Effect of iontophoresis and penetration enhancers on transdermal absorption of metopimazine

Background: Metopimazine is an antiemetic drug already used by oral and rectal administration. It would be interesting to develop a new formulation for a transdermal administration. Objective: The objective of this study was to determine the influence of iontophoresis on the metopimazine transdermal absorption and the possible synergistic enhancement with chemical enhancers. Methods: Transdermal transport of metopimazine was studied in vitro in a Franz cell, with pig skin according to the following protocol: 1 h of iontophoresis followed by 7 h of passive diffusion. Different current densities were applied: 0, 0.125, 0.25 and 0.5 mA/cm(2). Chemical enhancers used as solvent dilution were ethanol, propylene glycol and isopropyl myristate. Metopimazine was assayed by HPLC. Fourier transform infrared spectroscopy was used to determinate the interaction between chemical enhancers and stratum corneum. Results: The iontophoresis has increased the percutaneous absorption of metopimazine and has decreased the tag time with 3.85 +/- 0.90 mu g/(cm(2) h) and 1.9 h for 0.5 mA/cm(2) and with 0.27 +/- 0.20 mu g/(cm(2) h) and > 8 h for passive diffusion. Transdermal transport has been increased with current density and with isopropyl myristate and was not modified by ethanol or propylene glycol. Conclusion: Results indicated that iontophoresis is an effective method for transdermal administration of metopimazine. (c) 2008 Japanese Society for Investigative Dermatology. Published by Elsevier Ireland Ltd. All rights reserved.