Principles of Moisturizer Product Design

January 2019 | Volume 18 | Issue 1 | Supplement Individual Articles | 89 | Copyright © January 2019

Christine Lee PhD,a John Bajor PhD,a Teanoosh Moaddel PhD,a Vivek Subramanian PhD,a Jian-Ming Lee PhD,a Diana Marrero MS,a Sheila Rocha MS,a Michael D. Tharp MDB

aUnilever Research & Development, Trumbull, CT bPalm Harbor Dermatology, Tampa, FL

fig9fig11logical therapeutic benefits and is often included in many good moisturizers.Niacinamide stimulates ceramide synthesis,13 reduces hyper-pigmentation,14,15 provides anti-inflammatory and anti-bacterial benefits,16 and contributes to anti-aging benefits like appearance of facial fine lines and wrinkles as proven at the concentrations used in the products (roughly 3%). One potential side effect of products containing niacinamide is flushing, particularly in consumers of Asian descent. The culprit ingredient is niacin, which is another form of vitamin B3 and can occur as a contaminant if the quality of the raw material is not properly controlled. Manufacturers of quality topical products know to screen raw materials for this contaminant.Alpha Hydroxy Acid (AHA) Alpha hydroxy acids (AHAs) are a class of organic carboxylic compounds including naturally-derived glycolic acid, lactic acid, malic acid, citric acid, and tartaric acid (Figure 9).17 AHAs have been used at various concentrations to enhance desmosomes resolution and stimulate desquamation, with positive benefits for the epidermis and dermis.18,19,20 At lower concentrations (5-10%), AHAs are available in over-the-counter products that can be used daily for improved barrier function and to improve the appearance of skin related to sun-damage, wrinkling, and hyperpigmentation benefits. At higher concentrations (20-70%), AHAs are used as chemical peels by dermatologists, beauty, and health spas.18 PPARs Peroxisome proliferator-activated receptors (PPARs) are well recognized for their effects on skin barrier development and maintenance,21,22 and on increasing keratinocyte differentiation.23,24,25 They enhance the production of barrier important lipids such as ceramides and fatty acids,26,27 and increase epidermal thickness and filaggrin synthesis leading to anti-aging benefits such as reduction in appearance of overall photodamage, mottled hyperpigmentation, and fine lines and wrinkles.28, 29 PPAR ligands are often naturally occurring unsaturated fatty acids such as conjugated linoleic acid (CLA). Such compounds are unstable, rapidly oxidize when exposed to air, and lose efficacy. Hence, historically, PPAR ligands have required the use of airless pack for stability leading to a higher cost product. In 2015, Unilever successfully introduced 12-hydroxy stearic acid (12-HSA) as a stable, gentle, and inexpensive PPAR ligand for the mass market (Figure 10). 12-HSA contains no unsaturated bonds obviating the need for high cost, airless packaging.Vitamins C and E The skin barrier is altered when exposed to external oxidative stresses such as UV irradiation and pollution.30 Vitamin C (ascorbic acid) and E (α-tocopherol) are two of the most important antioxidants to protect skin from these external oxidative stresses. Although these are powerful ingredients, vitamins C and E are extremely unstable upon exposure to air. More stable forms of these vitamins like magnesium ascorbyl phosphate and vitamin E acetate are available; however, these need to be absorbed and converted into the active form within the skin. It is important to recognize that not all vitamin C and E formulas have similar physiological activities active.Hyaluronic Acid (HA), a disaccharide polymer (Figure 11), is an integral component of the extracellular matrix where it plays