Background: Iontophoresis is one of the widely used noninvasive and painless transdermal drug delivery technique.Objective: Transdermal delivery of Lidocaine Hydrochloride using continuous and modulated iontophoresis were evaluated across human skin ex-vivo and further assessed for skin tolerance in-vivo in the Swiss albino mice.Methods: Continuous DC was modified into modulated DC by introducing ON-OFF time in continuous DC. Iontophoresis studies were conducted on human skin samples for 60 min.Results: Drug permeation of 2% lidocaine HCl was enhanced in current density-, duty cycle- and time-dependent manner across human skin. The lidocaine HCl concentration obtained with modulated DC and continuous DC iontophoresis were about three-fold and four-fold higher than passive group respectively for all current densities across human skin. Continuous DC iontophoresis was found to be more effective than modulated DC. However, no significant difference was observed in transport of lidocaine HCl between 75% and 100% (continuous) duty cycle at all current density. Further, in-vivo reversibility studies with mice confirmed that modulated iontophoresis was well tolerated by the tissue and the injury caused is transient and reversible.Conclusion: For clinical application, modulated DC iontophoresis with 75% duty cycle at 0.5 mA/cm2 current density would be recommended.
Keywords: Iontophoresis; human skin; lidocaine hydrochloride; transdermal delivery.