Comedolytic effect of a novel RARgamma-specific retinoid, ER36009: comparison with retinoic acid in the rhino mouse model.

In addition to natural retinoids, new synthetic retinoids, such as adapalene and tazarotene, are currently available for the treatment of acne. In this study, we evaluated the comedolytic effect of a novel retinoic acid receptor (RAR)-gamma specific retinoid, ER36009, in the rhino mouse. The animals were treated for five days a week with ER36009 (0.00001, 0.000025, 0.00010, 0.00025%), all-trans-retinoic acid (RA) (0.001, 0.005, 0.010, 0.050%), two commercial formulations (Differine((R)) 0.1% adapalene gel, and Tazorac 0.1% tazarotene gel) and acetone as a control, for two weeks. After the treatments, utricle diameter and apoptosis of the follicular epidermis were examined. ER36009 was 96 times more potent than RA in the utricle diameter reduction assay. It also eliminated apoptosis of the follicular epidermis and restored normal apoptosis at the granular layer. These data indicate that ER36009 is a potent comedolytic agent compared with other currently available retinoids.