Efficacy of a Comprehensive Serum in Japanese Subjects With Moderate to Severe Facial Hyperpigmentation
January 2017 | Volume 16 | Issue 1 | Original Article | 36 | Copyright © 2017
Elizabeth T. Makino BS CCRA MBA,a Shoichiro Yano MD,b Tsing Cheng PhD,a Rahul C. Mehta PhDa
aSkinMedica, Inc., an Allergan Company, Irvine, CA bThomas J. Stephens & Associates, Inc.,Tokyo, Japan
OBJECTIVE: Due to innate differences in the biochemical processes of melanogenesis between people of different ethnic origins, the clinical efficacy and tolerability of a novel comprehensive hydroquinone-free and retinol-free serum for pigmentation control was assessed in Japanese subjects. METHODS: A double-blind, placebo-regimen controlled clinical study was conducted to assess the efficacy and tolerability of a novel comprehensive hydroquinone-free and retinol-free serum (LYT2) in Japanese subjects presenting with moderate to severe facial hyper- pigmentation. Subjects were randomized to receive LYT2 plus a sunscreen placebo regimen or only the sunscreen placebo regimen. Clinical assessments for overall hyperpigmentation and skin tone evenness by the blinded investigator and standardized digital photography were conducted at all visits (baseline and weeks 4, 8, and 12). RESULTS: Thirty-five female and male subjects aged 37-67 years completed the twelve-week study. Subjects treated with LYT2 showed early signi cant reductions in both mean overall hyperpigmentation and skin tone evenness scores at week 4, with continuing significant reductions through week 12. LYT2 showed significantly greater improvements in skin tone evenness scores compared to the sunscreen placebo regimen at weeks 4 and 12. Standardized digital photographs support the overall improvements observed by the investigator. Both treatments were well-tolerated with mean tolerability scores remaining mild or below throughout the study duration. DISCUSSION: LYT2 combines multiple ingredients that modulate several key biochemical pathways in melanogenesis to work on multiple types of pigmentary conditions in people of various ethnic origins. In a previous multi-ethnic study, LYT2 showed clinical efficacy in African American, Hispanic, and Caucasian sub-groups. The present study supports the efficacy and tolerability of LYT2 in improving the appearance of facial hyperpigmentation in Japanese subjects. J Drugs Dermatol. 2017;16(1):36-40.
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Ethnic skin (or skin of color) refers to non-Caucasian skin encompassing all races and ethnicities other than non-Hispanic white. People with ethnic skin can be classified into several ethno-racial groups such as African American, Hispanic, East Asian, Indian, Middle Eastern etc. While general structure and function of the skin is similar between ethno-racial groups, physiologic differences do exist, of which skin pigmentation is the most discernable. Since the number of pigment-producing melanocytes is not significantly different among racial groups, variations in the melanogenesis process are the determining factors in skin color.1,2 Melanogenesis involves a number of complex molecular pathways that include melanocyte activation, melanosome development, melanin synthesis and melanosome transfer.3 Melanocytes from darker skin types have more tyrosinase activity, which results in greater melanin content.4,5 Furthermore, melanosomes in African skin are larger in size than those in Caucasian skin, with Asian skin having melanosomes of intermediate size. Additionally, the distribution pattern of melanosomes within keratinocytes is a determining factor of skin color. In darker skin types the melanosomes are predominantly distributed individually throughout the cytosol, whereas lighter skin types show small clusters of melanosomes.6-8 A combination of individual and clustered melanosomes can be found in Asian skin.9 These differences may influence melanosome degradation within the keratinocyte. In dark skin types melanosomes are present in all epidermal cell layers up to the stratum corneum, whereas in light skin the melanosomes are mostly confined to the basal layers of the epidermis. Light skin keratinocytes appear to lose melanosomes more rapidly during terminal differentiation, as the smaller, clustered melanosomes are degraded more efficiently resulting in an absence of melanosomes in the upper epidermal cell layers of Caucasian skin.10-12 Studies have shown that skin aging manifests differently between races and ethnicities due to biological differences.13,14 Pigmentary changes are generally the first visible signs of skin aging in Asian populations rather than wrinkling. Wrinkles are not readily apparent until after the age of 50 years in Asian skin, and even then to a lesser extent compared to Caucasian