![]() Petrolatum is the most effective classic occlusive moisturizer a minimum concentration of 5%, can reduce trans-epidermal water loss by more than 98%, with 170-times water vapor loss resistance as compared to olive oil. The most important materials are liquid paraffin and petrolatum. Petroleum is a mineral oil source consisting of complex hydrocarbons combination. Occlusives diffuse into the intercellular lipid domains, contributing to their efficacy. Occlusives have the most significant effect when applied to dampened skin by creating hydrophobic barrier over the skin contributing to the inter-corneocytes matrix. Mineral oil, petroleum jelly, beeswax, silicones, zinc oxide Urea, sorbitol, panthenol, glycerol, propylene glycol, hyaluronic acid, alpha hydroxy acids Oily application, cosmetically disagreeable, folliculitis (mineral oil), contact dermatitis (lanolin), acneiform eruptionįatty acids, fatty alcohols, cholesterol, squalene, pseudoceramides Prevention of contact dermatitis, xerosis, atopic dermatitis Routine skin care, dry and rough skin, papulosquamous skin disease Small molecular weight proteins, believed to aid skin rejuvenation by replenishing skin’s essential proteins Frequently used with other compounds which may retain the water contentĬonsist of oils and waxes, forming an inactive layer on the skin surface to physically block water evaporation from the skin (transepidermal water loss) Low molecular substances in majority, with capability to attract water into stratum corneum. Saturated & unsaturated hydrocarbons with variable length which improves skin barrier function, membrane fluidity and cell signaling, resulting in overall improvement of skin texture and appearance. 14 Loden 5 concludes that skin care products do not only stay inactively on the skin surface, but also penetrate to influence the skin’s structure and function. Skin mechanics change thereafter as increased hydration facilitate degradation of corneodesmosomes, preventing corneocytes accumulation, while promoting its continuity. Furthermore, moisturizer application smooths skin surface by filling spaces between partially desquamated skin flakes and restores the ability of the intercellular lipid bilayers to absorb, retain and redistribute water. 13 Moisturizers improves skin hydration and increases stratum corneum water content by directly providing water to the skin from their water phase and increasing occlusion to reduce trans-epidermal water loss, it also covers small skin fissures, provides a soothing protective film and protects skin from friction. Moisturizers improve skin barrier repair, maintain skin’s integrity and appearance by acting as humectants, emollients, and occlusives, each with its own mechanism of action. ![]() Dry skin signs appear when corneocytes accumulate on skin surface (when stratum corneum has less than 10% water content) and lose its continuity. In desquamation, corneodesmosomes are degraded by water-dependent hydrolytic agent, which work less efficiently in low moisture stratum corneum. natural moisturizing factor production is directly related to external humidity. Fifty percent of natural moisturizing factors are amino acids originating from keratinocyte protein filaggrin, the remaining are salts, including lactates, urea, and electrolytes. The natural moisturizing factor within corneocytes is a mix of hygroscopic molecules, which maintain and hold corneocyte’s hydration. ![]() Stratum corneum’s lipid bilayers act as moisture barrier and despite preventing many chemicals entry they are also means of entry for most topically applied substances. 11 Corneocytes are the stratum corneum’s physical barrier, contributing to elasticity when hydrated. 10 There are four key processes in stratum corneum formation and functioning: corneocyte, stratum corneum lipid, natural moisturizing factor, and desquamation. The structure of the stratum corneum is the pivotal factor in skin water flux, retention and overall moisturizing level. 10 Stratum corneum is an active membrane, described as a bricks and mortar model, where loss of intercellular lipids, forming the bilayers (eg, ceramides, cholesterol and fatty acids) will result in water barrier formation damage leading to dry skin. Epidermal water content is essential to prevent skin dryness and maintain plasticity. Water from deeper epidermal layers moves upward to hydrate stratum corneum cells and is then lost to evaporation. Impaired function leads to increasing trans-epidermal water loss associated with various kinds of dermatitis. ![]() The skin functions as a barrier, protecting underlying tissues from desiccation, infection, mechanical stress and chemical irritation. ![]()
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