Characterize by light
to moderate penetration, and minimal or no discomfort. These peels/exfoliators
are excellent at improving the texture of the skin and evening out the skin
tone. For maximum results, they can and should be alternated.
Alpha
Hydroxy Acids:
While Glycolic and Lactic
acid peeling agents have equivalent results, the following shows that lactic
acid peels have many benefits over glycolic acid peels. Glycolic Acid is the
most commonly used AHA. Because of its small molecular weight and size, it
is presumed to have a better capacity to penetrate skin. Lactic acid on the
other hand, has a larger molecular weight than glycolic acid but is capable
of being converted into pyruvic acid (an alpha keto acid) which is presumed
to be a more effective exfoliating agent.
Lactic Acid:
- Lactic Acid is a normal
metabolite for mammals. It has no toxicity.
- With its longer reaction
time, lactic acid is safer than glycolic acid.
- There is a better control
of the peel without burning.
- Lactic acid enhances
the absorption of other substances and is a superb humectant -- it attracts
water molecules already present in your skin to the surface, making it an
effective moisturizer.
- There is a minimal
chance of adverse effects.
Glycolic Acid
- Glycolic Acid is of
vegetable origin (non-mammalian).
- There is a rapid reaction
time.
- There is less control
of peel irritation.
- In working with the
higher clinical strengths 70%, there have been many reported incidents of
adverse effects, like discoloration and scarring.
GLYCOLIC ACID is
an alpha hydroxy acid derived from sugar cane. It is nontoxic and well tolerated
by most people. Glycolic acid peels are usually very superficial peels. However,
they need to be neutralized to terminate their action, otherwise, they may
penetrate too deep and "overpeel" the skin. Glycolic acid peels exfoliate
dead layers of the skin and, typically, require no downtime. They also help
reduce acne related conditions by freeing impacted debris from the pores,
improve texture of the skin. Because
of the small size of its molecules, which facilitates penetration, results
can be faster for people who do not have sensitive skin.
LACTIC ACID PEEL
Lactic acid is an alpha hydroxy acid derived from sour milk. It is ideal for
sensitive skin or skin unable to tolerate glycolic acid. Lactic acid peel
helps to eliminate germs, toxins and dead cells. It also helps to maintain
the skin's pH factor. Lactic Acid Peel is indicated for the rejuvenation of
sun-damaged skin, acne, unwanted pigmentation, fine lines, and actinic damage.
It actually increases new cell growth, stimulates collagen production, and
new elastic fibers in the deeper dermal layers. Lactic Acid not only is a
superior exfoliant, but may be one of the best treatments yet for hyper-pigmentation.
Lactic's water binding capacity
exceeds that of glycerol, sorbitol, other AHAs, salicylic acid, and propylene
glycol yet functions like other AHA, providing additonal benefits. [1] [2] Lactic
acid can produce a measurable increase in skin thickness (+43% at week 11 with
21.6% solution). Other findings have correlated well with lactic acid’s ability
to reverse symptoms of skin aging. [3] [4]
How
important is the percent and pH?
Beta
Hydroxy Acid
SALICYLIC ACID
or beta hydroxy acid is derived from aspirin. This treatment is particularly
helpful in clearing clogged follicles and in promoting exfoliation. Salicylic
acid is lipid (oil) soluble solution and is antibacterial, thus giving acne
sufferers added relief. In fact, Salicylic acid is considered one of the best
peels for relieving acne. This peel is a more dramatic method in obtaining
a healthy, bright, clear skin appearance. Salicylic acid works differently
than Glycolic or Lactic acids. Salicylic acid works from the deeper layers
of the skin and able to penetrate the comedones (blackheads) better than other
acids.
A
closer look at the pH and Percents of AHA's
How important is the pH
of an acid? The concentration of “free” acid is what determines activity
(table); Product pH is a critical aspect of efficacy with acids. Although higher
concentrations of AHA should be more potent, pH is more important as the following
tables illustrates.
The efficacy of alpha hydroxy
acids depends less on the specific AHA that is being used, but rather on the
concentration of the AHA and the pH of the medium in which it is used. For skin
renewal, a lower (more acidic) pH and higher concentration of acid are more
effective. Lactic acid both pH and concentration are critical. At a fixed lactic
acid concentration (lactic acid 10%), the desquamative (exfoliation) effect
was highly pH dependent. At a fixed pH (lactic acid percentage 5%, 10%, 15%
at fixed pH of 3.0), the turnover rate of skin was concentration dependent.
