Tissue and Whitening Effects in Pigmented 3D Skin

Charged phospholipids are employed to formulate liposomes with different surface charges to enhance the permeation of active ingredients through epidermal layers. Although 3D skin tissue is widely employed as an alternative to permeation studies using animal skin, only a small number of studies have compared the difference between these skin models. Liposomal delivery strategies are investigated herein, through 3D skin tissue based on their surface charges. Cationic, anionic, and neutral liposomes are formulated and their size, zeta-potential, and morphology are characterized using dynamic light scattering and cryogenic-transmission electron microscopy (cryo-TEM). A Franz diffusion cell is employed to determine the delivery efficiency of various liposomes, where all liposomes do not exhibit any recognizable difference of permeation through the synthetic membrane. When the fluorescence liposomes are applied to 3D skin, considerable fluorescence intensity is observed at the stratum cornea and epithelium layers. Compared to other liposomes, cationic liposomes exhibit the highest fluorescence intensity, suggesting the enhanced permeation of liposomes through the 3D skin layers. Finally, the ability of niacinamide (NA)-incorporated liposomes to suppress melanin transfer in pigmented 3D skin is examined, where cationic liposomes exhibit the highest degree of whitening effects.

Fabrication of hollow microneedles using liquid crystal display (LCD) vat polymerization 3D printing technology for transdermal macromolecular delivery

The present study aimed to fabricate a hollow microneedle device consisting of an array and a reservoir by means of 3D printing technology for transdermal peptide delivery. Hollow microneedles (HMNs) were fabricated using a biocompatible resin material, while PLA filament was used for the reservoirs. The fabricated microdevice was characterized by means of optical microscopy, scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), contact angle measurements and leakage inspection studies to ensure the passageway of liquid formulations. Mechanical failure and penetration tests were carried out and supported by Finite Element Analysis (FEA). The cytocompatibility of the microneedle arrays was assessed to human keratinocytes (HaCaT). Finally, the transport of the model peptide octreotide acetate across artificial membranes was assessed in Franz cells using the aforementioned HMN design.

Phenethyl Isothiocyanate-Containing Carbomer Gel for Use against Squamous Cell Carcinoma

It is currently estimated that one in every five Americans will develop skin cancer during their lifetime. Squamous cell carcinoma (SCC) is a common type of skin cancer that can develop due to the skin’s exposure to the sun. Herein, we prepared a topical gel containing 0.5% v/w phenethyl isothiocyanate (PEITC) for the treatment of SCC. PEITC is a naturally occurring isothiocyanate that has been shown to have efficacy against various types of cancer in preclinical studies. We first incorporated PEITC into a carbomer gel. A uniform formulation was prepared, and its viscosity was appropriate for topical application. We then demonstrated the release of PEITC from the gel into and through a Strat-M skin-like membrane. Finally, the effects of the PEITC-containing gel were tested against SCC and normal keratinocytes skin cells in culture, and these results were compared to those obtained for free 5-fluoruracil (5-FU), a commonly used skin-cancer drug. Our results show that a homogeneous PEITC-containing topical gel can be prepared and used to kill SCC cells. Thus, our formulation may be useful for treating SCC in the clinic.

Comparison of the In Vitro and Ex Vivo Permeation of Existing Topical Formulations Used in the Treatment of Facial Angiofibroma and Characterization of the Variations Observed

Rapamycin has been used topically to treat facial angiofibromas associated with tuberous sclerosis for more than a decade. In the absence of a commercial form, a large number of formulations have been clinically tested. However, given the great heterogeneity of these studies, particularly with regard to the response criteria, it was difficult to know the impact and thus to compare the relevance of the formulations used. The objective of this work was therefore to evaluate the link between the diffusion of rapamycin and the physico-chemical characteristics of these different formulations on Strat-M^® membranes as well as on human skin using Franz cells. Our results underline the importance of the type of vehicle used (hydrogel > cream > lipophilic ointment), the soluble state of rapamycin and its concentration close to saturation to ensure maximum thermodynamic activity. Thus, this is the first time that a comparative study of the different rapamycin formulations identified in the literature for the management of facial angiofibromas has been carried out using a pharmaceutical and biopharmaceutical approach. It highlights the important parameters to be considered in the development and optimization of topical rapamycin formulations with regard to cutaneous absorption for clinical efficacy.

