Nanovesicle-based formulations for photoprotection: a safety and efficacy approach.

Vesicular nanosystems are versatile and they are able to encapsulate actives with different solubilities, such as lipophilic and hydrophilic compounds. The most well-known vesicular nanosystems are liposomes and niosomes, the last one is formed by non-ionic surfactants. In the present work, we developed photoprotective niosomes containing sunscreens (octyl methoxycinnamate, diethylamino hydroxybenzoyl hexyl benzoate and phenylbenzimidazole sulfonic acid), non-ionic surfactants, cholesterol and stearylamine (positive-charged lipid). Studies based on dynamic light scattering techniques, entrapment efficiency and morphology by transmission electron microscopy were performed to characterize the niosomes. In addition, rheology, pH, in vitro sun protection factor (SPF) efficacy and toxicity and in vivo and in vitro safety were determined for the niosome formulations F-N1 and F-N2. The mean sizes of N1 and N2 were 168 ± 5 nm and 192 ± 8 nm, respectively, and their morphologies were spherical, unilamellar and with an entrapment efficiency of more than 45% for each sunscreen. Both formulations, F-N1 and F-N2 presented characteristics of pseudoplastic non-Newtonian fluids, showing declining viscosity with increasing shear rate applied. SPF values were considered satisfactory, 34 ± 8 for formulation F-N1 and 34 ± 5 for F-N2. The formulations did not present toxicity when tested in macrophages and the pH was compatible with skin, which minimizes allergies. The in vitro safety assay showed lipophilic sunscreens greater affinity for the epidermis, since this layer contains natural lipids. In vivo safety assay suggests that the increased skin retention of N2 is directly correlated with the positive charge of stearylamine. Stable photoprotective niosomes were obtained and were shown to be promising nanostructures to be used against solar radiation.

Multifunctional photoprotection: corrective makeup for cutaneous dyschromias

The aim of this study was to develop and evaluate a corrective and photoprotective makeup for patients with dyschromias. An emulsion was prepared and pigment mixtures were incorporated in the formulation, producing five shades of corrective makeup: BEIGE (I, II, III), BRONZE and TAN. The sun protection factor (SPF) and UVA/UVB ratio of the corrective makeup were determined using spectrophotometry with a Labsphere® analyser. The spreadability, occlusivity, stability, and photostability of the photoprotective formulations were also evaluated. For all formulations there was no statistical difference among them (p > 0.05) in terms of spreadability, occlusivity and SPF. They were considered to be photostable under solar radiation, with variations in SPF value and UVA/UVB ratio lower than 20%. The corrective makeup presented average-to-high UVB photoprotection and broad spectrum photoprotection. After 90 days, pH, density and SPF values showed no significant differences among formulations (p>0.05). All corrective makeup presented separation of the pigments, however, they returned to a homogeneous aspect and to the original color shade after shaking. The corrective makeup presented a fine texture, little brightness, and a homogeneous, dry-to-the-touch aspect. This work may benefit patients with dyschromias, improving their quality of life, besides promoting photoprotection and covering the skin blemishes