Influence of Asymmetric Donor–Receiver ion Concentration Upon Transscleral Iontophoretic Transport

Li, S.Kevin; Zhang, Yanhui; Zhu, Honggang; Higuchi, William I.; White, Henry S.

doi:10.1002/jps.20293

Cited by 28 publications

(51 citation statements)

References 21 publications

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“…However, during transscleral iontophoresis, the present results suggest counterion influence upon transport under an electric field. It is believed that when high concentration of the permeants was used, the higher ion concentration in the donor chamber than that in the receiver can lead to the situation that permeant fluxes become no longer proportional to the concentration of the permeants in the donor (Li et al, 2005), and lower normalized fluxes (the apparent permeability coefficients) would be observed. Fig.…”

Section: In Vitro Resultsmentioning

confidence: 99%

“…Electroporation describes barrier alteration that increases the intrinsic permeability of the membrane. According to a previous in vitro study (Li et al, 2005), the effects of electroosmosis upon transscleral iontophoretic transport of small ionic permeants are secondary. The results in a recent MRI study suggest that electroporation of a transscleral tissue barrier, possibly of the retinal epithelial membrane, is a flux enhancing mechanism of transscleral iontophoresis (unpublished data).…”

Section: Factors Affecting Transscleral Iontophoresismentioning

confidence: 99%

“…Iontophoresis generally enhances drug delivery by three mechanisms: electrophoresis, electroosmosis, and electroporation (Li et al, 2005;Eljarrat-Binstock and Domb, 2006). Electrophoresis is the facilitation of the movement of ionic species by the applied electric field.…”

Section: Factors Affecting Transscleral Iontophoresismentioning

confidence: 99%

“…A two-chamber side-by-side diffusion cell system with excised rabbit sclera was used in the experiments (Li et al, 2004b(Li et al, ,2005. Each compartment of the diffusion cell has a 2-ml volume and an effective diffusional area of around 0.2 cm 2 .…”

Section: In Vitro Transport Experimentsmentioning

confidence: 99%

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Examination of penetration routes and distribution of ionic permeants during and after transscleral iontophoresis with magnetic resonance imaging

Molokhia

Jeong

Higuchi

et al. 2007

International Journal of Pharmaceutics

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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 4 mA (current density 10 and 20 mA/cm 2 ) and 20-60 min, 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.

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Section: In Vitro Resultsmentioning

confidence: 99%

Section: Factors Affecting Transscleral Iontophoresismentioning

confidence: 99%

Section: Factors Affecting Transscleral Iontophoresismentioning

confidence: 99%

Section: In Vitro Transport Experimentsmentioning

confidence: 99%

See 2 more Smart Citations

Examination of penetration routes and distribution of ionic permeants during and after transscleral iontophoresis with magnetic resonance imaging

Molokhia

Jeong

Higuchi

et al. 2007

International Journal of Pharmaceutics

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show abstract

“…Iontophoresis experiments were carried out in a wellstirred two-chamber side-by-side diffusion cell system as described previously (15). The effective diffusion area of the diffusion cells was around 0.2 cm 2 , and each compartment of the diffusion cell had a 2-ml volume.…”

Section: Theory and Equationsmentioning

confidence: 99%

Enhanced Transscleral Iontophoretic Transport with Ion-Exchange Membrane

Zhu

Higuchi

2006

Pharm Res

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Assessment of trans‐scleral iontophoresis delivery of lutein to the human retina

Lombardo

Villari

Micali

et al. 2017

Journal of Biophotonics

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The efficacy of novel scleral iontophoresis device for in situ delivery of lutein to the human retina was assessed by Resonance Raman spectroscopy (RRS) technique. Eight human donor eye globes were used for experiments, 6 of which underwent trans-scleral iontophoresis delivery of lutein and the other 2 were used as controls. The scleral iontophoresis applicator was filled with liposome-enriched 0.1% lutein solution and the generator's current was set at 2.5 mA and delivered for 4 min. A custom RRS setup was used for detecting lutein in the inner sclera, choroid, retinal periphery and macula of treated samples and controls. Forty minutes after iontophoresis, the inner sclera, choroid and retinal periphery were greatly enriched with lutein (P < .05); no lutein was found in the same ocular regions of non-treated samples. In the same period, the average concentration of lutein in the macula (4.8 ± 1.7 ng/mm ) of treated samples was 1.3 times greater than controls (3.7 ± 1.0 ng/mm ; P = .4). Scleral iontophoresis was shown to be effective in delivering lutein to the human retina. Future studies will aim at assessing if this therapeutic strategy is valuable to enrich the macular pigment in human subjects.

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Influence of Asymmetric Donor–Receiver ion Concentration Upon Transscleral Iontophoretic Transport

Cited by 28 publications

References 21 publications

Examination of penetration routes and distribution of ionic permeants during and after transscleral iontophoresis with magnetic resonance imaging

Examination of penetration routes and distribution of ionic permeants during and after transscleral iontophoresis with magnetic resonance imaging

Enhanced Transscleral Iontophoretic Transport with Ion-Exchange Membrane

Assessment of trans‐scleral iontophoresis delivery of lutein to the human retina

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