3–10% solutions are usually preferred, an aqueous spray containing 42% urea has been considered.
Lactic acid, a 12% component of dissolved solids in SC moisture, has skin hydration
properties, leading to its use in some body sprays. At higher levels, skin peeling may result.
Certain vitamins are beneficial, while others can be harmful. Vitamin A (all trans-retinol) is a
polyunsaturated alcohol and very irritating if applied directly to the skin. Instead, retinaldehde
or corresponding esters are preferred. The recommended daily average (RDA) is a mere 0.7 milligram.
Despite its beneficial prevention of dry skin pruritus on the molecular level, it has fallen
out of favor since larger skin treatments may induce embryo-teratogenicity and embryo-toxicity in
infants where mothers were exposed to retinoids during the first trimester of pregnancy.
Estrogen, iso-flavone and certain other compounds increase the potency of HA. Hydrocortisone
decreases it. Hydrophilic formulations containing zinc oxide (ZnO) and less effectively,
titanium oxide (TiO2) fine powders impair TEWL, but both become more potent and longer
term if humectants are incorporated in treatment formulas.
Market Appeal
Since reportedly about 90% of mature U.S. women are said to use skin moisturizers on a daily
basis, hundreds of marketers now offer products that extol humectancy and promise smooth,
healthy and attractive skin (pharmacies offer an oral treatment in the form of a tablet that advertises
a high level of dry skin control and even remission).
The skin is the largest and perhaps the second most complex body organ. There are eleven
skin types in males and twelve in females. The skin contains many hundreds of chemical compounds,
for instance, aliphatic alcohols up to at least C44H87OH. Health and cosmetic challenges
have created a huge skin care market, now growing at a unit rate of about 3.4% year-over-year.
Some skin care products contain over 30 ingredients and make label claims such as “Contains
Seven Moisturizing Agents.” Aerosol sprays, foams and pump-lotions are all well represented.
The future looks bright.” SPRAY
November 2017 SPRAY 33