[Transcorneal and transscleral iontophoresis of the dexamethasone phosphate into the rabbit eye]. / Transkorneá1na a transsklerálna ionoforéza dexametazón fosfátu do oka králika.

PURPOSE: To evaluate the efficiency of the dexamethasone phosphate penetration into the rabbit eye after transcorneal and transscleral iontophoresis using a drug loaded hydrogel assembled on a portable iontophoretic Mini Ion device. METHODS: lontophoresis of dexamethasone phosphate was studied in healthy rabbits using drug-loaded disposable HEMA hydrogel sponges and portable iontophoretic device. Corneal iontophoretic administration was performed with electric current of 1 mAmp for 1, 2, and 4 min. In the control group, the dexamethasone was applied in drops into the conjunctival sac. Transconjunctival and transscleral iontophoresis were performed in the pars plana area, through the conjunctiva or directly on the sclera. Dexamethasone concentrations were assayed using HPLC method. To study the anatomical changes after iontophoresis application, histological examinations of corneas excised 5 minutes and 8 hours after the procedure were performed. RESULTS: Dexamethasone levels in the rabbits' corneas after a single transcorneal iontophoresis were up to 38 times higher compared to those obtained after topical eye drops instillation. High drug concentrations were obtained in the retina and sclera 4 hours after transscleral iontophoresis as well. There were no statistically significant differences in the drug concentration after transscleral and tranconjunctival iontophoresis. Histological examination of the corneas after the iontophoresis showed only discrete reversible changes of the epithelium and the stroma. CONCLUSION: A short, low-current, non-invasive iontophoretic treatment using the dexamethasone-loaded hydrogels has a potential clinical value in increasing the drug's penetration into the anterior and posterior segment of the eye.

[Delivery of gentamicin to the rabbit eye using hydrogel and iontophoresis]. / Transport gentamycínu z hydrogélu do oka králika pomocou ionoforézy.

The aim of this study was to evaluate the use of solid hydrogel as a probe for the drug delivery to the rabbit eye upon application of low current iontophoresis. Hydroxyethyl methacrylate (HEMA), cross-linked with ethylenglycol dimethacrylate (EGDMA) were prepared to form solid hydrogels. The concentrations of gentamicin sulfate in different segments of rabbit eye after transconjunctival and transscleral iontophoresis were also studied. For iontophoresis we used a portable Mini Ion device (designed at Hebrew University of Jerusalem) and applied a current from 0 mA to 1.5 mA for pre-set period from 30 to 120 seconds and after application the concentrations of gentamicin in cornea were assayed. The rabbits in control group were treated with fortified gentamicin eye-drops (concentration 1.4 %). The highest concentration of gentamicin sulfate was reached after iontophoresis with current intensity of 1.5 mA applied for 60 s. High gentamicin concentration were found in the retina and in the sclera four hours after transscleral iontophoresis, the lowest concentration was obtained in vitreous. The delivery of gentamicin to the eye via iontophoresis with solid HEMA/EGDMA hydrogels seems to be promising method achieving high concentrations of the drug in the eye tissue.