Development of topical hydrogels containing genistein-loaded nanoemulsions.

This article describes the development of topical hydrogels containing genistein-loaded nanoemulsions, obtained by means of spontaneous emulsification. This procedure yielded monodisperse nanoemulsions in a sub 250 nm range exhibiting negative zeta-potential and low viscosity. The formulations were incorporated into acrylic-acid hydrogels in order to have their viscosity adjusted for topical application. The semisolid formulations exhibit non-Newtonian pseudoplastic behavior. The skin permeation/retention of genistein from formulations was carried out using porcine ear skin mounted in Franz diffusion cells under sink conditions. The results showed a slow flow of genistein through the skin. Higher amount of genistein was detected into the skin from the formulation composed by medium chain triglycerides as oily core when compared to the octyldodecanol one. The overall results show that hydrogels containing genistein-loaded nanoemulsions could be considered as a promising formulation to delivery isoflavones into the skin.

Validation of an LC method to determine skin retention profile of genistein from nanoemulsions incorporated in hydrogels.

Recent studies have shown the effect of soy isoflavones in preventing skin photoaging and photocarcinogenesis, especially for genistein (GEN). Nanoemulsions have been proposed as a delivery system for GEN administration due to the low water solubility of this isoflavone. This article describes the validation of an isocratic liquid chromatography method to determine GEN in porcine ear skin layers from nanoemulsions before and after incorporation into hydrogels. The analyses are performed on a reversed-phase C18 column using a mobile phase composed of methanol-water (70:30, v/v) under acid conditions (at pH 3.0) and UV detection at 270 nm. The method is linear in the range of 0.1-10 µg/mL (r(2) > 0.999) in the presence of skin extracts. The low limit of quantitation is estimated as 0.1 µg/mL. No interferences from formulation excipients or skin layer compounds are detected. The RSD values for intra- and inter-day precision are lower than 15%. Recovery ranged from approximately 90% to 110%. The method is applied to estimate GEN retention in the skin from formulations using Franz diffusion cells. The highest amount of GEN is detected in the epidermis (185 µg/cm(2)). In conclusion, the method proved to be specific, precise, and accurate in determining GEN amounts from formulations in skin retention studies.

A simple and rapid method to assess butenafine hydrochloride in skin samples and a comparative cutaneous retention study of two marketed formulations.

A new method for the quantification of butenafine hydrochloride (BTF) present in the main skin layers was validated and a study conducted with the aim of analyzing the penetration and/or the permeation of the drug. The quantification was performed by liquid chromatography. To evaluate the specificity of the method, the influence of the components of the skin was analyzed, as well as the skin in contact with the excipient ingredients. Linearity was assessed with concentrations in the range of 0.1-10 µg/mL (r(2) = 0.9999) and ANOVA showed non-significant linear deviation (p > 0.05). Adequate results were obtained for repeatability, intra-day precision and accuracy. The obtained values for the limit of quantification and the limit of detection were 68.4 and 17.7 ng/mL, respectively. Also, a comparative study of BTF cutaneous penetration through porcine skin was performed applying two different formulations: Tefin, present in the Brazilian market, and Lotrimin Ultra(®) , available in the American market. No statistical difference was found in the skin (epidermis plus dermis) and in the epidermis (p > 0.05), although in the dermis the difference was significant (p < 0.05). During the experimental period (8 h), no drug permeation from either formulation was detected in the receptor fluid.