The Effect of a Ceramide-Containing Product on Stratum Corneum Lipid Levels in Dry Legs
April 2020 | Volume 19 | Issue 4 | Original Article | 372 | Copyright © April 2020
Published online March 12, 2020
Zoe D. Draelos MD,a Nada H. Baalbaki PhD,b Shelby Cook MS,b Susana Raab BA MBA b, Gene Colón Esq.c
aDermatology Consulting Services, PLLC bL'Oréal Research and Innovation, Clark NJ cL'Oréal USA, Inc. (CeraVe), New York, NY
Roughly equimolar concentrations of ceramides, cholesterol, and free fatty acids arranged in lamellar sheets form the intercellular lipid barrier in the stratum corneum (SC). Intercellular lipid deficiencies, specifically ceramides, and barrier disruption are associated with many dermatologic conditions, including dry skin. This study explored the relationship between the improvement in the signs of dry skin and the amounts of ceramides in the SC by combining clinical observations with a biochemical analysis to quantify the level of SC intercellular lipids. The efficacy of a multilamellar vesicular emulsion (MVE), ceramide-containing moisturizing cream was evaluated in a randomized, investigator-blinded, split-leg study on female subjects with dry, itchy skin. The cream increased skin hydration and demonstrated an immediate and sustained reduction in the visible signs of dry skin and subject perceived sensory discomfort. Additionally, ceramide, cholesterol and free fatty acid levels in the SC significantly increased after 4 weeks of moisturizer application. Thus, the clinical effect of the ceramide-containing moisturizing cream on dry, itchy skin was accompanied by an increase in SC intercellular lipid levels. J Drugs Dermatol. 2020;19(4):372-376 doi:10.36849/JDD.2020.4796
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Ceramides have become important ingredients in moisturizers since they were first synthetically introduced 15 years ago. The addition of ceramides to moisturizer formulations was built on the concept that ceramide synthesis is the initiating event for barrier repair following damage.1 Barrier disruption characterizes many dermatologic conditions, including psoriasis, acne, eczema, atopic dermatitis, and rosacea, where the intercellular lipids have been either removed or poorly formed. These intercellular lipids are composed of roughly equimolar concentrations of ceramides, cholesterol, and free fatty acids arranged in lamellar sheets accounting for the barrier property of the epidermis.2
Ceramides are a complex group of sphingolipids composed of sphingosine bases in amide linkages with fatty acids.3 There are 9 major classes of free ceramides (Cer 1-9) and 2 major protein-bound ceramides covalently bonded to corneocyte protein envelopes (Cer A, Cer B).4 However, the nomenclature for synthetically derived ceramides has been updated for proper ingredient disclosure. The new INCI nomenclature for Ceramide 1, 3, and 6-II will be Ceramide EOP, NP, and AP. The "P" indicates the ceramide contains phytosphingosine, while the EO, N and A distinguish the type of fatty acid. Phytosphingosine-containing ceramides are often called phytoceramides since they can be derived from plants.
It has been demonstrated in atopic dermatitis, there is a decrease in ceramides 1 and 3, which has been associated with an increased skin susceptibility to irritants and increased transepidermal water loss (TEWL).5 These observations have been found in both lesional and nonlesional skin.6 In addition, it has been demonstrated that treatment with ceramide 1 increases skin barrier resistance against sodium lauryl sulfate induced damage.7
Traditional moisturizers create an environment for barrier repair by decreasing TEWL through occlusive agents, such as petrolatum, dimethicone, mineral oil, and botanical oils, in combination with humectants attracting water to the skin, such as glycerin, propylene glycol, and sodium PCA. However, therapeutic moisturizers attempt to deliver more benefit by addressing additional physiologic needs with the addition of ceramides, cholesterol, and fatty acids. In addition, synthetic skin identical ceramides 1, 3, and 6-II can be topically applied to attempt to reduce the skin susceptibility to irritants.8
However, dermatologists have questioned whether topically applied skin identical ceramides can be incorporated into the stratum corneum or whether they reside only on the skin surface, providing minimal physiologic benefit. This research attempted to understand the relationship between improvement in the signs and symptoms of dry skin and the amounts of ceramides in the stratum corneum of the lower leg. This was accomplished by combining clinical observations with a biochemical analysis attempting to document the presence of ceramides within the stratum corneum.