The desquamative and proliferation-stimulating effects of lactic acid are very
pH and concentration dependent.[5]
In determining what you
want to accomplish, the free acid value of the AHA is responsible for
cell renewal stimulation. A 4% free acid is usually the threshold minimum
for this effect.
| Free
Acid Value |
Effect |
| 0% - 2% |
Increased
moisturization |
| 2% - 4% |
Smoother,
softer skin. Moderate increase in glycosaminoglycans (GAGs). |
| 4% - 8% |
Moderate
increase in squamous cell turnover. Significant increase in GAGs. |
| 8% - 12% |
Significant
increase in squamous cell turnover. Moderate increase in collagen deposition |
| 12% - 15% |
Significant
increase in collagen deposition. Thicker, less fragmented elastic fibers
|
| 20% |
Reversal
in basal cell atypia. More uniform melanin pattern |
The following table demonstrates
how the pH effects the Free Acid Values of AHA's. It will help you determine
the Free Acid Value of an AHA that you might elect to work with, or have worked
with in the past along, and how Free Acid Values relate to accomplishing skincare
goals.
| Percent
of Glycolic on Label |
pH |
Free
Acid Value |
| 7% |
1.8 |
6.9% |
| 8% |
3.67 |
4.7% |
| 12% |
3.3 |
8.5% |
| 15% |
3.77 |
8% |
| 20% |
4.3 |
4.8% |
| 20% |
3.4 |
14.6% |
| 20% |
2.55 |
18.6 |
| 50% |
1.3 |
50% |
As demonstrated in the above
tables, working with a 20% AHA at 4.3 pH will have less effect on squamous cell
turnover and less collagen deposition than working with a 7% solution at 1.8
pH.
If you are not well versed
in working with acids, application of 15% AHA or higher should be performed
by a professional.
- Never assume all acids
are equal and ALWAYS patch test any new acid to determine any sensitivities
prior to treating the area.
- Never assume, having
used other acids previously, that your skin can readily handle the acid and
you can allow the same time on the skin with a new acid product.
- Never use an acid when
you cannot completely pay attention to what you are doing.
- Always follow directions
The FDA and dermatologists
advise consumers who use AHA products to follow these precautions:
- Always use a sunscreen
of at least SPF 15.
- Wide-brimmed hats and
shade-seeking behavior are also advised.
- Buy products with adequate
labeling including a list of ingredients, the name and address of the manufacturer,
the product's AHA concentration, and the product’s pH. The first two are mandatory;
the third is optional.
- If you are a first-time
user of the product, do a patch test.
- Stop using the product
if you experience an adverse reaction. If you have a reaction, see a dermatologist.
- Berardesca E, Distante
F, Vignoli GP, Oresajo C, Green B. Alpha hydroxy acids modulate stratum corneum
barrier function. Br. J. Dermatol 1997;137:934-8.
- Green B, Tseng C, Wildnauer
R, Herndon J, Rizer, R. Safety and Efficacy of a Gluconolactone (Poly Hydroxyacid)
Containing Regimen on Sensitive Skin and Photodamage Following Controlled
Consumer Use. Amer Acad of Derm Poster Exhibit: New Orleans, March, 1999.
- Ditre CM, Griffin TD,
Murphy GF, Sueki H, Telegan B, Johnson WC, Yu RJ, Van Scott EJ. Effects of
a-hydroxy acids on photoaged skin: A pilot clinical, histologic, and ultrastructural
study. J Am Acad Dermatol 1996:34:187-95.
- Bernstein EF, Underhill
CB, Lakkakorpi J, Ditre CM, Uitto J, Yu RJ, Van Scott EJ. Citric Acid increases
viable epidermal thickness & glycosaminoglycan content of sun-damaged skin.
Dermatol Surg 1997; 23: 689-94.
- Thueson DO, Chan EK,
Oechsli LM, Hahn GS, The roles of pH and concentration in lactic acid-induced
stimulation of epidermal turnover, Dermatol Surg 1998 Jun;24(6):641-5
