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

Purpose, 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. Methods. 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. Results. The dermal application of therapeutically used acids, such as sali cylic acid and azelaic acid, caused a plain change of microacidity (pH) ins ide the skin. Species-linked differences between rat and human skin samples with respect to penetration and microacidity were found. Conclusions. ESRI has been shown to be a new and completely noninvasive met hod to monitor microacidity in different skin layers and on the skin surfac e. This nondestructive method allows serial measurements on skin samples to be performed without any preparatory steps.