J P Howard1, T R Drake, D L Kellogg. 1. Department of Medicine, University of Texas Health Science Center, San Antonio 78284-7756, USA.
Abstract
OBJECTIVE: The duration of direct current (DC) iontophoresis is limited to 10- to 15-minute periods because of electrochemical burns from hydrogen and hydroxide ions generated by the DC current. A new iontophoretic device, the Lectro Patch, uses a low-frequency alternating current (AC). AC current is theorized to generate H+ ions during one phase and OH- when the current reverses polarity, thus possibly neutralizing pH changes and avoiding burns. This study examined this possibility and evaluated drug delivery with AC iontophoresis, using hydroxocobalamin. DESIGN: A known amount of hydroxocobalamin dissolved in 6mL of water was loaded in Lectro Patches, two of which were then taped on the forearms of 10 patient volunteers. One patch was activated to deliver drug by AC iontophoresis. The second patch was not activated and served as a control for delivery by diffusion. Trials were run for 2 and 4 hours, with both 1,000 micrograms/mL and 2,000 micrograms/mL concentrations. SETTING: Study was conducted with inpatients in an extended care setting using volunteers. MAIN OUTCOME MEASURES: Amounts of hydroxocobalamin remaining in the Lectro Patches after iontophoresis were assayed by spectrophotometry. Data were analyzed by ANOVA. RESULTS: No burns occurred. Significantly greater losses occurred with 4 hours of iontophoresis than with 2 hours (p < 0.05). There was no significant effect of changing the concentration of hydroxocobalamin. CONCLUSIONS: AC iontophoresis avoids electrochemical burns; charged drugs can be delivered by AC iontophoresis; and delivery of drug increases with duration of application.
OBJECTIVE: The duration of direct current (DC) iontophoresis is limited to 10- to 15-minute periods because of electrochemical burns from hydrogen and hydroxide ions generated by the DC current. A new iontophoretic device, the Lectro Patch, uses a low-frequency alternating current (AC). AC current is theorized to generate H+ ions during one phase and OH- when the current reverses polarity, thus possibly neutralizing pH changes and avoiding burns. This study examined this possibility and evaluated drug delivery with AC iontophoresis, using hydroxocobalamin. DESIGN: A known amount of hydroxocobalamin dissolved in 6mL of water was loaded in Lectro Patches, two of which were then taped on the forearms of 10 patient volunteers. One patch was activated to deliver drug by AC iontophoresis. The second patch was not activated and served as a control for delivery by diffusion. Trials were run for 2 and 4 hours, with both 1,000 micrograms/mL and 2,000 micrograms/mL concentrations. SETTING: Study was conducted with inpatients in an extended care setting using volunteers. MAIN OUTCOME MEASURES: Amounts of hydroxocobalamin remaining in the Lectro Patches after iontophoresis were assayed by spectrophotometry. Data were analyzed by ANOVA. RESULTS: No burns occurred. Significantly greater losses occurred with 4 hours of iontophoresis than with 2 hours (p < 0.05). There was no significant effect of changing the concentration of hydroxocobalamin. CONCLUSIONS:AC iontophoresis avoids electrochemical burns; charged drugs can be delivered by AC iontophoresis; and delivery of drug increases with duration of application.