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This study aimed to develop microemulsions (MEs) containing α-bisabolol for the topical treatment of cutaneous leishmaniasis (CL). Initially, pseudoternary phase diagrams were developed using α-bisabolol as the oil phase, Eumulgin® CO 40 as the surfactant, Polymol® HE as the co-surfactant, and distilled water as the aqueous phase. Two transparent liquid systems (TLS) containing 5% of α-bisabolol were selected and characterized (F5E25 and F5EP25). Next, skin permeation and retention assays were performed using Franz cells. The interaction of the formulation with the stratum corneum (SC) was evaluated using the FTIR technique. The cytotoxicity was evaluated in murine peritoneal macrophages. Finally, the antileishmanial activity of microemulsions was determined in promastigotes and amastigotes of L. amazonensis (strain MHOM/BR/77/LTB 0016). As a result, the selected formulations showed isotropy, nanometric size (below 25 nm), Newtonian behavior and pH ranging from 6.5 to 6.9. The MEs achieved a 2.5-fold increase in the flux and skin-permeated amount of α-bisabolol. ATR-FTIR results showed that microemulsions promoted fluidization and extraction of lipids and proteins of the stratum corneum, increasing the diffusion coefficient and partition coefficient of the drug in the skin. Additionally, F5E25 and F5EP25 showed higher activity against promastigotes (IC 50 13.27 and 18.29, respectively) compared to unencapsulated α-bisabolol (IC 50 53.8). Furthermore, F5E25 and F5EP25 also showed antileishmanial activity against intracellular amastigotes of L. amazonensis, with IC 50 50 times lower than free α-bisabolol and high selectivity index (up to 15). Therefore, the systems obtained are favorable to topical administration, with significant antileishmanial activity against L. amazonensis promastigotes and amastigotes, being a promising system for future in vivo trials., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

The present work aimed to evaluate different Liquid Crystal Mesophases (LCM) as transdermal drug delivery systems (TDDS) for nifedipine (NFD), a lipophilic drug model. The formulations composed of water, Citrus sinensis essential oil (CSEO), PPG-5-CETETH-20, and Olive oil ester PEG-7 were obtained and characterized by polarized light microscopy (PLM), rheology, small-angle x-ray scattering (SAXS), Fourier transform infrared coupled with an attenuated total reflection accessory (FTIR-ATR) and in vitro assays: bioadhesion, drug release, skin permeation, and retention tests. As a result, changes in component proportions led to several transparent viscous systems with an anisotropic profile. PLM and SAXS proved the presence of lamellar (S1), hexagonal (S3), and lamellar + hexagonal (S2) LCM, and rheology showed a high viscoelasticity profile. LCMs were able to adhere to the skin, and S2 achieved higher adhesion strength. NFD (5 mg/mL) has not modified the organization of LCMs. Results also showed that S3 promoted higher permeation and retention and higher disorganization of stratum corneum lipids, which is the main permeation-enhancing mechanism. Thus, the formulations obtained can carry and improve drug delivery through the skin and are promising TDDS for lipophilic drug administration, such as NFD., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

The objective of this study was to obtain optimized nanostructured lipid carriers (NLC) functionalized with chitosan containing chloroaluminum phthalocyanine (ClAlPc) as a photosensitizer. Initially, the optimization of the preparation method of the NLC was performed, where the influence of different surfactants such as PVA and Tween 80, as well as different solid lipids such as stearic acid and Glycerol Monostearate (GM) was evaluated. The formulation containing GM and PVA (NLC10) was considered promising. Following, by the adsorption method (NLC10q), the formulation was functionalized with chitosan and characterized. NLC10 and NLC10q presented sizes of 131.5 and 231.5 nm, and ZP of -24.30 and + 19.96 mV, respectively. The encapsulation efficiency of NLC10q was 96 %, higher than NLC10 (79 %). The formulations were able to promote significant cutaneous retention of ClAlPc, after 2 h and 4 h of the study, and showed to be non-toxic to fibroblasts (biocompatible). PDT in BF16-F10 melanoma resulted in reduced cell viability to 70 % and 50 % for NLC10 and NLCq, respectively. In view of the results obtained, NLC showed to be promising in the treatment of skin cancer through PDT. NLC10q showed higher encapsulation efficiency and stability than NLC10, but, contrary to what was expected, it presented lower photodynamic efficiency., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

UV radiation can cause damages, such as erythema, skin photoaging, and carcinogenesis. The adoption of protective measures against sun exposure is essential to prevent these damages, and the interest in using natural substances as an alternative for photoprotection is growing. Thus, hesperetin with antioxidant, anti-inflammatory, and anticancer properties is a promising substance to be used with photochemopreventive action and to protect the skin from damage induced by UV radiation. Therefore, the present study aimed to develop a topical formulation based on AAMVPC gel containing hesperetin and evaluate its photoprotective effect on the skin of rats exposed to UVA-UVB radiation. The animals were submitted to the irradiation protocol UVA-UVB, and at the end, erythema, lipid peroxidation, and activity of the antioxidant enzyme catalase and superoxide dismutase were evaluated. Additionally, it evaluated the activity of myeloperoxidase and histological changes. The formulation presented a rheological and spreadability profile suitable for cutaneous application. In vivo results demonstrated that the topical formulation of AAMVPC gel containing hesperetin at a concentration of 10% protected the skin from damage induced by UVA-UVB radiation, with the absence of erythema, lipid lipoperoxidation, and inflammation (low myeloperoxidase activity), and increased catalase and superoxide dismutase activities. The morphology and architecture of the dermo-epidermal tissue of these animals were like those observed under normal conditions (non-irradiated animals). Thus, the results showed that hesperetin was able to protect the animals' skin against UV radiation-induced skin damage and the protection mechanisms may be related to the antioxidant and anti-inflammatory properties of this natural product., (© 2022. The Author(s), under exclusive licence to American Association of Pharmaceutical Scientists.)

This study aims to evaluate the influence of the phase behavior of microemulsions in the transdermal administration ("spot-on") of ivermectin, an antiparasitic drug widely used in the treatment of endoparasites and ectoparasites in dogs. In this regard, pseudoternary phase diagrams composed of water (aqueous phase), isopropyl myristate (oil phase), tween 80 (surfactant) and labrasol (cosurfactant) were obtained in a different surfactant: cosurfactant (S:CS) ratios. S:CS in 1:3 ratio presented a larger region of microemulsion formation and three microemulsions were selected from it and characterized. Subsequently, in vitro permeation and retention studies were conducted using canine skin as membrane. SAXS, rheology and conductivity data were employed to confirm the phase behavior of the microemulsions (w/o, bicontinuous or o/w). The cutaneous permeation and retention tests showed that the w/o microemulsion, followed by bicontinuous microemulsion, resulted in a higher amount of drug permeated through canine skin, suggesting better transdermal permeation. On the other hand, o/w microemulsion resulted in a higher amount of drug accumulated into the skin, suggesting better topical activity. Thus, it can be concluded that phase behavior of microemulsions influenced the drug permeation in the canine skin differently from other animal models. Microemulsions, especially w/o and bicontinuous, can be promising vehicles regarding the transdermal delivery of ivermectin., (Copyright © 2020 Elsevier Ltd. All rights reserved.)