Deuterium NMR investigation on the effect of isopropyl myristate on the skin barrier using a model stratum corneum

The function of the skin as a barrier is found to be closely associated with lipids in the stratum corneum (SC). At physiological temperature, SC lipids form solid or crystalline domains which may contribute to skin impermeability. A 2 ~ - ~ ~ study has been conducted to observe the effect of Isopropyl Myristate (IPM), a skin penetration enhancer, on the physical properties of model SC (MSC). IPM was added to MSC comprising equimolar mixtures of N-palmitoyl D-erythro-sphingosine (Cerl6), cholesterol and palmitic acid (PA), containing either Cer 16-d31 or PA-d31. 2 ~ - ~ data showed that IPM had pronounced effects on the phase behaviour of MSC. Relative proportions of solid, liquid-crystalline and isotropic phases varied with temperature and IPM concentration. Further experiments, using synthesized chain-deuterated IPM, allowed the examination of the behaviour of IPM in MSC. These data, coupled with other studies, can help elucidate the effect of IPM on the integrity of the SC barrier.