Effect of lipid-containing, positively charged nanoemulsions on skin hydration, elasticity and erythema--an in vivo study.Int J Pharm. 2006 Jan 13; 307(2):232-8.IJ
Dry skin and other skin disorders such as atopic dermatitis are characterized by impaired stratum corneum (SC) barrier function and by an increase in transepidermal water loss (TEWL) leading to a decrease in skin hydration. The possibility that dermatological and cosmetic products containing SC lipids could play a part in the restoration of disturbed skin barrier function is of great interest in the field of dermatology and cosmetics. The aim of the present study was to evaluate the effect of positively charged oil/water nanoemulsions (PN) containing ceramide 3B and naturally found SC lipids (PNSC) such as ceramide 3, cholesterol, and palmitic acid on skin hydration, elasticity, and erythema. Creams of PNSC were compared to PN creams, to creams with negatively charged o/w nanoemulsion and SC lipids (NNSC) and to Physiogel cream, a SC lipid containing formulation, which is already on the market. The formulations (PN, PNSC, and NNSC) were prepared by high-pressure homogenization. After adding Carbopol 940 as thickener, particle size and stability of the creams were not significantly changed compared to the nanoemulsions. The studies were carried out on three groups, each with 14 healthy female test subjects between 25 and 50 years of age, using Corneometer 825, Cutometer SEM 575 and Mexameter 18 for measurements of skin hydration, elasticity, and erythema of the skin, respectively. The creams were applied regularly and well tolerated throughout the study. All formulations increased skin hydration and elasticity. There was no significant difference between PNSC and Physiogel. However, PNSC was significantly more effective in increasing skin hydration and elasticity than PN and NNSC indicating that phytosphingosine inducing the positive charge, SC lipids and ceramide 3B are crucial for the enhanced effect on skin hydration and viscoelasticity.