Effect of 1,4-cyclohexanediol on percutaneous absorption and penetration of azelaic acid

The objective of this study is to investigate the effect of 1,4-cyclohexanediol as a retardant on the percutaneous absorption and penetration of azelaic acid. Hairless rat skin was mounted on Franz diffusion cells and treated with topical formulations containing solubilized azelaic acid with and without 1,4-cyclohexanediol. The skin was separated into stratum corneum and the deeper skin layers. The azelaic acid collected in receptor medium and each layer at the end of each time point was extracted and quantified. A significant decrease in flux across the skin suggests a penetration retardation effect of 1,4-cyclohexanediol (42.50 μg/cm2/h in the presence of vs. 76.25 μg/cm2/h in the absence of) at active loading level of 1.13 mg/cm2. The penetration retardation effect was also observed at higher active loading level (2.82 mg/cm2). Furthermore, presence of 1,4-cyclohexanediol in the topical formulation did not reduce the skin and epidermal retention of azelaic acid, suggesting its potential use in the development of superior topical formation for reducing potential systematic side effect while maintaining therapeutic efficiency.