Transscleral Iontophoresis Does Not Effect Ocular Temperature in Rabbits

Abstract

Purpose: : Ocular iontophoretic delivery of drugs is an efficient non-invasive alternative for treatment of ocular diseases. The technology involves applying an electrical current to an ionizable drug product in order to increase its mobility across the ocular tissues. This study was designed to evaluate if multiple iontophoretic treatments could have any effect on ocular temperature.

Methods: : Four New Zealand White rabbits were anesthetized with standard ketamine/xylazine cocktail. Five thermocouples were surgically implanted on each animal to record temperature of the conjunctival cul-de-sac, at 50% depth in the cornea (intrastromal), in the anterior chamber, vitreous cavity, and subcutaneous (body temperature). Room temperature was also recorded. The ocular iontophoretic applicators were loaded with a 40 mg/mL dexamethasone phosphate solution. Right eyes received an iontophoretic treatment of 28 mA-min (4.0 mA for ~7 min) and left eyes, a sham treatment (no current for ~7 min). Three consecutive sham or active treatments were given with a 3 - 5 minute recovery between each treatment .

Results: : Ocular temperatures recorded during the 28 mA-min iontophoretic treatments were not significantly different than those recorded during the sham iontophoretic treatments (no current control). In all cases, the temperature of the corneal stroma, anterior chamber, and posterior chamber remained well below body temperature.

Conclusions: : These results indicate that multiple iontophoretic treatments at doses up to 28 mA-min do not alter ocular tissue temperature even when performed on the same daySupport: EyeGatePharma, Florida Lions Eye Bank, NIH center grant P30 EY14801, an unrestricted grant from Research to Prevent Blindness, the Henri and Flore Lesieur Foundation (JMP).

Keywords: sclera • ocular irritancy/toxicity testing • corticosteroids