Analytic quantification of solar lentigines lightening by a 2% hydroquinone-cyclodextrin formulation

Abstract

Background: The innate melanin pigmentation of skin is modulated during lifetime by a series of factors, including ageing and chronic ultraviolet light exposure. Actinic lentigines may be of particular concern from a cosmetic point of view. Conventional hypopigmenting agents are usually deceptive. Using cyclodextrins to form inclusion compounds with these agents might represent a more active drug delivery system.

Objective: To assess sensitive and objective methods predicting the effects of a 2% hydroquinone-cyclodextrin formulation on solar lentigines.

Study design: Thirty Asian adults applied a 2% hydroquinone-cyclodextrin formulation once daily on solar lentigines of a forearm for 2 months. The other untreated forearm served as a control. Monthly assessments were performed using skin colorimetry and fluorescence video recording combined with image analysis. Corneomelametry following photodensitometry of cyanoacrylate skin surface strippings was performed after melanin staining of the samples.

Results: The control untreated solar lentigines showed no significant variations in the biometrological parameters. By contrast, the test formulation induced lightening of the solar lentigines. Corneomelametry disclosed improvement after 1 months' treatment, whereas the other assessments only reached significance after 2 months.

Conclusions: A 2% hydroquinone-cyclodextrin formulation proved to be effective in lightening actinic lentigines. Corneomelametry predicted the effects discernible at a later stage by in vivo colour assessments of the melanin content.