Penetration Enhancers Assessed by Corneoxenometry

Abstract

Chemical enhancers abating the barrier function of the stratum corneum act in a number of ways. Their relative effects in mixtures are notoriously difficult to determine. Corneoxenometry is a bioassay where xenobiotic interactions with corneocytes are assessed using reflectance colorimetry. It was used to evaluate comparatively the effects of ethanol and laurocapram at various dilutions. In addition, a 10% propylene-glycol-based gel supplemented with N-acetyl-L-cysteine, urea and salicylic acid in various concentrations was tested. The relative index or irritancy (RII) was calculated for each formulation. RII is a surrogate marker of lipid removal and disorganization, and of protein denaturation in the stratum corneum. It is likely a good predictor for barrier function alterations and represents a cheap and rapid alternative to animal testing.

Skin Weathering: The Face at the Interface

“…However, interpreting the data in terms of 'mature' and 'immature' corneocytes could be challenged. Indeed, the pattern of variations in staining closely resembles the variegation previously reported in the corneosurfametry and corneoxenometry bioassays [6,25,26] and squamometry as well [27,28]. All these methods basically rely on the relative access of dyes to particular binding sites on corneocytes after damaging them.…”

Overcoming the Stratum Corneum: The Modulation of Skin Penetration

“…They found that the use of the binary solvent system, ethanol and water in the ratio of 70: 30 v/v, is an effective vehicle for the development of a transdermal therapeutic system for nicardipine hydrochloride. A linear relationship between ethanol concentration and a surrogate marker of lipid removal and disorganization in the stra- tum corneum has been found by means of corneoxenometry, a bioassay where interactions between xenobiotics and corneocytes are assessed using refl ectance colorimetry [26] . The more lipophilic monoethylether of the bivalent alcohol diethylene glycol (Transcutol ® ) has been a frequently used skin penetration enhancer in recent years.…”

Skin compatibility of cyclodextrins and their derivatives: a comparative assessment using a corneoxenometry bioassay

“…Any disruption in the lipid bilayers of the SC and any protein denaturation of the corneocytes, a process that may reduce the barrier function of the SC and may induce irritation, is revealed by controlled colorimetric means. The effect of organic solvents, penetration enhancers and barrier creams were tested by corneoxenometry with relevant predictive value [4,6,7]. In this study, the corneoxenometry suggested that all tested CD are globally well tolerated by the skin because CIM medians values were above the threshold value of 30 for skin mildness (Fig.…”