Reduction in the appearance of facial hyperpigmentation after use of moisturizers with a combination of topical niacinamide and N-acetyl glucosamine: results of a randomized, double-blind, vehicle-controlled trial

Summary 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