Drug delivery systems based in microneedles for dermatological diseases and aesthetic enhancement.

Microneedle (MN) devices comprise of micron-sized structures that circumvent biological barriers in a minimally invasive manner. MN research continues to grow and evolve; the technology was recently identified as one of the top ten overall emerging technologies of 2020. There is a growing interest in using such devices in cosmetology and dermatological conditions where the MNs mechanically disrupt the outer skin barrier layer, creating transient pathways that allow the passage of materials to underlying skin layers. This review aims to appraise the application of microneedle technologies in skin science, provide information on potential clinical benefits, as well as indicate possible dermatological conditions that can benefit from this technology, including autoimmune-mediated inflammatory skin diseases, skin aging, hyperpigmentation, and skin tumors. A literature review was carried out to select studies that evaluated the use of microneedles as drug delivery enhancement for dermatologic purposes. MN patches create temporary pathways that allow the passage of material to deeper layers of the skin. Given their demonstrable promise in therapeutic applications, it will be essential for healthcare professionals to engage with these new delivery systems.

Elastic cationic liposomes for vitamin C delivery: Development, characterization and skin absorption study.

The influence of hydrophilic surfactants acting on the membrane elasticity of liposomes on the skin absorption of vitamin C is investigated. The purpose of encapsulation inside cationic liposomes is to improve the skin delivery of vitamin C. The properties of elastic liposomes (ELs) are compared to that of conventional liposomes (CLs). ELs are formed by the addition of the "edge activator" Polysorbate 80 to the CLs composed of soybean lecithin, cationic lipid DOTAP (1,2-dioleoyl-3-trimethylammoniopropane chloride), and cholesterol. The liposomes are characterized by dynamic light scattering and electron microscopy. No toxicity is detected in human keratinocyte cells. Evidences of Polysorbate 80 incorporation into liposome bilayers and of the higher flexibility of ELs are given by isothermal titration calorimetry and pore edge tension measurements in giant unilamellar vesicles. The presence of a positive charge in the liposomal membrane increases the encapsulation efficacy by approximately 30% for both CLs and ELs. Skin absorption of vitamin C from CLs, ELs and a control aqueous solution measured in Franz cells shows a high delivery of vitamin C into each skin layer and the acceptor fluid from both liposome types. These results suggest that another mechanism drives skin diffusion, involving interactions between cationic lipids and vitamin C depending on the skin pH.

Stabilization of vitamin C in emulsions of liquid crystalline structures.

Emulsified systems are widely used for topical delivery with the aim of optimizing cutaneous absorption and offering a pleasant sensory. They also may provide a protection of the active molecule against oxidation and/or degradation. The oil phase of o/w emulsions may consist of liquid crystalline structures, especially lamellar structures which are similar to those found in the stratum corneum lipids. In the present work, o/w emulsions containing liquid crystals of mixed cetyl alcohol and Polysorbate 60 were developed for topical delivery of vitamin C, a potent antioxidant with several applications in the cosmetic and pharmaceutical fields. In addition to the well-documented lipid supplementation of the stratum corneum, the liquid crystal emulsions provide a significant chemical stabilization of vitamin C against its degradation. Emulsions were characterized by X-ray diffraction, polarized optical microscopy, and transmission electron microscopy. The stability of vitamin C in the formulations was evaluated upon storage in different conditions of temperature. The emulsions contain a complex colloidal structure, consisting of lamellar liquid crystalline (Lα) and crystalline lamellar gel (Lß) phases, that provide a very efficient protection of vitamin C against its degradation.

Development and cathodic iontophoretic permeation evaluation of liquid crystalline systems provided of retinoic acid microparticles.

BACKGROUND: The intracellular form of action of retinoids requires these agents to reach deeper layers of the skin with viable cells to ensure therapeutic efficiency. However, studies on swine skin models show that some retinoids have low skin permeability. Thus, the association of innovative formulations with technological strategies involving physical permeation promoters can be employed to increase the permeability of this active, ensuring a targeting effect of the active. AIMS: In this study, it was proposed the development and evaluation of the release and permeation profile of liquid crystalline systems with retinoic acid polymeric microparticles under passive or iontophoretic diffusional conditions. METHODS: For this study, release, permeation, and diffusional characterization assays were employed using the Franz diffusion cell model, associating or not the cathodic iontophoresis. RESULTS: Retinoic acid was considered stable in front of the electric current of 0.5mA/cm2 , because it did not show significant degradation (with maintenance from 96.03% to 98.57%), indicating the viability of such agents to be applied with iontophoresis. Controlled release profile was evidenced for microencapsulated systems. Comparatively, formulations F1, F3, and F5 presented a significantly higher RA release profile when compared to formulations with retinoic acid microencapsulated. A significant increase was observed in the absolute amount of RA retained in the skin with cathodic iontophoresis in all proposed formulations (P < .01). The increase was up to two times in relation to the passive condition. CONCLUSIONS: The combination of iontophoresis technique with application of retinoic acid and microencapsulated retinoic acid allows the penetration of the active ingredient to deeper layers of the skin.

Target action of antioxidants using iontophoresis.

BACKGROUND: The use of antioxidants in applications for topical use seems promising, however, many studies must be performed to ensure processes and products that can effectively bring benefits to combat the action of free radicals in the skin. For topical antioxidants to be effective against free radicals from the skin, it is essential that the antioxidants compounds permeate the different skin layers, to reach deeper layers of the epidermis in active form and stay there for a sufficient time to cause the beneficial effects. AIM: This work aimed to evaluate the antioxidant action of formulations with phenolic compounds as well as to comprehend the skin retention profile of these actives. METHODS: The antioxidant potential was recognized with isolated phenolic acids (gallic, caffeic, and ferulic acid) or in combinations, using different in vitro methods (DPPH ABTS , FRAP , ß-carotene/linoleic acid system and ORAC). The skin retention study was performed through in vitro assay with Franz's diffusion cell associating, or not, the cathodic iontophoresis. RESULTS: Gallic acid showed the greatest antioxidant activity and was selected for a study of skin permeation following gel application to porcine skin, with or without cathodic iontophoresis. Gallic acid retention in deeper skin layers was promoted by iontophoresis, and increased skin antioxidant activity was detected after only 20 min of iontophoresis. The present study demonstrated the importance of polymeric gelling agents for optimizing the antioxidant activity. CONCLUSION: The cathodic iontophoresis represents a promising strategy to promote a target action of antioxidants in the skin.