Nanocarriers to Enhance the Accumulation of Vitamin K1 into the Skin

Nanocarriers for Drug Delivery: An Overview with Emphasis on Vitamin D and K Transportation

Mounting evidence shows that supplementation with vitamin D and K or their analogs induces beneficial effects in various diseases, e.g., osteoarticular, cardiovascular, or carcinogenesis. The use of drugs delivery systems via organic and inorganic nanocarriers increases the bioavailability of vitamins and analogs, enhancing their cellular delivery and effects. The nanotechnology-based dietary supplements and drugs produced by the food and pharmaceutical industries overcome the issues associated with vitamin administration, such as stability, absorption or low bioavailability. Consequently, there is a continuous interest in optimizing the carriers' systems in order to make them more efficient and specific for the targeted tissue. In this pioneer review, we try to circumscribe the most relevant aspects related to nanocarriers for drug delivery, compare different types of nanoparticles for vitamin D and K transportation, and critically address their benefits and disadvantages.

Design and development of topical liposomal formulations in a regulatory perspective

The skin is the absorption site for drug substances intended to treat loco-regional diseases, although its barrier properties limit the permeation of drug molecules. The growing knowledge of the skin structure and its physiology have supported the design of innovative nanosystems (e.g. liposomal systems) to improve the absorption of poorly skin-permeable drugs. However, despite the dozens of clinical trials started, few topically applied liposomal systems have been authorized both in the EU and the USA. Indeed, the intrinsic complexity of the topically applied liposomal systems, the higher production costs, the lack of standardized methods and the more stringent guidelines for assessing their benefit/risk balance can be seen as causes of such inefficient translation. The present work aimed to provide an overview of the physicochemical and biopharmaceutical characterization methods that can be applied to topical liposomal systems intended to be marketed as medicinal products, and the current regulatory provisions. The discussion highlights how such methodologies can be relevant for defining the critical quality attributes of the final product, and they can be usefully applied based on the phase of the life cycle of a liposomal product: to guide the formulation studies in the early stages of development, to rationally design preclinical and clinical trials, to support the pharmaceutical quality control system and to sustain post-marketing variations. The provided information can help define harmonized quality standards able to overcome the case-by-case approach currently applied by regulatory agencies in assessing the benefit/risk of the topically applied liposomal systems.

Transfersomes as alternative topical nanodosage forms for the treatment of skin disorders

Topical drug delivery is a promising approach to treat different skin disorders. However, it remains a challenge mainly due to the nature and rigidity of the nanosystems, which limit deep skin penetration, and the unsuccessful demonstration of clinical benefits; greater penetration by itself, does not ensure pharmacological success. In this context, transfersomes have appeared as promising nanosystems; deformability, their unique characteristic, allows them to pass through the epidermal microenvironment, improving the skin drug delivery. This review focuses on the comparison of transfersomes with other nanosystems (e.g., liposomes), discusses recent therapeutic applications for the topical treatment of different skin disorders and highlights the need for further studies to demonstrate significant clinical benefits of transfersomes compared with conventional therapies.

Development of curcumin-loaded composite phospholipid ethosomes for enhanced skin permeability and vesicle stability

Ethosomes are widely applied as the carriers for the transdermal delivery of hydrophobic and hydrophilic drugs. Herein, curcumin-loaded ethosomes (CE) with different phospholipid composition were formulated and thoroughly compared. A significant interaction between the unsaturated phosphatidylcholine (PC) and saturated hydrogenated phosphatidylcholine (HPC) was found by molecular simulation and differential scanning calorimetry (DSC), which led to the reduction of PC peroxidation with the presence of HPC. Subsequently, the composite phospholipid ethosomes containing curcumin were prepared for the first time to evaluate their properties in comparison with the conventional ethosomes composed of PC (CE-P) or HPC (CE-H). CE with PC/HPC ratio of 1:1 (CE-P1H1) with the best vesicle stability and flexibility significantly decreased the uptake by HaCaT cells compared to CE-H and free curcumin, indicating reduced skin cell toxicity. Compared with free curcumin, CE-P1H1 had the highest transdermal efficiency (p < 0.001), followed by CE-P (p < 0.05), partly due to the fact that CE-P1H1 could disturb lipid domain of stratum corneum (SC). Moreover, CE-P1H1 was found to promote curcumin for deep penetration of the skin via the hair follicles route. Our study has shown that using composite phospholipid ethosomes as lipid vesicular carriers could enhance transdermal penetration of drugs and increase in the vesicle stability.

