Objectives N-undecyl-10-enoyl-l-phenylalanine (Sepiwhite®, N-undecylenoyl phenylalanine), a reported alpha-melanocyte-stimulating hormone (MSH) receptor antagonist, has been observed to reduce melanin production in cultured melanocytes. In other testing, niacinamide has been found to inhibit melanosome transfer in cultured cells and to reduce the appearance of hyperpigmented spots in clinical studies. Since these two agents function by different mechanisms, we conducted two studies to determine if their combination is more effective than niacinamide alone in reducing facial hyperpigmentation.
Methods Two double-blind, 10-week (2-week washout + 8-week treatment), left-right randomized, split-face clinical studies were conducted. In one, two groups of Japanese women applied one of two pairs of test emulsion formulations: a vehicle control and a 5% niacinamide formulation (n= 40), or a 5% niacinamide and a 5% niacinamide plus 1%N-undecylenoyl phenylalanine formulation (n = 40). Each formulation was applied to the randomly assigned side of the face. In the second study, Caucasian women applied one of three emulsions: vehicle control, 5% niacinamide formulation, or combination 5% niacinamide plus 1%N-undecylenoyl-phenylalanine formulation to the randomly assigned side of the face (n = ∼60 treatment sites per formulation). In both studies, hyperpigmented spots were evaluated at weeks 4 and 8 by quantitative image analysis.
Results In both studies, the combination formulation was significantly more effective than the vehicle and the 5% niacinamide formulation in reducing the appearance of hyperpigmentation after 8 weeks.
Conclusions The combination of 5% niacinamide and 1%N-undecylenoyl phenylalanine is an effective anti-aging technology for use on facial skin.