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By: Gül Ç. Zone
Posted: January 31, 2014, from the February 2014 issue of Skin Inc. magazine.
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It is important to remember that stronger is not always better when it comes to peels, as evidenced in the treatment of hyperpigmentation, which can be a challenge to many skin care professionals. Trichloracetic acid (TCA) peels can effectively lift off and remove pigmented skin cells that have progressed through the skin’s natural maturation cycle; however, they can be counterproductive when working with higher Fitzpatrick skin colors or in types where melanocytes are easily triggered due to inflammatory responses in the skin by these aggressive peeling agents. Another approach may be to perform lighter, less aggressive peels that progress over a period of time to achieve better long-term results.
For the esthetic practice, there are a wide range of acid and nonacid ingredients available, and many have secondary benefits, such as antibacterial or skin-lightening properties. Esthetic peels are less aggressive than medical peels and act only superficially on the upper epidermis, but they provide the esthetician with more control of treatment results. Esthetic peels include mild enzyme peels, which affect only the upper stratum of the epidermis; acid peels, which target the epidermis from the outer surface inward; and nonacids, such as retinol or retinoic acid (vitamin A derivatives), which target the lower layers of the epidermis to kick start the basal stem cells, and initiate new cell replication that forces cells to the outer surface, thus affecting a natural peel.
The main families of chemical peel systems include the ubiquitous alpha hydroxy acids (AHAs), including glycolic and lactic acid; carboxylic and dicarboxylic acids; beta hydroxy acids (BHAs); and blends with other acids and ingredients. See Common Active Peel Ingredients.
Azelaic peels, based on azelaic acid, a dicarboxylic acid, represent one of several peel acids with multiple benefits. It promotes a mild peel of the upper layer of the epidermis, and it can also offset post-inflammatory hyperpigmentation (PIH), a problem that can plague a peel process, particularly in pigmented skin. Azelaic acid is able to inhibit a key enzyme needed in the skin’s pigmentation process—tyrosinase—slowing excess pigmentation by reducing melanin production. Another mild acid, kojic acid, is also used in skin care products to affect mild peeling while exhibiting strong tyrosinase-inhibition and anti-inflammatory properties.
In addition to preventing hyperpigmentation, some of the acid systems are effective as anti-acne treatments. The antibacterial properties of azelaic acid, particularly at lower pHs, are very effective against skin bacteria often associated with acne, such as propionibacterium. The peeling effect of the acid helps remove the initial sebum/epidermal plug that precedes the acne comedone, but also is effective at suppressing bacteria growth at the site. Salicyclic acid, a BHA with unique oil solubility that common AHAs do not have, is also an effective acne treatment. Mandelic acid, an aromatic keto-acid, has been shown to have both antibacterial and bacteriostatic properties.