Effective permeation of 2.5 and 5% lidocaine hydrochloride in human skin using iontophoresis technique

BackgroundLidocaine Hydrochloride (HCL) is one of the commonest topical local anesthetic drugs. The permeation of the lidocaine can be enhanced by iontophoresis (IOP). The purpose of this study was to evaluate the permeability of 2.5 and 5% lidocaine permeation in ex vivo human skin using different IOP waveform. MethodsContinuous and modulated IOP at the current density of 0.5 mA/cm(2) were applied across human skin (n = 3) in donor chamber of vertical diffusion cell at 2.5 and 5% lidocaine concentration. High Performance Liquid Chromatography was used to determine lidocaine concentration. ResultsFindings revealed that lidocaine concentration increased effectively in a time-dependent manner in both modulated and continuous IOP at 2.5 and 5% lidocaine concentration. Compared to the passive group, the flux of lidocaine with modulated and continuous IOP were higher of about six and ten-fold, respectively. However, no significant difference was observed between continuous and modulated IOP groups at both lidocaine concentrations. At 2.5% lidocaine concentration, the permeation time taken by modulated and continuous IOP to attain therapeutic levels of 142 and 164 g/cm(2), respectively, was approximately 10 minutes. At 5% lidocaine, the therapeutic permeation of 129 and 147 g/cm(2), respectively, was achieved at approximately 5 minutes after applying iontophoresis waveform. ConclusionStudy shows that modulated IOP can be a promising alternative method in clinical settings aside from continuous IOP. Based on the clinical requirements, IOP can be used at 2.5 and 5% lidocaine concentration depending on need of relatively short or very short onset action.