Sodium Cocoyl Isethionate CAS 61789-32-0 SCI

In vitro and in vivo studies show that SCI is mild and less harmful to skin barrier than surfactants such as soap and sodium dodecyl sulfate (SDS). We recently showed that SDS forms small micelles in the aqueous solution contacting the skin relative to the water pores in the stratum corneum (SC). Therefore, SDS micelles contribute to SDS skin penetration and cause skin barrier disturbance. 

In this paper, we tried to explain the documented skin mildness of SCI by examining the size of SCI micelles relative to water pores in SC. To this end, we measured mannitol skin permeability and average skin resistivity in vitro when the skin was exposed to aqueous SCI contact solution in the context of the hindered transport aqueous porous pathway model of SC. These in vitro studies show that, SCI micelles with a radius of 33.5 + / – 1 angstrom (determined using dynamic light scattering measurements) have significant steric hindrance and cannot penetrate into SC 5 angstrom through water holes with an average radius of 29 + / – 1 angstrom. 

We believe that the failure of SCI micelles to promote SCI skin penetration and associated skin barrier disturbance is the reason for the observed mild nature of SCI skin. Through use (14) In vitro quantitative skin radioactivity determination of C radiolabeled SCI and porcine full-thickness skin (p-fts), we also finally proved that the skin penetration of SCI was independent of dose. This important finding provided additional evidence that SCI micelles could not penetrate into SC through the small water holes existing in SC, so they could not cause skin barrier disturbance.