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Are Your Clients in the Dark About Brightening?
By: Jennifer Linder, MD
Posted: January 31, 2013, from the February 2013 issue of Skin Inc. magazine.
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When used as directed, these OTC percentages have not been associated with any negative health effects. It is important to acknowledge that most people ingest hydroquinone every day by consuming coffee, tea, wheat and berries without ill effects. There have been multiple studies performed with hydroquinone, and the carcinogenic effects that are cited, on the Internet and elsewhere are based on tests involving high doses of pure hydroquinone fed to or injected into mice and rats. Clearly, this is not the intended use of this ingredient. The outcomes of these types of studies cannot be correlated with the topical use of lower percentages of hydroquinone. The dermatology community strongly believes that the FDA’s final decision and its studies will ultimately confirm the safety of hydroquinone.
Kojic acid. This is produced by several types of fungi and was first discovered in Japan in approximately 1989. Kojic acid’s function as a skin brightener is due to its metal chelating properties. During the melanogenesis process, tyrosinase binds with copper to catalyze the production of melanin. Kojic acid is able to chelate this copper away from tyrosinase, rendering this point of the pigment pathway ineffectual. Kojic acid also can decrease the number of melanocytic dendrites on a melanocyte—melanin-producing cells, and the quantity of melanosomes released. The ancillary antibacterial properties of kojic acid make it an effective ingredient in the treatment of breakouts, as well as the resultant PIH.
L-ascorbic acid (vitamin C). This is a unique and highly beneficial ingredient in treating hyperpigmentation. This multifunctional ingredient is ideally used daily, preferably in the morning due to its protective benefits against UV-induced oxidative stress on the skin. L-ascorbic acid is the only bioavailable form of vitamin C, and has been proven not only to convert L-DOPA back into dopaquinone in the pigment pathway, but it also protects from UV exposure, functions as a powerful antioxidant, stimulates collagen deposition and has been shown to increase epidermal thickening. Other types of vitamin C used in topical products—such as ascorbyl palmitate and other vitamin C esters—supply antioxidant protection, but not vitamin C’s other anti-aging and pigment-inhibiting benefits. This is primarily because the skin’s slightly acidic environment is unable to break the covalent bonds to free the L-ascorbic acid from the substance to which it is bound in the ester.
Lactic acid. This is found naturally in milk and sugars, and is an alpha hydroxy acid (AHA) that has been used in topical formulations for decades. AHAs are hydrophilic and assist with exfoliation by breaking down the bonds between cells, known as desmosomes. In general, AHA and superficial chemical peels are crucial to lifting hyperpigmentation, because increasing exfoliation will lead to faster, more dramatic results. Lactic acid is particularly important to skin-brightening formulations due to its ability to inhibit the enzyme tyrosinase, making it an effective melanogenesis-inhibitor. In addition, lactic acid provides antibacterial and hydrating properties.
Retinoids. These represent all members of the vitamin A family, and are essential for any skin type or condition. There are many formulations available: prescription tretinoin products; gentler formulations utilizing pure retinol; and retinol complexes—blends of retinol, retinol esters and other support ingredients. Although retinoic acid is, in fact, the most bioavailable form of vitamin A, not all clients are able to tolerate its use due to its potential for irritation. In these instances, a retinol complex or a 0.5% pure retinol would be good options, depending upon the client’s sensitivity level. These forms of vitamin A are converted into retinoic acid within the skin, delivering the benefits without the irritation of a topical retinoic acid. Retinoids have been proven to suppress the melanosome transfer that takes place during melanogenesis, stimulate matrix protein production, provide antioxidant protection, increase cellular turnover and exfoliate the surface of the skin. Retinoid products should be used at night for best results, and daytime SPF use is critical to protect the skin from heightened UV sensitivity.