Structural characterization and in vivo evaluation of retinyl palmitate in non-ionic lamellar liquid crystalline system.

Carrier systems for lipophilic drugs, such as the liquid crystalline systems (LCS) have been extensively studied to improve effect and selectivity. Retinyl palmitate (RP) is widely used in pharmaceutical and cosmetics products to improve the skin elasticity. The aim of this study was the development, characterization and the in vivo effectiveness of RP in non-ionic LCS structures. LCS containing polyether functional siloxane as oil phase, silicon glycol copolymer as surfactant and water in the ratio 30:10:60, with and without RP were studied. The results of the polarized light microscopy, small-angle X-ray scattering and rheology analysis indicated the presence of typical LCS structures with lamellar arrangement. Regardless of the presence of RP, the rheological studies showed the pseudo plastic behavior of the systems. However, highest hysteresis area was verified when comparing the system in the presence and in the absence of RP. Stability study SAXS monitored, carried out up to 30 days in various storage temperature conditions (25±2 °C, 37±2 °C and 5±2 °C) demonstrated the great structural stability of the LCS systems. The in vivo effectiveness analysis suggests that the RP-loaded LCS provided a significant reduction of the orbicular wrinkles in human volunteers (P=0.048).

Avaliação da interação de compostos ativos hidratantes com modelo de biomembrana de Crotalus durissus por meio de calorimetria exploratória diferencial e espectroscopia RAMAN / Study of the interaction of moisturizers with a Crotalus durissus biomembrane by differential scanning calorimetry and RAMAN spectroscopy

O objetivo foi verificar as alterações no estrato córneo em modelos alternativos de membrana após a aplicação de ativos hidratantes envolvendo métodos biofísicos. O modelo de biomembrana utilizado foi a muda de pele de Crotalus durissus e os ativos hidratantes foram: uréia, silício orgânico, extrato vegetal de Imperata cylindrica, reação de xilitol e glicose e componentes de NMF. Os resultados da avaliação das alterações do modelo por meio de Espectroscopia Raman com Transformada de Fourier sugerem que os ativos hidratantes confirmam segurança necessária, pois não alteraram de forma acentuada a estrutura do estrato córneo. Utilizando-se Calorimetria Exploratória Diferencial pode-se indicar que a solução de silício orgânico e o gel hidrofílico com uréia apresentaram melhor poder hidratante.

The objective of this research was to use biophysical techniques to investigate the alterations induced in a biomembrane model of the stratum corneum by the application of moisturizers. The biomembrane was obtained from the skin shed by the rattlesnake Crotalus durissus and the active moisturizing compounds were: urea, dimethylsilanol hyaluronate, Imperata cylindrical plant extract, carbohydrates and natural moisturizing factors (NMF components). Results from FT-Raman spectroscopy suggested that the moisturizers were safe, since they did not promote modifications in the structure of the stratum corneum. Differential scanning calorimetry results indicated that the solution containing the organic silicon compound and the gel with urea showed the best hydrating effects on the stratum corneum.

Avaliação da estabilidade físico-química de emulsão acrescida de uréia dispersada, ou não, em propilenoglicol / Evaluation of the physicochemical stability of emulsion containing urea, added directly or premixed in propylene glycol

Normalmente uma formulação pode ser manipulada de diversas maneiras, devendo-se sempre optar pela técnica que forneça o produto mais estável e homogêneo. Alguns farmacêuticos a fim de facilitar e acelerar a manipulação dispersam a uréia em propilenoglicol antes de proceder a homogeneização da mesma no veículo, enquanto outros profissionais acreditam que essa técnica pode ocasionar instabilidade física no produto final e por isso acrescentam o veículo diretamente na uréia. Logo, o objetivo deste estudo foi analisar o comportamento reológico e a estabilidade física de formulações acrescidas de 10% de uréia manipuladas com, ou sem, a adição de propilenoglicol. Foi realizado o estudo de Estabilidade acelerada, com duração de 180 dias. As formulações foram armazenadas em temperatura ambiente (25ºC±2), geladeira (5ºC±2) e estufa (37ºC±2) e as leituras foram feitas nos tempos 24 horas (T1), 15 dias (T15) e 180 dias (T180), onde foram analisadas as características organolépticas, teste de centrífuga, determinação do pH, viscosidade e comportamento reológico. Os resultados obtidos neste estudo mostraram que a presença do propilenoglicol melhorou a estabilidade física da emulsão acrescida de uréia, a longo prazo.

Normally, an emulsion can be prepared in several ways, the method of choice invariably being the one that provides the most stable and homogeneous product. Some pharmamacists, in order to facilitate and accelerate the manipulation, disperse the urea in propylene glycol before proceeding to its homogenization in the vehicle, while others believe that this method can lead to physical instability in the final product and for that reason they add the vehicle directly to the urea. Therefore, the aim of this study was to analyze the rheological behavior and the physical stability of formulations containing 10% urea, prepared with, or without, the prior addition of propylene glycol to the urea. An accelerated stability test was carried out over a period of 180 days. The formulations were stored at room temperature (25±2ºC), refrigerated (5±2ºC) and incubated at blood temperature (37±2ºC) and assessed after 24 hours (T1), 15 days (T15) and 180 days (T180), when the organoleptical characteristics, pH, viscosity and rheological behavior were recorded, along with data from the centrifuge test. The results showed that premixing the urea in propylene glycol improved the physical stability of the emulsion plus urea, in the long run.