BACKGROUND: Topical niacinamide and N-acetyl glucosamine (NAG) each individually inhibit epidermal pigmentation in cell culture. In small clinical studies, niacinamide-containing and NAG-containing formulations reduced the appearance of hyperpigmentation. OBJECTIVES: To assess the effect of a combination of niacinamide and NAG in a topical moisturizing formulation on irregular facial pigmentation, including specific detection of changes in colour features associated with melanin. METHODS: This was a 10-week, double-blind, vehicle-controlled, full-face, parallel-group clinical study conducted in women aged 40-60 years. After a 2-week washout period, subjects used a daily regimen of either a morning sun protection factor (SPF) 15 sunscreen moisturizing lotion and evening moisturizing cream each containing 4% niacinamide + 2% NAG (test formulation; n = 101) or the SPF 15 lotion and cream vehicles (vehicle control; n = 101). Product-induced changes in apparent pigmentation were assessed by capturing digital photographic images of the women after 0, 4, 6 and 8 weeks of product use and evaluating the images by algorithm-based computer image analysis for coloured spot area fraction, by expert visual grading, and by chromophore-specific image analysis based on noncontact SIAscopy for melanin spot area fraction and melanin chromophore evenness. RESULTS: By all four measures, the niacinamide + NAG formulation regimen was significantly (P < 0.05) more effective than the vehicle control formulation regimen in reducing the detectable area of facial spots and the appearance of pigmentation. CONCLUSIONS: A formulation containing the combination of niacinamide + NAG reduced the appearance of irregular pigmentation including hypermelaninization, providing an effect beyond that achieved with SPF 15 sunscreen.
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Kimball et al. (2009) studied this question.
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