Salicyl esters such as methyl salicylate (oil of wintergreen) are commonly prescribed as constituents of ointments, liniments and local applications, on the assumption that they possess a greater skin penetration, owing to their lipoid solubility, than do other salicylates. The amount of salicyl absorbed under these conditions would appear nevertheless to be too small for definite systemic effects. More important than the systemic actions from local applications of such products is the information they may yield regarding dermal function. The effects on the skin as determined by the properties of the constituents and of the vehicles of the mixtures merit attention.
As a group of relatively simple chemical substances, the salicyl compounds offer a good opportunity for testing the comparative importance of lipoid and water solubility, and of the chemical reaction (basicity and acidity) in dermal absorption. Lipoid solubility has generally claimed a larger share of importance for dermal penetration