Evaluation of calcium alginate gel as electrode material for alternating current iontophoresis of lidocaine using excised rat skin.

Iontophoresis (IOP) is a noninvasive method of delivering medication transcutaneously through the skin. The electrodes used in this method should tightly fit to rough and irregular surfaces and be biologically safe, easy to handle and prepare, and cost-effective. To satisfy these requirements, calcium alginate gel can be a candidate electrode for IOP. Using calcium alginate gel electrodes, we examined whether lidocaine can be effectively transported across an excised rat skin by squarewave alternating current (AC) application. A squarewave AC with either a 70% or 80% duty cycle was continuously applied to 0.5% calcium alginate gel electrodes containing 10% lidocaine at 10 V and 1 kHz for 60 min. Lidocaine concentration was measured using a spectrophotometer and the temperature of the gel was determined. The lidocaine concentrations for AC-IOP at the 70% and 80% duty cycles were significantly higher than that without AC-IOP. Furthermore, the group with the 80% duty cycle showed higher lidocaine concentrations than the group with the 70% duty cycle. The temperatures of all the groups were lower than 28 °C throughout the procedure. In conclusion, the calcium alginate gel can be used as a possible matrix for IOP electrodes.

In vitro evaluation of calcium alginate gels as matrix for iontophoresis electrodes.

Calcium alginate gel has some unique properties, such as the capability to keep the drugs, bioadhesiveness, safety, and low cost. The purpose of this study is to determine whether calcium alginate gel can be used as a matrix of electrodes for iontophoresis (IOP). We measured the concentration of lidocaine transported from calcium alginate gels with various concentrations of alginic acid using an in vitro experimental cell with square-wave alternating current (AC) application. Temperature and pH changes were also determined during AC-IOP. The results revealed that lidocaine was released from calcium alginate gels at concentrations nearly 1.71-fold larger at 5 V, 60 min after AC application than in the case of passive diffusion. Lidocaine transport depended on the alginic acid concentration in the gels. Although there were slight increases in temperature and pH, chemical and thermal burns were not severe enough to be a concern. In conclusion, the calcium alginate gel can be used as a possible matrix for IOP electrodes.