rent incident frequency in the
U.S. population.
In addition to this partial
listing, there are incidents
such as cuts, bruises, animal
and insect bites, burns, allergen
Dermatitis, also known as eczema, is a group of diseases that results in inflammation of the skin.
contacts, UV-A and UV-B radiation, defatting or corrosive chemical contacts and other exposures
that can damage the functionality and appearance of skin. We have learned how to cope with at least
some of these challenges. Visits to a dermatologist every six months or so are important in both identifying
and coping with certain skin problems. Offending cancerous sites can be treated by cryotherapy
(nitrosol freezing) or surgical procedures. For the very common dry skin problems, daily treatment with
formulated emollients or moisturizers can be very beneficial. Surveys suggest that over 90% of women and
many men utilize these products on a regular basis.
Functions of moisturizers & emollients
The terms “moisturizer” and “humectant” imply products that increase the hydration of the SC, making it
softer and more flexible (marketers often claim “making it clear”). The signal word “moisturizer” is more
immediately understood and persuasive to consumers than other terms, so it often has a dominant role on
product labeling. The more medical term “emollient” is less conspicuous, although it connotes a broader
set of benefits.
An emollient is included in water-based formulations, such as oil-in-water (o/w) or water-in-oil (w/o)
emulsions, lotions, ointments and creams. It has three primary functions: by holding the water portion
against the treated skin, the SC is hydrated; the emollient acts to reduce the trans-epidermal water loss
(TEWL) rate by forming a lipid layer on the skin
surface (the occlusive action of the product enhances
hydration of the SC); and lastly, emollients
can effectively bind water rising from deeper parts
of the dermis. The result of daily or twice-daily
applications is that dry skin (xerodermis), psoriasis
and some other skin problems are mitigated or
even eliminated. The skin looks smoother, with
reduced wrinkling. Corneocyte flaking is suppressed
and the skin becomes more flexible and less prone
to possible fissuring at stress locales.
Clinically, a moisturizer does not form a lipid film
on the dermal surface to reduce the TEWL. It operates
within the skin to conserve moisture, utilizing
processes only partly understood. The most important
example is propylene glycol (PPG), found
in numerous skin care formulations. Monotherapy
of emollients and moisturizers is historic, but never
utilized in modern multi-functional products. As a
consequence, the term moisturizer (or humectant)
has taken on a broader denotation, being applied
to complex formulations of multi-therapeutic prod-
TABLE TWO
Composition of the SC
Ingredients Percentage (w/w)
Long chain ceramides 37
Cholesterol 20
Fatty acids (as linoleic acid) 9
Water 25
Cholesterol sulfate and esters 8
Others 1
Amino acids
Lactic acid
Urea
Citrates
Sugars
Metallic salts
Sodium, calcium, iron,
zinc, copper, et al.
October 2018 Spray 39