When the Stratum Corneum moisture content of skin drops
below 10%, it is perceived as dry. A moisturizer is any material
that helps skin retain moisture.
The challenge in developing a great moisturizer is to accomplish optimum moisturization while achieving a high level of consumer acceptance. This is especially important for facial moisturizers that must be formulated to be non-greasy and fast absorbing. Facial skin isn’t as dry as the hand and the lower leg area and doesn’t require the use of high concentrations of humectants like those found in hand and body lotions. Facial skin however is more sensitive and prone to irritation requiring good barrier building technology.
A good moisturizing base should be the foundation for all antiaging skin care formulations. Good moisturizers can provide the following skin benefits:
- Reduction in dry, itchy skin
- Reduced skin irritation
- Improved wound healing. Good moisturizers can accelerate wound healing by up to 25%
- Improved skin elasticity, translucency
- Reduced fine lines and wrinkles
- Improved skin barrier function
- Improved liquid foundation application
- Longer lasting self-tanning color (Dihydroxyacetone (EU) based products)
Moisturizer Formulating Strategy
Good moisturizers are a blend of the right barrier building, TEWL reducing lipids combined with a good humectant delivery system. Humectants (EU) need to both penetrate into and persist on top of the Stratum Corneum for maximum effectiveness. The product film needs to be substantive and persist on skin over time to accomplish this. This is why high Corneometer readings don’t necessarily guarantee good dry skin reduction efficacy.
To improve efficacy, develop a multi-lamellar liquid crystal based oil in water emulsion. Good options include:
- Net LCS-PF (Caprylic/Capric Triglyceride (EU), Hydrogenated Lecithin (EU), Cetyl Alcohol (EU), Stearyl Alcohol (EU), Behenyl Alcohol (EU), Phytosterol, Glyceryl Stearate Polyglyceryl-10 Myristate, Tocopherol (EU))
- Biophilic H (Hydrogenated Lecithin (EU), C12-16 Alcohols, Palmitic Acid-Lucas Meyer (EU))
Another important step in the strategy is to develop an acute and chronic treatment approach that provides immediate skin benefits and also helps stimulate the production of natural barrier building substances such as epidermal lipids and NMF.
The use of Aquaporin stimulants such as Aquaporin 3 (AQP3) plays a major role in regulating the moisture content and glycerin transport in skin. This includes:
- Caffeine has been shown to increase both protein expression and glycerin transport in vitro and improvement dry skin in vivo.
- Saliporine 8 (Barnet Products-Caprylic/Capric Triglyceride and Salicornia herbacea Extract) has been shown to increase Aquaporin 8 levels in skin. This leads to an increase production of filaggrin/urea and NMF (natural moisturizing factors). An in vivo study using 1% Saliporine demonstrated a 25% increase in urea and a 6000% increase in hydration versus placebo after 28 days of use.
- Synova DOI (Sytheon- Dioctanoyl Isosorbide) is an emollient claimed to improve skin barrier function by up regulating Aquaporin 3 and key tight junction and desmosome genes.
Your product should have a PH around 4-4.5. This helps the formation of epidermal lipid bilayers and assists in preserving the formulation. Additionally, the use of cosmetic antiirritants like Panthenol (EU) to reduce skin irritation and help improve the skin barrier function.
One final step is to keep emulsifiers to a minimal. Many can disrupt the barrier function and cause skin irritation. Lecinol S10 (Hydrogenated Lecithin- Nikko Chemical/Barnet Products) and Cetearyl Glucoside (Tego Care CG 90-Evonik (EU)) are good choices.
- Glycerin (EU)- is the most widely used humectant and is considered to be the industry bench mark for skin moisturization
- Hydrovance (Akzo (EU)-Hydroxyethyl Urea)-It has a similar performance profile as glycerin with a significantly better sensory profile. Synergism with Glycerin is also claimed
- Cola Moist 200C (Colonial Chemical- Hydroxypropyl Bis-Hydroxyethyldimonium Chloride), a good substantive humectant
- Pentavitin (Saccharide Isomerate-DSM (EU)) is a carbohydrate complex identical to the natural moisturizing factor found in skin. It has been shown in vivo to bind to free amino groups of lysine resulting in a sustained moisturizing effect
- Isostearyl Isostearate Schercemol™ 1818 Ester (EU) was shown to significantly improve skin hydration by modifying skin lipid crystallinity
- Isopropyl Isostearate Schercemol™ 318 Ester (EU) was shown to significantly reduce TEWL more effectively then Petrolatum by modifying skin lipid crystallinity
- Petrolatum (EU)- The key industry benchmark occlusive emollient
- Cetyl Ricinoleate (Naturchem CR-Vertellus Performance Materials) (EU), has been shown to have excellent dry skin reduction efficacy
Skin barrier-building materials (stimulate the natural production of skin lipids)
- Niacinamide (EU)- In vivo studies have demonstrated that topical Niacinamide increases Stratum Corneum lipids, resulting in a decrease in TEWL and an increase in skin surface water content.
- L-Lactic acid was shown to increase Stratum Corneum Ceramide levels by 38%. L-Lactic acid was applied to the volar forearm twice a day for four weeks. The watch out is potential facial stinging.
- SymRepair 100 (Hexyldecanol (EU), Bisabolol (EU), Cetylhydroxyproline Palmitamide, Stearic Acid, Brassica Campestris (Rapeseed) Sterols-Symrise) has been clinically shown to protect and repair skin barrier function at .1%. Cetylhydroxyproline Palmitamide is a synthetic Ceramide that was shown to perform as well as natural ceramides and works synergistically with Bisabolol.
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