Skin permeation and thermodynamic features of curcumin-loaded liposomes

This work describes the development of liposomes encapsulating curcumin (CURC) aiming to provide insights on the influence of CURC on the thermodynamic and skin permeation/penetration features of the vesicles. CURC-loaded liposomes were prepared by hydration of lipid film, in the 0.1-15% CURC:DPPC w/w ratio range. The obtained formulations were characterized for their size distribution, zeta potential and vesicle deformability, along with their thermodynamic properties and ex vivo skin penetration/permeation ability. Liposome size was 110-130 nm for all formulations, with fairly narrow size distribution (polydispersity index was ≤0.20) and a zeta potential mildly decreasing with CURC loading. DSC outcomes indicated that CURC interferes with the packing of DPPC acyl chains in liposome bilayer when CURC percentage was at least 10%, leading to a more fluid state than blank and low-payload vesicles. Consistently, the deformability index of liposomes with 15% CURC:DPPC was strongly increased compared to other formulations. This is congruent with ex vivo skin penetration/permeation results, which showed how more deformable liposomes showed an improved deposition in the epidermis, which acts as a reservoir for the active molecule. Altogether, results hint at a possible application of high payload liposomes for improved topical dermal accumulations of actives.

Polypeptide-corticosteroid conjugates as a topical treatment approach to psoriasis

Topical treatment of mild-to-moderate psoriasis with corticosteroids suffers from challenges that include reduced drug bioavailability at the desired site of action. The retention of therapeutics within the epidermis can safely treat skin inflammation, scaling, and erythema associated with psoriasis while avoiding possible side effects associated with systemic treatments. We successfully synthesized and characterized a pH-responsive biodegradable poly-L-glutamic acid (PGA)-fluocinolone acetonide (FLUO) conjugate that allows the controlled release of the FLUO to reduce skin inflammation. Additionally, the application of a hyaluronic acid (HA)-poly-L-glutamate cross polymer (HA-CP) vehicle boosted skin permeation. During in vitro and ex vivo analyses, we discovered that PGA-FLUO inhibited pro-inflammatory cytokine release, suggesting that polypeptidic conjugation fails to affect the anti-inflammatory activity of FLUO. Additionally, ex vivo human skin permeation studies using confocal microscopy revealed the presence of PGA-FLUO within the epidermis, but a minimal presence in the dermis, thereby reducing the likelihood of FLUO entering the systemic circulation. Finally, we demonstrated that PGA-FLUO applied within HA-CP effectively reduced psoriasis-associated phenotypes in an in vivo mouse model of human psoriasis while also lowering levels of pro-inflammatory cytokines in tissue and serum. Overall, our experimental results demonstrate that PGA-FLUO within an HA-CP penetration enhancer represents an effective topical treatment for psoriasis.

Vesicular nanocarrier based treatment of skin fungal infections: Potential and emerging trends in nanoscale pharmacotherapy

Occurrence of skin fungal infections is increasing nowadays and their presence is more prominent in patients suffering from immunocompromised diseases like AIDS. Skin fungal infections are a major cause of visits by patients to dermatology clinics. Although, a large number of antifungal agents are available for treatment of skin fungal infections, but, their toxic profile and physicochemical characteristics reduce therapeutic outcome. When these antifungal agents are delivered topically using conventional formulations like creams and gels, they may cause various side effects like redness, burning, and swelling at the site of application. Therefore, various vesicular formulations (phospholipid based or non phospholipid based) have been explored by pharmaceutical scientists to treat skin fungal infections topically. Vesicular formulation explored for the purpose are liposomes, ethosomes, transfersomes, transethosomes, niosomes, spanlastics, oleic acid vesicles, and nanoparticles. These formulations show various advantages like bioavailability enhancement of bioactives, high skin permeation power, no side effects at application site, dosing frequency reduction, and sustained drug release. Therefore, in the present article, we have discussed about the utility of various vesicular nanocarrier systems to treat skin fungal infections.

