EFFECT OF PENETRATION ENHANCERS AND IONTOPHORESIS ON THE ULTRASTRUCTURE AND CHOLECYSTOKININ-8 PERMEABILITY THROUGH PORCINE SKIN

The present study explores the effect of chemical penetration enhancer s and iontophoresis on the in vitro permeability of cholecystokinin-8 (CCK-8) through porcine epidermis and on the ultrastructural changes i n stratum corneum as observed by transmission electron microscopy (TEM ). Enhancer [i.e., ethanol (EtOH), and 10% oleic acid in combination w ith ethanol (OA/EtOH)] pretreatment significantly increased (p < 0.01) the permeability coefficient of CCK-8 in comparison with the control (pretreated epidermis without enhancer). Iontophoresis further increas ed the permeability of CCK-8 (p < 0.01) through the enhancer-pretreate d epidermis in comparison with the control. These results showed the s ynergistic effect of iontophoresis and enhancers such as OA/EtOH that provides an additional driving force to maintain and control the targe t flux of CCK-8. The ultrastructure of stratum corneum treated with et hanol demonstrated a loss of structural components in the superficial stratum corneum cell layers. OA/EtOH transformed the highly compact ce lls of stratum corneum into a looser network of filaments, creating an increased free volume and greater intracellular surface area. Treatme nt of stratum corneum with OA/EtOH followed by iontophoresis resulted in further swelling of stratum corneum cell layers. In conclusion, OA/ EtOH in combination with iontophoresis increased the permeability of C CK-8 by loosening and swelling of stratum corneum cell layers.