Non-ionic surfactant effects on hairless mouse skin permeability characteristics.

The influence of a range of polyethoxylated non-ionic surfactants upon the transport of methyl nicotinate across hairless mouse skin in-vitro was investigated using standard two-compartment diffusion cells. Those surfactants having a linear alkyl chain greater than C8 and an ethylene oxide chain length of less than E14 caused significant increases in the flux of methyl nicotinate. Surfactants having branched or aromatic moieties in the hydrophobic portion were ineffective. Maximum enhancement of flux was obtained using polyoxyethylene (10) lauryl ether (Brij 36T). Two possible modes of surfactant action are proposed. Initially the surfactant may penetrate into the intercellular regions of the stratum corneum, increase fluidity and eventually solubilise and extract lipid components. Secondly, penetration of the surfactant into the intracellular matrix followed by interaction and binding with the keratin filaments may result in a disruption of order within the corneocyte. The structural specificity required for the latter mechanism may explain, to some extent, the maximum activity obtained with the C12 surfactant.