Tuning the Extent and Depth of Penetration of Flexible Liposomes in Human Skin

In this work we made an attempt to assess the effect of drug-induced changes of flexibility on the penetration of deformable vesicles into the human skin. Eight cationic liposomes with different degrees of flexibility were obtained by entrapping unfractionated heparin, enoxaparin, and nadroparin. The deformability was studied by a novel, facile, and reliable extrusion assay appositely developed and validated by means of quantitative nanoscale mechanical AFM measurements of vesicle elastic modulus (log₁₀(YM)). The proposed extrusion assay, determining the forces involved in vesicles deformation, resulted very sensitive to evidence of minimal changes in bilayer rigidity (σ) and vesicle deformation (K). The drug loading caused a reduction of liposome flexibility with respect to the reference plain liposomes and in accordance to the heparin type, drug to cationic lipid (DOTAP) ratio, and drug distribution within the vesicles. Interestingly, the σ and log₁₀(YM) values perfectly correlated (R² = 0.935), demonstrating the reliability of the deformability data obtained with both approaches. The combination of TEM and LC-MS/MS spectrometry allowed the pattern of the penetration of the entire vesicles into the skin to be followed. In all cases, intact liposomes in the epidermis layers were observed and a relationship between the depth of penetration and the liposome flexibility was found, supporting the hypothesis of the whole vesicle penetration mechanism. Moreover, the results of the extent (R₂₄) of vesicle penetration in the human skin samples showed a direct relation to the flexibility values (σ₁ = 0.65 ± 0.10 MPa → R₂₄ = 3.33 ± 0.02 μg/mg; σ₂ = 0.95 ± 0.04 MPa → R₂₄ = 1.18 ± 0.26 μg/mg; σ₃ = 1.89 ± 0.30 MPa → R₂₄ = 0.53 ± 0.33 μg/mg).

Nanoparticles as safe and effective delivery systems of antifungal agents: Achievements and challenges

Invasive fungal infections are becoming a major health concern in several groups of patients leading to severe morbidity and mortality. Moreover, cutaneous fungal infections are a major cause of visits to outpatient dermatology clinics. Despite the availability of several effective agents in the antifungal drug arena, their therapeutic outcome is less than optimal due to limitations related to drug physicochemical properties and toxicity. For instance, poor aqueous solubility limits the formulation options and efficacy of several azole antifungal drugs while toxicity limits the benefits of many other drugs. Nanoparticles hold great promise to overcome these limitations due to their ability to enhance drug aqueous solubility, bioavailability and antifungal efficacy. Further, drug incorporation into nanoparticles could greatly reduce its toxicity. Despite these interesting nanoparticle features, there are only few marketed nanoparticle-based antifungal drug formulations. This review sheds light on different classes of nanoparticles used in antifungal drug delivery, such as lipid-based vesicles, polymeric micelles, solid lipid nanoparticles, nanostructured lipid carriers, nanoemulsions and dendrimers with emphasis on their advantages and limitations. Translation of these nanoformulations from the lab to the clinic could be facilitated by focusing the research on overcoming problems related to nanoparticle stability, drug loading and high cost of production and standardization.

Development of nanoemulsions for topical delivery of vitamin K1

Vitamin K1 (VK1) is a natural and lipophilic compound currently used in dermatological formulations. In this work, nanoemulsions containing VK1 have been proposed to overcome some issues associated to semisolid VK1-incorporating formulations. The study has been focused on the design of a lipid-free aqueous formulation, easy to prepare and with low cost of production. Thus, a simply protocol, using a low-energy method, has been used to spontaneously form the nanoemulsions. The nanoemulsion composition has been optimized to improve its physical stability during storage in different conditions. Then, the possibility to administer VK1-containing nanoemulsions by nebulization without significant alteration of the formulation was tested. Moreover, the VK1 accumulation into the skin layers have been evaluated through permeation experiments on Franz cells, ATR-FITR analysis, confocal laser scanning microscopy (CLSM) observations, and high performance liquid chromatography (HPLC) analysis. The study demonstrated that NEs represent an interesting option for the commercial development of an aqueous spray formulation for the topical delivery of VK1.