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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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Having a solid understanding of melanogenesis—the process by which pigment is produced and deposited—is critical to effective ingredient selection and successful treatment. Melanogenesis is a chain of multiple chemical events within the skin that begins with an inflammatory or hormonal stimulus that instigates the release of melanocyte-stimulating hormones (MSH). Then, within the melanocyte, the enzyme tyrosinase is released from the rough endoplasmic reticulum (RER) and acts on the amino acid tyrosine to convert it to L-DOPA. Next, tyrosinase binds with copper and acts on the L-DOPA, converting it into dopaquinone, resulting in the formation of melanosomes, or “packets” of pigment. These melanosomes are transported along the dendrites (arms) of the melanocyte and transferred into the keratinocyte, creating an umbrellalike pattern to protect the DNA within the cell, resulting in hyperpigmentation.
To effectively prevent and correct hyperpigmentation, it is best to use a variety of topical ingredients that address different points within this chain.
Azelaic acid. This is found naturally in castor beans and many grain products. It is also effective in treating hyperpigmentation, because it inhibits the growth of melanocytes and exerts cytotoxic action on melanocytes without negatively affecting the surrounding healthy cells. It also suppresses the production of the enzyme tyrosinase and is a mild exfoliant, which helps to normalize keratinization in the skin. This antibacterial ingredient is available in higher prescription strengths for rosacea and acne treatment medications.
Glycyrrhiza glabra (licorice root extract). This is used in many product formulations with the capability to suppress the tyrosinase activity of melanocytes without cytotoxicity, making it another highly safe and effective skin-brightening ingredient. Licorice root extract also is effective in treating breakout-prone skin, because it suppresses 5-alpha reductase, the enzyme responsible for increased sebum production. Licorice also has demonstrated effective anti-inflammatory properties.
Hydroquinone. This is the only U.S. Food and Drug Administration (FDA)-approved skin-lightener, and is considered safe and effective. It works by destroying malfunctioning melanocytes without harming normally functioning cells. There has been continuing controversy surrounding the topical use of this ingredient, primarily due to incomplete or incorrect information suggesting that hydroquinone causes cancer. Contrary to the belief of some, hydroquinone is not banned in Europe, Canada or other countries; it is simply more tightly regulated and typically available only by prescription. In the United States, however, products formulated with 2% hydroquinone or less are still available as over-the-counter (OTC) drugs, while percentages from 4% and above require a prescription.