The influence of lecithin and urea on the in vitro permeation of hydrocortisone acetate through skin from hairless mouse

Many workers have attempted to modify the permeability characteristics of skin. In the present work, the in vitro permeation of a model lipophilic drug (hydrocortisone acetate) was studied through hairless mouse skin. The drug was applied in poloxamer 407 gels containing known concentrations of lecithin or urea as penetration enhancers. The results of permeation studies showed that the flux and the retention of the drug were dependent on the concentration of the penetration enhancers. Lecithin (8.0% w/v) caused a retention of seven times more than that of urea (12.0% w/v). The mechanism of penetration enhancement was investigated by differential scanning calorimetry (DSC) and FTIR spectroscopy of the stratum corneum (SC) from hairless mouse treated with solution Of lecithin and urea. The lecithin was found to have a significant influence on the lipid matrix of the SC, suggesting a disruption of the intercellular lipid lamellar structure. (C) 1997 Elsevier Science B.V.