Ultradeformable Lipid Vesicles Localize Amphotericin B in the Dermis for the Treatment of Infectious Skin Diseases

Cutaneous fungal and parasitic diseases remain challenging to treat, as available therapies are unable to permeate the skin barrier. Thus, treatment options rely on systemic therapy, which fail to produce high local drug concentrations but can lead to significant systemic toxicity. Amphotericin B (AmB) is highly efficacious in the treatment of both fungal and parasitic diseases such as cutaneous leishmaniasis but is reserved for parenteral administration in patients with severe pathophysiology. Here, we have designed and optimized AmB-transfersomes [93.5% encapsulation efficiency, 150 nm size, and good colloidal stability (-35.02 mV)] that can remain physicochemically stable (>90% drug content) at room temperature and 4 °C over 6 months when lyophilized and stored under desiccated conditions. AmB-transfersomes possessed good permeability across mouse skin (4.91 ± 0.41 μg/cm²/h) and 10-fold higher permeability across synthetic Strat-M membranes. In vivo studies after a single topical application in mice showed permeability and accumulation within the dermis (>25 μg AmB/g skin 6 h postadministration), indicating the delivery of therapeutic amounts of AmB for mycoses and cutaneous leishmaniasis, while a single daily administration in Leishmania (Leishmania) amazonensis infected mice over 10 days, resulted in excellent efficacy (98% reduction in Leishmania parasites). Combining the application of AmB-transfersomes with metallic microneedles in vivo increased the levels in the SC and dermis but was unlikely to elicit transdermal levels. In conclusion, AmB-transfersomes are promising and stable topical nanomedicines that can be readily translated for parasitic and fungal infectious diseases.

Nanofibrous cosmetic face mask for transdermal delivery of nano gold: synthesis, characterization, release and zebra fish employed toxicity studies

This study involves the generation of gold nanoparticles (Au NPs) via a novel natural/non-toxic methodology using tea and orange-peel extracts. These were then embedded into a novel blend composed of a polyethylene oxide and gelatin (PEO-Gel) fibre mat. The scanning electron microscopy results indicated that the addition of both collagen (COL) and ascorbic acid (AA) into the PEO-Gel system (PEO-Gel-AA-COL system) enhances the Au NP incorporation into nanofibres leading to a diameter of 164.60 ± 20.95 and 192.43 ± 39.14 nm in contrast to the spraying observed with the Au PEO-Gel system alone. Releasing studies conducted over 30 min indicated that the PEO-Gel-AA-COL-orange peel Au (OpAu) system accounts for a higher content of Au release than the green tea Au (GtAu) NP system where a maximum release could be attained within 10-30 min depending on the amount of Au NPs that have been incorporated. Moreover, the transdermal diffusion studies conducted using Strat membrane indicated that Au NPs from both formulations (PEO-Gel-AA-COL-GtAu nanofibre, PEO-Gel-AA-COL-OpAu nanofibre) have diffused through the stratum corneum and trapped in the dermis and epidermis indicating its transdermal deliverability. Additionally, 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay revealed that nanofibres have similar radical scavenging activity like AA standard. Toxicity evaluation on a zebra fish embryo model confirmed that both GtAu NPs and OpAu NPs do not induce any teratogenic activity and are safe to be used in the range of 1.0-167 µg ml-1.

Evolution of Nanotechnology in Delivering Drugs to Eyes, Skin and Wounds via Topical Route

The topical route is the most preferred one for administering drugs to eyes, skin and wounds for reaching enhanced efficacy and to improve patient compliance. Topical administration of drugs via conventional dosage forms such as solutions, creams and so forth to the eyes is associated with very low bioavailability (less than 5%) and hence, we cannot rely on these for delivering drugs to eyes more efficiently. An intravitreal injection is another popular drug delivery regime but is associated with complications like intravitreal hemorrhage, retinal detachment, endophthalmitis, and cataracts. The skin has a complex structure that serves as numerous physiological barriers to the entry of exogenous substances. Drug localization is an important aspect of some dermal diseases and requires directed delivery of the active substance to the diseased cells, which is challenging with current approaches. Existing therapies used for wound healing are costly, and they involve long-lasting treatments with 70% chance of recurrence of ulcers. Nanotechnology is a novel and highly potential technology for designing formulations that would improve the efficiency of delivering drugs via the topical route. This review involves a discussion about how nanotechnology-driven drug delivery systems have evolved, and their potential in overcoming the natural barriers for delivering drugs to eyes, skin and wounds.

