A Double Blind, Randomized Clinical Trial of 4% Niacinamide Versus 0.05% Desonide for the Treatment of Axillar Hyperpigmentation

Axillary hyperpigmentation is frequent in dark skin population, is possible a type of postinflammatory hyperpigmentation present in phototypes IV to VI. Previous reports have described increased intensity of Masson-Fontana, anti-tyrosinase and/or anti-TRP1 staining, indicative of melanocyte stimulation and increased melanin production, but the exact mechanism is unknown. The hair plucking, the rubbing of clothes on skin and physical stimulation from washing and drying the underarm are factors implicated. The objective of our study is evaluate the depigmenting effect of topical niacinamide versus desonide in axillary hyperpigmentation through the histochemistry and immunohistochemistry staining.

The study population will include at least 30 axillas with hyperpigmentation in a population with phototype III-V and aged 18-50 years old. Informed consent will be obtained from the patients, under approval by the local ethical committee (Institutional Review Board). The patients are going to be randomly assigned to receive 4% niacinamide, 0.05% desonide or placebo daily once at night. None hygienic habit is going to be modified. Volunteers will be evaluated at baseline and 9 weeks later, with histochemical and immunohistochemical analysis (biopsies), colorimetric value axis L*, a*, b* (Chromameter CR-300, Minolta, Osaka, Japan), Transepidermal Water Loss (TEWL) by means of an evaporimeter (Dermalab, Cortex Technology, Denmark), clinical assessment and photography control.

Statistical analysis was performed using t student, the level of significance was set at 5%. And clinical evaluation will be analysed by means of chi square test.