MRI in ocular drug delivery

Abstract

Conventional pharmacokinetic methods for studying ocular drug delivery are invasive and cannot be conveniently applied to humans. The advancement of MRI technology has provided new opportunities in ocular drug-delivery research. MRI provides a means to non-invasively and continuously monitor ocular drug-delivery systems with a contrast agent or compound labeled with a contrast agent. It is a useful technique in pharmacokinetic studies, evaluation of drug-delivery methods, and drug-delivery device testing. Although the current status of the technology presents some major challenges to pharmaceutical research using MRI, it has a lot of potential. In the past decade, MRI has been used to examine ocular drug delivery via the subconjunctival route, intravitreal injection, intrascleral injection to the suprachoroidal space, episcleral and intravitreal implants, periocular injections, and ocular iontophoresis. In this review, the advantages and limitations of MRI in the study of ocular drug delivery are discussed. Different MR contrast agents and MRI techniques for ocular drug-delivery research are compared. Ocular drug-delivery studies using MRI are reviewed.

In vitro and in vivo ocular safety and eye surface permanence determination by direct and Magnetic Resonance Imaging of ion-sensitive hydrogels based on gellan gum and kappa-carrageenan

“…For MRI, anesthesia was used only for gel instillation and after 2 h to do the MRI. Due to the large amount of water retained by the polymer into the gel, the incorporation of MRI probes was not necessary because water increased the signal intensity in MRI T2 allowing the visualization of the gel [34]. MRI studies were conducted in a horizontal 9.4 T magnetic resonance (Bruker BioSpin, Ettlingen, Germany) 20 cm diameter hole with gradients of 440 mT/m.…”

Ocular Delivery of pRNA Nanoparticles: Distribution and Clearance After Subconjunctival Injection

“…Ocular pharmacokinetic studies have provided useful information on the distribution of drugs in the eye and in the development of novel drug delivery methods. In addition to conventional pharmacokinetic approaches of tissue dissection, methods such as microdialysis (13), fluorophotometry (14), and magnetic resonance imaging (MRI) (15) have been used in the studies of ocular pharmacokinetics and to determine the routes of drug delivery and clearance after periocular, intrascleral, and intravitreal administration. Despite these recent efforts in studying the mechanisms and pharmacokinetics of ocular drug delivery, the distribution and clearance after ocular drug delivery are still difficult to predict (16).…”

Ocular Pharmacokinetic Study Using T1 Mapping and Gd-Chelate- Labeled Polymers

“…The investigation of ocular pharmacokinetics by traditional methods is invasive and can severely disturb the biodistribution of pharmaceuticals during dissection in animals (10). Recent studies have demonstrated the feasibility of MRI for noninvasive monitoring of the biodistribution of pharmaceuticals in the body in drug delivery research (9,11–13).…”