Histopathological, morphometric, and stereologic studies of dermocosmetic skin formulations containing vitamin A and/or glycolic acid

Abstract

Among the many active agents for dermocosmeric purposes that have been described, marketed, and prescribed, vitamins (vitamin A palmitate among them) and alpha-hydroxy acids such as glycolic acid have been gaining scientific importance. Vitamin A palmitate contributes to the maintenance of skin softhess and smoothness, improving the water barner properties of the tissue. Glycolic acid has yielded highly satisfaccory results in terms of recovery of aged skin. The combination of low concentrations of glycolic acid with vitamin A palmirate has been extensively used in dermocosmetic formulations. The objective of the present study was to investigate the histopathological alterations caused by formulations containing vitamin A and/or glycolic acid in guinea pig skin, determined by appropriate stereologic techniques. The following formalations were applied to specific shaved areas of guinea pig skin: gel alone (used as the dermocosmetic base), gel with vitamin A added, gel with glycolic acid added, and gel with both vitamin A and glycolic acid added. After application of the formulations for one week, skin biopsics were obtained from the animals and we investigared the histopathological alterations. Under the pressent experimental conditions, both the formulations containing vitamin A and glycolic acid caused increased epidermal thickness, with cells of larger volume due to intra- and extracellular edema (hydration) This epithelial thickening was nor limited to the upper cell layers but was also present in the basal and spinous layers. These alterations were even more evident with the use of the formulation containing a combination of vitamin A and glycolic acid.