The influence of Span®20 on stratum corneum lipids in Langmuir monolayers: comparison with Azone®

Recently we have proved that Span 20 has the same enhancer effect as Azone on in vitro percutaneous penetration of lipophilic compounds (logP(oct) from 1.34 to 2.33). The purpose of this work is to study the interactions of Span 20 with stratum corneum lipids monolayers and to compare them with Azone. The surface pressure-area characteristics of Span 20 in mixed monolayers with different model lipids (ceramides, cholesterol, free fatty acids and two mixtures of ceramides+cholesterol, and ceramides+cholesterol+free fatty acids) in similar proportions to that which exists in human stratum corneum lipids were recorded as compression isotherms at 25 degrees C. Azone was also investigated on mon…