Rules that get under your skin

Chemical permeation enhancers (CPEs) are used to help medicines and cosmetics cross the skin barrier but the most efficient chemical permeation enhancers being typically also the most irritant. In the case of fluidizing chemical permeation enhancers, no correlation was found between irritation and efficiency. Using this knowledge, scientists modified ten known chemical permeation enhancers and found a significant number of fluidizers that were better than the original ones.