Development and validation of an analytical method using High Performance Liquid Chromatography (HPLC) to determine ethyl butylacetylaminopropionate in topical repellent formulations

ABSTRACT Diseases caused by insects are frequent in poor countries, leading to epidemic scenarios in urban areas; e.g., Dengue, Zika and Chikungunya. For this reason, the development of a safe and efficient topical formulation is essential. Ethyl butylacetylaminopropionate (EB) is a mosquito repellent developed by Merck, which is used in products for adults, children and especially babies, due to its low allergenic potential. The aim of this work was to validate an analytical methodology to quantify EB in a new poloxamer-based formulation by high-performance liquid chromatography (HPLC). The quantification methodology was performed at 40 ºC using a Kromasil reverse-phase column (C18), with the dimensions of 250 x 4.6 mm. The mobile phase was acetonitrile:water (1:1) at a 1.0 mL/min flow-rate. The detector wavelength was set at 218 nm to detect EB. The methodology was considered validated since the results indicated linearity (R2>0.99), specificity, selectivity, precision and accuracy (active recovery between 98% and 102%). It also presented limits of detection and quantification of 0.255 µg/mL and 0.849 µg/mL, respectively. The present study demonstrated the EB vehiculated in poloxamer gel is promising as a new insect repellent formulation, since it could be quantified and quality control evaluated.

Promotion of cutaneous penetration of nifedipine for nanoemulsion

ABSTRACT This article reports the development and characterization of a nanoemulsion (NE) able to improve the cutaneous penetration of nifedipine. NE with nifedipine was development and characterized, presenting droplet size of 20 nm with low polydispersity index (IP<0.1), spherical shape without aggregation, pH compatible with typical skin levels and stability evaluated by seven months. In the permeation studies, a classical formulation based in an oil/water cream containing nifedipine was used for comparison with NE. Nanoemulsion promoted and improved the retention of nifedipine in the epidermis and dermis in relation to classical formulation. This promoting effect is related to the nanometric size of the droplets of the NE (20 nm), which give him a large superficial area, favoring the contact of the nanocarrier with the skin surface. The NE was efficient in promoting accumulation of nifedipine in the dermis, which is the site of vasodilation action. NE was not irritating according to the primary dermal irritation tests. NE is a promising release system to promote cutaneous penetration of nifedipine and can be used in the future in clinical trials to promote healing of lesions caused by peripheral vascular diseases.

In vitro and in vivo evaluation of efficacy and safety of photoprotective formulations containing antioxidant extracts

ABSTRACT Chronic exposure to solar radiation could contribute to premature skin aging and skin cancer. Skin presents its own antioxidant defense, however when defenses are out of balance, reactive oxygen species could damage biological structures. In the present work, an oil-in-water photoprotective emulsion was developed and Bauhinia microstachya var. massambabensis Vaz, Fabaceae, extracts at 1% (obtained by extraction with different solvents) were added to this emulsion. In vitro and in vivo efficacy and safety of the formulations were evaluated. Spectrophotometric methods and in vivo Colipa test were performed to evaluated efficacy of the formulations, through sun protection factor (SPF) determination and UVA protection factor assessment. To the in vitro safety assessment HET-CAM, CAM-TBS and Red Blood Cell tests were performed. Results showed that both extracts contributed to a higher in vivo photoprotection (SPF 18) when compared to the formulation without extract (SPF 13), this result could be attributed to the antioxidant activity of the plant extracts that act by capturing reactive oxygen species. Concerning safety, all formulations were considered non-irritant according to in vitro tests. Formulations containing extracts could be considered efficient and safe for cosmetic use since they presented higher sun protection factor and passed the toxicity tests.