Application of iontophoresis in ophthalmic practice: an innovative strategy to deliver drugs into the eye

Abstract

Delivery of drugs to special locations of ocular lesions, while minimizing systemic and local toxic effects, is recognized as a critical challenge in the ophthalmic practice. The special anatomy and physiology barriers within the eyeball entail effective drug delivery systems. Emerging attempts in drug delivery has led to developments in ocular iontophoresis, which acts as a noninvasive technology to enhance drug penetration using a small electric current. This technique offers greater flexibility to deliver desired drug dose in a controlled and tolerable manner. In previous studies, this technique has been testified to deliver antibiotics, corticoid, proteins and other gene drugs into the eye with the potency of treating or alleviating diverse ophthalmological diseases including uveitis, cataract, retinoblastoma, herpes simplex and cytomegalovirus retinitis (CMVR), etc. In this review, we will introduce the recent developments in iontophoresis device. We also summarize the latest progress in coulomb controlled iontophoresis (CCI), hydrogel ionic circuit (HIC) and EyeGate II delivery system (EGDS), as well as overview the potential toxicity of iontophoresis. We will discuss these factors that affect the efficacy of iontophoresis experiments, and focus on the latest progress in its clinical application in the treatment of eye diseases.

Application of Hydrogels in the Device of Ophthalmic Iontophoresis: Theory, Developments and Perspectives

“…Inert electrodes such as platinum electrodes are always used in iontophoresis. During the ionization process using inert electrodes, the PH of the anode will decrease progressively, while the PH of the cathode will increase over time [2].…”

“…At the same time, Behar Cohen et al have formulated a safety procedure for transscleral iontophoresis with current intensity smaller than 50 mA/cm 2 [4]. Within the scope of this safety procedure, many studies did not find any evidence of inflammation or toxicity in the intraocular tissues during iontophoresis treatment [2]. However, safe current intensity exceeding the recommended range would pose a potential risk of injury.…”

“…Several complicated biological barriers make it very challenging to deliver drugs to the lesion within the eyeball. Thus far, the commonly used methods of ophthalmic drug delivery, such as topical drug delivery, systemic drug delivery, vitreous cavity injection, and change of drug dosage or structure, have their own drawbacks [2,3]. Delivering drugs to the eye non-invasively remains an important problem in clinical practice.…”

“…When the size of the drug approaches the mesh size, the rate of drug release slows down. Once the drug diameter is larger than the mesh size, it is physically encapsulated in the mesh (2). The mild preparation conditions and water rich content make hydrogels an ideal material to preserve the activity of small molecule, peptides, and protein drugs over extended times.…”

Hyaluronic acid-based nanoparticles to deliver drugs to the ocular posterior segment

“…Although the eye is an easy-to-reach body part, drug administration to the posterior portion remains a challenge (Alshaikh et al., 2022 ). Topical application is a convenient and safe method for delivering ocular medications to the surface of the eye (Wei et al., 2023 ). Due to the various eye barriers, it is still challenging for topical administration to efficiently transfer drugs to the posterior of the eye.…”