INTRODUCTION
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.
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.
