Influence of drug treatment on the microacidity in rat and human skin--an in vitro electron spin resonance imaging study.

Abstract

The possibilities of the noninvasive examination of microacidity (5) in different depths of the skin in vitro was explored, and the impact of drug treatment on the pH inside the skin was studied. Spectral-spatial electron spin resonance imaging (ss-ESRI) and pH-sensitive nitroxides were used to obtain a pH map of rat and human skin in vitro. The dermal application of therapeutically used acids, such as salicylic acid and azelaic acid, caused a plain change of microacidity (pH) inside the skin. Species-linked differences between rat and human skin samples with respect to penetration and microacidity were found. ESRI has been shown to be a new and completely noninvasive method to monitor microacidity in different skin layers and on the skin surface. This nondestructive method allows serial measurements on skin samples to be performed without any preparatory steps.