title: The effect of pretreatment with terpenes on transdermal iontophoretic delivery of arginine vasopressin.
abstract: This study investigates the effects of terpenes and iontophoresis on the in vitro permeation of arginine vasopressin (AVP) through rat skin and the biophysical changes induced by the chemical enhancers in the stratum corneum (SC) lipids by FT-IR spectroscopy. Pretreatment with terpenes (e.g. 5% w/v, carvone, pulegone, cineole and menthol in EtOH:W (2:1) system) increased (P < 0.05) the flux of AVP in comparison to control (not pretreated with enhancer) but was not significantly different (P > 0.05) in comparison to iontophoresis. Amongst different terpenes studied maximum enhancement ratio was observed with cineole. In combination, iontophoresis did not further increase (P > 0.05) the permeation of AVP through the enhancer pretreated epidermis in comparison to pretreatment with enhancer or iontophoresis alone. Hence it was concluded that although the combination was effective in flux enhancement compared to control, there was no synergism in action between terpenes and iontophoresis. FT-IR spectroscopic studies revealed that EtOH:W (2:1) system is not effective in lipid extraction. The area under the symmetric and asymmetric stretching peaks at 2850 and 2920 cm(-1) revealed that at the concentration used terpenes did not extract any lipids from the epidermis. The mode of action of terpenes is attributed to the breaking of hydrogen bonds between the ceramide head groups of lipids in the SC leading to greater fluidization of the SC lipids.
authors.affiliation: Department of Pharmaceutics, National Institute of Pharmaceutical Education and Research (NIPER), Sector-67, SAS Nagar, Punjab 160 062, India.
authors.forename: Vinod B
authors.initials: VB
authors.lastname: Nair
authors.forename: Ramesh
authors.initials: R
authors.lastname: Panchagnula
mesh_terms: D000279:Administration, Cutaneous; D000818:Animals; D001127:Arginine Vasopressin / Q000008:administration & dosage*; D002518:Ceramides / Q000032:analysis; D016503:Drug Delivery Systems; D004347:Drug Interactions; D006860:Hydrogen Bonding; D007478:Iontophoresis / Q000379:methods; D050356:Lipid Metabolism; D008055:Lipids / Q000032:analysis; D010539:Permeability; D051381:Rats; D012867:Skin / Q000187:drug effects* / Q000378:metabolism; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods; D013729:Terpenes / Q000494:pharmacology*
chemical_list: D002518:Ceramides; D008055:Lipids; D013729:Terpenes; D001127:Arginine Vasopressin