EFFECT OF PENETRATION ENHANCERS AND IONTOPHORESIS ON THE FT-IR SPECTROSCOPY AND LHRH PERMEABILITY THROUGH PORCINE SKIN

The present study explores the effect of enhancer and iontophoresis on the in vitro permeability of luteinizing hormone releasing hormone (L HRH) through porcine epidermis and biophysical changes in the stratum corneum lipids by Fourier transform infrared (FT-IR) spectroscopy. Enh ancers (e.g. ethanol, 10% oleic acid in combination with ethanol and 1 0% oleic acid in combination with propylene glycol) pretreatment incre ased (P<0.05) the permeability coefficient of LHRH. Propylene glycol a lone did not increase the permeability (P>0.05) of LHRH through the ep idermis. Iontophoresis further increased the permeability of LHRH (P<0 .05) through the enhancers (ethanol, 10% oleic acid in combination wit h ethanol, propylene glycol and 10% oleic acid in combination with pro pylene glycol) pretreated epidermis in comparison to the control (with out enhancer pretreated epidermis). This shows that iontophoresis can synergize with enhancers, such as 10% oleic acid in combination with e thanol and 10% oleic acid in combination with propylene glycol, to pro vide an additional driving force to maintain and control the target fl ux of LHRH. The FT-IR spectroscopic study was performed to investigate the effect of the above enhancers and iontophoresis on the biophysica l changes in the stratum corneum lipids. Pretreatment of the stratum c orneum with 10% oleic acid in combination with ethanol, and 10% oleic acid in combination with propylene glycol followed by iontophoresis sh ifted the antisymmetric peak position with reference to the control (w ithout enhancer and iontophoresis) from 2919.3+/-0.7 to 2927.6+/-4.1, and 2919.3+/-0.7 to 2924.2+/-1.9 cm(-1), respectively. Thus, the combi nation of enhancer and iontophoresis increased the average acyl chain disorder (lipid fluidity). The synergism in enhancement of the permeab ility of LHRH through the epidermis by iontophoresis in combination wi th enhancers (10% oleic acid in combination with ethanol, and 10% olei c acid in combination with propylene glycol) may be due to greater flu idization of the stratum corneum lipids.