Transcorneal and transscleral iontophoresis of dexamethasone phosphate using drug loaded hydrogel
ABSTRACT To evaluate dexamethasone penetration to the eye after a short transcorneal and transscleral iontophoresis using a drug loaded hydrogel assembled on a portable iontophoretic device.
Iontophoresis 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 a current intensity of 1 mA for 1 and 4 min. Transconjunctival and transscleral iontophoresis were performed twice for 2 min at two near places in the pars-plana area, on the conjunctival membrane or directly on the sclera. Dexamethasone concentrations were assayed using HPLC.
Dexamethasone levels in the rabbit cornea after a single transcorneal iontophoresis for 1 min were up to 30 fold higher compared to those obtained after frequent eye drop instillation. Also, high drug concentrations were obtained in the retina and sclera 4 h after transscleral iontophoresis.
A short low current non-invasive iontophoretic treatment using dexamethasone-loaded hydrogels has potential clinical value in increasing drug penetration to the anterior and posterior segments of the eye.
- SourceAvailable from: Eun-Kee Jeong
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- "Results from previous transscleral iontophoresis studies are generally consistent with this trend. For example, iontophoresis studies of dexamethasone phosphate, methylprednisolone, amikacin, cefazolin, ticarcillin, and gentamicin showed an increase in delivery into the eye when the electric current of iontophoresis was increased (Barza et al., 1986;Behar-Cohen et al., 2002;Vollmer et al., 2002;Eljarrat-Binstock et al., 2005). In a study of the effects of current density upon iontophoretic delivery of fluorescein into the posterior segment of the eye, electric current density was shown to significantly affect transscleral delivery when the current density was above 40 mA/cm 2 (Maurice, 1986). "
ABSTRACT: Previously, transscleral and transcorneal iontophoretic delivery was studied and compared to passive delivery and intravitreal injection using nuclear magnetic resonance imaging (MRI). The objective of the present study was to employ MRI to further investigate the factors affecting transscleral iontophoretic delivery. In the present study, anodal and cathodal constant current transscleral iontophoresis were conducted with excised sclera in side-by-side diffusion cells in vitro and with rabbits in vivo. The total current and duration of application were 2 and 4mA (current density 10 and 20mA/cm(2)) and 20-60min, respectively. The delivery and distribution of the model permeants manganese ion (Mn(2+)) and manganese ethylenediaminetetraacetic acid complex (MnEDTA(2-)) into the eye during iontophoresis were determined with MRI and compared with the results obtained in previous studies of subconjunctival injection and passive delivery. Both anodal and cathodal iontophoresis provided significant enhancement in ocular delivery compared to passive transport in the in vitro and in vivo experiments. Transscleral iontophoretic delivery was related to the position and duration of the iontophoresis application in vivo. Permeants were observed to be delivered primarily into the anterior segment of the eye when the pars plana was the application site. Extending the duration of iontophoresis at this site allowed the permeants to be delivered into the vitreous more deeply and to a greater extent than when the application site was at the back of the eye near the fornix. The present results show that electrode placement was an important factor in transscleral iontophoresis, and the ciliary body (pars plana) was determined to be the pathway of least resistance for iontophoretic transport. These new findings continue to support the utility of MRI as a noninvasive technique in ocular drug delivery research and testing.International Journal of Pharmaceutics 05/2007; 335(1-2):46-53. DOI:10.1016/j.ijpharm.2006.11.001 · 3.65 Impact Factor
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ABSTRACT: Iontophoresis as a non-invasive technique for ocular drug delivery has been investigated for many years. This paper provides an overview of the approaches currently used in the development of the ocular iontophoretic device, the essential features of this procedure and the reported toxicity. This review focuses on the experimental results after transcorneal and transscleral iontophoresis of different drugs, emphasizing the current density applied and the treatment duration used by the investigators.Journal of Controlled Release 03/2006; 110(3):479-89. DOI:10.1016/j.jconrel.2005.09.049 · 7.26 Impact Factor