Transdermal Delivery Using a Novel Electrochemical Device, Part 1: Device Design and In Vitro Release/Permeation of Fentanyl

A new type of electrochemical transdermal patch has been investigated using release/permeation experiments with excised nude mouse skin. The patch comprises a drug-containing hydrogel sandwiched between two electrodes that are arranged parallel to the skin surface. The objective was to determine the mechanism of working of enhanced flux for the drug fentanyl when low voltages are applied. The results indicate that a voltage-induced hydrolysis of the water present in the patch's hydrogel occurs. This causes a pH shift that results in deprotonization of the fentanyl and hence enhanced release/permeation. The enhanced flux is up to approximately 30 μg/(cm2 h) over 20 h and requires only a low-voltage application over a duration of just 60 s. Because the enhancement mechanism occurs in the patch and not in the skin, the potential for substantially reduced skin irritation compared with iontophoresis is given. © 2011 Wiley Periodicals, Inc. and the American Pharmacists Association.