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Influence of excipients on moisturizing effect of urea
C Couteau1, L J M Coiffard, V Sébille-Rivain
1L.P.I.C., Faculty of Pharmacy, SMAB (EA 2160), University of Nantes, 1 rue Gaston Veil, 44035, Nantes Cedex, France. laurance.coiffard@univ-nantes.fr
Abstract:
Water is the most important molecule contained in the skin and is bound to the intracellular hygroscopic substances called natural moisturizing factors (NMF). The clinical characteristic of xerosis is rough and/or coarse skin. This anaesthetic alteration necessitates cosmetic products application. In this study, we tested the efficiency of urea incorporated into six different emulsions (O/W) and 10 different gels. Skin of 10 healthy women (20 to 45 years) was treated using 50 mg of emulsion or gel containing 5% of urea. A skin surface of 16 cm(2) was chosen in the area of the forearm. The gain in moisturizing was performed measuring the skin electrical capacity using a corneometer (Courage & Khazaka, model CM 825), one hour after treatment. Sodium carboxymethyl cellulose gel has the least moisturizing effect. On the other hand, the mixture of polyacrylamide and C13-14 isoparaffin polysorbate 85 can be a good vehicle in the treatment of skin dehydration. Adding various oils (6%) or collagen in aqueous solution does not improve the efficiency of the tested products. Moisturizing effect of gels (polyacrylamine with C13-14 isoparaffin polysorbate 85) is higher than the one of emulsions (L/H).
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Pore Transport and Ion-Pair Transport
Pore transport, also known as convective transport, is a process where small molecules like urea, water, and sugars rapidly cross cell membranes as though there were channels or pores in the membrane. Although direct microscopic evidence is limited but the concept of pores or channels is widely accepted based on physiological evidence. Despite the lack of direct microscopic...

