Perspectives of topical formulations for melasma.

Melasma is acquired hyperpigmentation that mainly affects the face, can cause negative changes in self-esteem, and mostly affects women. Treatment is difficult, and different drugs can be used in mono or combination therapy. In this article, we present a brief overview of melasma, how to evaluate it, and a synthesis of the most commonly used topical therapies and their indications, including sunscreens, pharmacological agents, and plant extracts. Hydroquinone (4%) in monotherapy or combined with corticosteroids (dexamethasone and fluocinolone acetonide) and retinoids (tretinoin); arbutin (1%); methimazole (5%); kojic (2%), azelaic (20%), and tranexamic (5%) acids are the pharmacological agents that stand out. Correct application of these substances determines a variable improvement in melasma but often causes adverse reactions such as erythema, itching, and burning at the application site. Vitamin C can contribute to the reduction of melasma and have little or no adverse effects while sunscreens are normally used as coadjuvant therapies. In conclusion, we have compiled specific topical therapies for treating melasma and discussed those that are the most used currently. We consider it important that prescribers and researchers evaluate the best cost-benefit ratio of topical therapeutic options and develop new formulations, enabling efficacy in the treatment with safety and comfort during application, through the reduction of adverse effects.

Comparative sensory and instrumental analyses and principal components of commercial sunscreens.

BACKGROUND: The initial contact of consumers when choosing sunscreens is through the trademark, packaging, perfume, and tactile feeling of the product, outlining the popular practice of sensory science. AIMS: To describe the sensory and physical-mechanical profile of commercial sunscreens through sensory and instrumental analyses related to principal component analysis (PCA). METHODS: Seven commercial sunscreens available on the Brazilian market and with a solar protection factor (SPF) of 30 were evaluated. Physical-mechanical profiling (rheological and textural analyses) was conducted by a trained panel, followed by sensory profile characterization and descriptive analysis. The results were assessed using the Spearman correlation coefficient and PCA. RESULTS: The correlation or lack thereof of the instrumental parameters with most of the sensory aspects was demonstrated using the Spearman coefficient. PCA enabled us to identify the nature of the dissimilarities among the samples. CONCLUSIONS: The obtained results highlight the importance of descriptive sensory analysis in the research and development of sunscreens, evidencing the significance of precisely informing the products' formulation in order to be chosen by the consumer.

Synthesis and characterization of nanostructured lipid-poloxamer organogels for enhanced skin local anesthesia.

The aim of this study was to synthesize a novel drug delivery system using organogels (ORGs) and characterize its physicochemical properties, in vitro and ex vivo permeation abilities, cytotoxicity and in vivo local anesthetic effects. The ORG formulations contained a mixture of oleic acid-lanolin (OA-LAN), poloxamer (PL407), and the commonly used local anesthetic lidocaine (LDC). The main focus was to evaluate the impact of LAN and PL407 concentrations on the ORG structural features and their biopharmaceutical performance. Results revealed that LDC, OA, and LAN incorporation separately shifted the systems transitions phase temperatures and modified the elastic/viscous moduli relationships (G'/G″ = ~15×). Additionally, the formulation with the highest concentrations of LAN and PL407 reduced the LDC flux from ~17 to 12 µg·cm-2·h-1 and the permeability coefficients from 1.2 to 0.62 cm·h-1 through ex vivo skin. In vivo pharmacological evaluation showed that the ORG-based drug delivery system presented low cytotoxicity, increased and prolonged the local anesthetic effects compared to commercial alternatives. The data from this study indicate that ORG represent a promising new approach to effectively enhance the topical administration of local anesthetics.