3D-printed microfluidic chip for the preparation of glycyrrhetinic acid-loaded ethanolic liposomes

18-α-Glycyrrhetinic acid (GA) is a bioactive compound extracted from licorice that exhibits many biological and pharmacological effects such as anti-inflammatory and antioxidant activities on the skin. However, its lipophilic nature results in poor bioavailability that limits clinical applications. Liposomes, presenting the ability to carry both hydrophobic and hydrophilic payloads and a good cytocompatibility, are effective to overcome this barrier. Furthermore, the addition of permeation enhancers such as ethanol into liposomal formulations helps the diffusion of these systems through the skin barrier. Here, we aimed to formulate GA-loaded ethanolic liposomes, using a natural soybean lecithin via a microfluidic approach. Using a fused deposition modeling (FDM) 3D printer we customized a microfluidic chip, and manufactured vesicles that presented spherical shape with a size of 202 ± 5.2 nm, a narrow size distribution and a good stability over a period of 30 days. After reaching a drug encapsulation efficiency of 63.15 ± 2.2%, liposomes were evaluated for their cytocompatibility and skin permeation potentiality after hydrogelation using xanthan gum. The in vitro release and permeation studies were performed using Franz diffusion cells comparing two different media and three synthetic membranes including a polymeric skin-mimicking membrane. The selected formulation presented no cytotoxicity and an increased permeation compared to GA saturated hydrogel. It could perform therapeutically better effects than conventional formulations containing free GA, as prolonged and controlled release topical dosage forms, which may lead to improved efficiency and better patient compliance.

Rabbit Ear Membranes as an Interesting Alternative for Permeability Tests in the Preformulation Stages of Cosmetic Products

In the pre-formulation stages of cosmetic products, in vitro permeability tests correspond to an important alternative for making better decisions regarding the stability, performance and biocompatibility of these products. Moreover, these tests allow us to establish whether a cosmetic ingredient can penetrate the different layers of the skin, which is essential in these products. This study was focused on the extraction, characterization and preservation of rabbit ear membranes and their subsequent performance comparison against two synthetic membranes (cellulose and Strat-MTM). For this, the rabbit ear stratum corneum was isolated and characterized histologically, using the Hematoxylin and Eosin (HE) staining protocol along with light microscopy and image analysis. Then, the Frank diffusion cell (FC) model was employed to evaluate and compare the permeability of the model compound Naproxen sodium (NPX) between the three membrane systems. The results show that NPX permeability is strongly affected by the type of membrane, and the implementation of rabbit ear membranes shows high reproducibility, demonstrating that this model could be implemented during pre-formulation studies of cosmetic products.

Permeation kinetics of active drugs through lanolin-based artificial membranes

Skin-penetration studies play an essential role in the selection of drugs for dermal or transdermal application. In vivo experiments in humans are not always possible for ethical, practical, or economic reasons, especially in the first part of the drug development. It is necessary to develop alternative methods using accessible and reproducible surrogates for in vivo human skin. The in vitro methodologies using biological membranes (human and animal skin) are recognized and well accepted as an alternative but present high inter- and intra-individual variability. Therefore, the formation of synthetic membranes has been studied to obtain skin- mimicking models for permeation studies. The aim of this work is to create lanolin-based artificial membranes that can mimic the absorption through the skin of compounds applied topically. A series of synthetic membranes using two different types of lanolin (water-extracted (WE) and solvent-extracted (SE)) were prepared. Next, the in vitro release test of three drugs (diclofenac sodium, ibuprofen and lidocaine) was performed on artificial membranes and on porcine skin placed on Franz cells. The percentage of release, flux, permeability coefficient, lag time, area under the curve, maximal concentration and time were determined for each compound in the different types of membrane. The results showed that lanolin membranes presented a strong diminution of permeability compared to most artificial membranes, leading to a very similar permeability to that of skin. The SE and WE membranes showed a diminution of transepidermal water loss and permeability of compounds compared with membranes alone. The results from WE membranes were similar to those found for the skin. The lanolin membranes were not capable of perfectly mimicking permeation through the skin, but they did have the same rank order of drug penetration as the skin. It may be deduced from these tests that these systems provide more reliable results for compounds with low to medium lipophilicity. The results demonstrated that new lanolin-based artificial membranes have the potential to be exploited as screening models for determining the permeability of a compound destined to be topically delivered.

