Abstract
Purpose: :
Iontophoresis is a proven safe non-invasive drug delivery method at currents up to 2.5 mA. The objective of this study was to determine safety of consecutive daily iontophoretic treatments with currents up to 10 mA delivered in New Zealand White rabbits. The use of higher currents could enhance drug delivery efficiency and decreased application time.
Methods: :
A sterile dosing solution of 100 mM sodium citrate buffer (pH 5.7) was used for ocular iontophoresis in this study. Animals were anesthetized with standard ketamie/xylazine cocktail and treated with three daily iontophoretic doses of 30 mA-min (10 mA for ~ 3 min). Animals treated with iontophoretic current were compared to no current controls (0 mA for ~3 min). Ocular exams, including toxicological assessment, slit-lamp examination and fluorescein staining, were performed on all eyes before and after dosing on each day and after a 24 hour to 14-day recovery period. Upon sacrifice, eyes were processed for microscopy and were histopathologically evaluated. In addition, electroretinograms (ERG) were performed on dark-adapted rabbits before the study and immediately after treatment on Day 1 and Day 3.
Results: :
There were no significant macroscopic toxicological effects following three consecutive 10 mA iontophoretic doses (30 mA-min) on the cornea, conjunctiva, or iris. Slight fluorescein staining was observed in both the treatment and control groups; however, there were no differences in fluorescein staining between pre- and post- iontophoretic treatment. Histopathological evaluation revealed no significant clinical abnormalities in the eyes that received iontophoretic current when compared to no current controls. No statistically significant changes in ERGs of rabbits were noted in any of the eyes treated with iontophoretic current compared to controls.
Conclusions: :
These data indicate that three consecutive daily ocular iontophoretic treatments at currents up to 10 mA (at doses up to 30 mA-min) had no detrimental effects on ocular tissues or retinal function.
Keywords: sclera • ocular irritancy/toxicity testing • electroretinography: non-clinical