INTRODUCTION
Melanin provides pigmentation to skin, hair, and eyes and protects epidermal cells by absorbing harmful ultraviolet (UV) rays. Hyperpigmentation results from excess, cumulative melanin triggered by extrinsic aggressors such as UV radiation and pollution, and intrinsic factors including genetics, hormonal fluctuations, and imbalances that induce oxidative stress.1-3
Melanogenesis is a complex biochemical process that involves multiple pathways.4 Among the primary cell signaling pathways that influence skin pigmentation are melanocyte activation, melanosome formation, melanin synthesis, and melanin transfer and removal.4 Melanocyte activation and formation can be triggered by UV exposure, pregnancy, other hormonal fluctuations, inflammation, and aging. Sun exposure causes the body to increase production of melanin to defend against UV rays, increasing skin pigmentation. UV radiation produces free radicals, which, along with UV light, activate biological mechanisms that impact melanocytes.5 In the presence of tyrosinase, a key enzymatic regulator of melanin production,6 the amino acid L-tyrosine is converted to dopaquinone (DOPA), which is then transformed into either eumelanin (black-brown pigmented melanin) or pheomelanin (yellow-red pigmented melanin).4,5 Multiple modalities or agents are often required to manage hyperpigmentation sufficiently, and strategies always include routine, daily use of sunscreen and sun-protective measures. In an effort to address the multiple pathways involved in the development of melanin, recommended regimens often include the adjunctive use of several topical prescription and/or nonprescription products, including hydroquinone (HQ), retinoids, alpha-hydroxy acids (AHAs), and antioxidants.7-13
Melanogenesis is a complex biochemical process that involves multiple pathways.4 Among the primary cell signaling pathways that influence skin pigmentation are melanocyte activation, melanosome formation, melanin synthesis, and melanin transfer and removal.4 Melanocyte activation and formation can be triggered by UV exposure, pregnancy, other hormonal fluctuations, inflammation, and aging. Sun exposure causes the body to increase production of melanin to defend against UV rays, increasing skin pigmentation. UV radiation produces free radicals, which, along with UV light, activate biological mechanisms that impact melanocytes.5 In the presence of tyrosinase, a key enzymatic regulator of melanin production,6 the amino acid L-tyrosine is converted to dopaquinone (DOPA), which is then transformed into either eumelanin (black-brown pigmented melanin) or pheomelanin (yellow-red pigmented melanin).4,5 Multiple modalities or agents are often required to manage hyperpigmentation sufficiently, and strategies always include routine, daily use of sunscreen and sun-protective measures. In an effort to address the multiple pathways involved in the development of melanin, recommended regimens often include the adjunctive use of several topical prescription and/or nonprescription products, including hydroquinone (HQ), retinoids, alpha-hydroxy acids (AHAs), and antioxidants.7-13