Personalised 3D Printed Medicines: Optimising Material Properties for Successful Passive Diffusion Loading of Filaments for Fused Deposition Modelling of Solid Dosage Forms

Although not readily accessible yet to many community and hospital pharmacists, fuse deposition modelling (FDM) is a 3D printing technique that can be used to create a 3D pharmaceutical dosage form by employing drug loaded filaments extruded via a nozzle, melted and deposited layer by layer. FDM requires printable filaments, which are commonly manufactured by hot melt extrusion, and identifying a suitable extrudable drug-excipient mixture can sometimes be challenging. We propose here the use of passive diffusion as an accessible loading method for filaments that can be printed using FDM technology to allow for the fabrication of oral personalised medicines in clinical settings. Utilising Hansen Solubility Parameters (HSP) and the concept of HSP distances (Ra) between drug, solvent, and filament, we have developed a facile pre-screening tool for the selection of the optimal combination that can provide a high drug loading (a high solvent-drug Ra, >10, and an intermediate solvent-filament Ra value, ~10). We have identified that other parameters such as surface roughness and stiffness also play a key role in enhancing passive diffusion of the drug into the filaments. A predictive model for drug loading was developed based on Support Vector Machine (SVM) regression and indicated a strong correlation between both Ra and filament stiffness and the diffusion capacity of a model BCS Class II drug, nifedipine (NFD), into the filaments. A drug loading, close to 3% w/w, was achieved. 3D printed tablets prepared using a PVA-derived filament (Hydrosupport, 3D Fuel) showed promising characteristics in terms of dissolution (with a sustained release over 24 h) and predicted chemical stability (>3 years at 25 °C/60% relative humidity), similar to commercially available NFD oral dosage forms. We believe FDM coupled with passive diffusion could be implemented easily in clinical settings for the manufacture of tailored personalised medicines, which can be stored over long periods of time (similar to industrially manufactured solid dosage forms).

Evaluation of Formulation Parameters on Permeation of Ibuprofen from Topical Formulations Using Strat-M® Membrane

Topical drug delivery is an attractive alternative to conventional methods because of advantages such as non-invasive delivery, by-pass of first pass metabolism, and improved patient compliance. However, several factors such as skin, physicochemical properties of the drug, and vehicle characteristics influence the permeation. Within a formulation, critical factors such as concentration of drug, physical state of drug in the formulation, and organoleptic properties affect the flux across the skin. The aim of the study was to develop and investigate topical semisolid preparations (creams and gels) with ibuprofen as the model drug and investigate the effect of various formulation parameters on the in-vitro performance across the Strat-M® membrane using flow-through cells. In addition, the physical stability of the developed formulations was investigated by studying viscosity, pH, and appearance. All the formulations developed in the study had appealing appearance with smooth texture and no signs of separation. Viscosity and pH of the formulations were acceptable. Cumulative amount of drug permeated at the end of 24 h was highest for clear gel (3% w/w ibuprofen; F6: 739.6 ± 36.1 µg/cm2) followed by cream with high concentration of ibuprofen in suspended form (5% w/w; F3: 320.8 ± 17.53 µg/cm2), emulgel (3% w/w ibuprofen; F5: 178.5 ± 34.5 µg/cm2), and cream with solubilized ibuprofen (3% w/w; F2A: 163.2 ± 9.36 µg/cm2). Results from this study showed that permeation of ibuprofen was significantly influenced by formulation parameters such as concentration of ibuprofen (3% vs. 5% w/w), physical state of ibuprofen (solubilized vs. suspended), formulation type (cream vs. gel), mucoadhesive agents, and viscosity (high vs. low). Thus, findings from this study indicate that pharmaceutical formulation scientists should explore these critical factors during the early development of any new topical drug product in order to meet pre-determined quality target product profile.

Alternatives to Biological Skin in Permeation Studies: Current Trends and Possibilities

: The transdermal route of drugs has received increased attention in recent years due to numerous advantages over the oral and injectable routes, such as avoidance of the hepatic metabolism, protection of drugs from the gastrointestinal tract, sustained drug delivery, and good patient compliance. The assessment of ex vivo permeation during the pharmaceutical development process helps in understanding the product quality and performance of a transdermal delivery system. Generally, excised human skin relevant to the application site or animal skin is recommended for ex vivo permeation studies. However, the limited availability of the human skin and ethical issues surrounding the use of animal skin rendered these models less attractive in the permeation study. In the last three decades, enormous efforts have been put into developing artificial membranes and 3D cultured human skin models as surrogates to the human skin. This manuscript provides an insight on the European Medicines Agency (EMA) guidelines for permeation studies and the parameters affected when using Franz diffusion cells in the permeation study. The need and possibilities for skin alternatives, such as artificially cultured human skin models, parallel artificial membrane permeability assays (PAMPA), and artificial membranes for penetration and permeation studies, are comprehensively discussed.