Colorimetric assessment of the effects of azelaic acid on light-induced skin pigmentation.
A 20% azelaic acid (AZA) cream is currently used as a therapeutic agent in the treatment of acne vulgaris. Therefore, this product is intended to be applied on frequently or continuously sun-exposed skin. In certain disorders of hyperpigmentation, AZA has been reported to have a depigmenting effect as well, while showing no significant activity on normal skin. It has been suggested that AZA selectively inhibits hyperactive or malignant melanocytes. Knowing that light-stimulated melanocytes are in a state of hyperactivity, it seemed worthwhile to investigate AZA activity on light-induced skin pigmentation. This study aimed to assess the activity of 20% AZA cream on light-induced skin pigmentation in 10 subjects. There were 5 test zones, all located on the middle of the back: 2 were treated with AZA cream, 2 others with the vehicle and 1 was left untreated. Each product was applied twice daily, 5 days a week, for 4 weeks on one zone, and for 5 weeks on the other. In the middle of the fourth week, the tested zones were exposed to ultraviolet B (UVB) + UVA + visible light, with a total of 3 times the minimal erythema dose distributed progressively over 3 consecutive days. Seven and 10 days after the last irradiation, the induced photopigmentation was assessed by colorimetric and visual means. Compared with its vehicle, the AZA cream had neither a depigmenting effect nor a preventive effect on the light-acquired skin pigmentation. Moreover, interrupting or continuing the AZA treatment after skin irradiation had no influence on the resulting pigmentation.
Duteil
L
L
Centre de Pharmacologie Clinique Appliquée à la Dermatologie, Nice, France.
Ortonne
J P
JP
D000328:Adult; D003124:Colorimetry; D003879:Dermatologic Agents / Q000008:administration & dosage / Q000494:pharmacology*; D003998:Dicarboxylic Acids / Q000008:administration & dosage / Q000494:pharmacology*; D005260:Female; D006801:Humans; D008297:Male; D008544:Melanocytes / Q000187:drug effects; D012880:Skin Pigmentation / Q000187:drug effects* / Q000528:radiation effects; D014466:Ultraviolet Rays
D003879:Dermatologic Agents; D003998:Dicarboxylic Acids; C010038:azelaic acid