Nanocrystal for ocular drug delivery: hope or hype

Abstract

The complexity of the structure and nature of the eye emanates a challenge for drug delivery to formulation scientists. Lower bioavailability concern of conventional ocular formulation provokes the interest of researchers in the development of novel drug delivery system. Nanotechnology-based formulations have been extensively investigated and found propitious in improving bioavailability of drugs by overcoming ocular barriers prevailing in the eye. The advent of nanocrystals helped in combating the problem of poorly soluble drugs specifically for oral and parenteral drug delivery and led to development of various marketed products. Nanocrystal-based formulations explored for ocular drug delivery have been found successful in achieving increase in retention time, bioavailability, and permeability of drugs across the corneal and conjunctival epithelium. In this review, we have highlighted the ocular physiology and barriers in drug delivery. A comparative analysis of various nanotechnology-based ocular formulations is done with their pros and cons. Consideration is also given to various methods of preparation of nanocrystals with their patented technology. This article highlights the success achieved in conquering various challenges of ocular delivery by the use of nanocrystals while emphasizing on its advantages and application for ocular formulation. The perspectives of nanocrystals as an emerging flipside to explore the frontiers of ocular drug delivery are discussed.

The Effect of Silica Nanoparticles on Human Corneal Epithelial Cells

“…If a drug can penetrate the full thickness of cornea and reach the anterior chamber in high concentration, then further diffusion into the posterior chamber should occur easily. Recently, it was suggested that this long challenging problem could be overcome with the use of nano-based drug carriers56. Several recent reports of successful intraocular drugs or gene deliveries by various nanoparticles further increased such expectations18192021222324.…”

“…To enhance ocular drug penetration, nanoparticle based drug delivery systems have been intensively investigated with promising results456. Amorphous silica nanoparticles (SiNPs) are some of the most promising nanoparticle systems for ocular drug delivery.…”

Species differences in ocular pharmacokinetics and pharmacological activities of regorafenib and pazopanib eye‐drops among rats, rabbits and monkeys

“…In addition, nano‐crystals are beneficial for long time retainment on eye surface. Nano‐crystals can be retained in the cul‐de‐sac and its large surface area allows long‐term adhesion to the eye surface …”

Stimulus‐Responsive Hydrogel for Ophthalmic Drug Delivery

“…Despite the distinct advantages of local therapies, a highly efficient ophthalmic drug delivery approach remains one of the most challenging tasks for pharmaceutical formulators and scientists because of various physiological barriers (Figure ) . In the anterior segment of the eye, the corneal‐aqueous humor barrier, physiological blinking, and tear drainage are dominant factors for rapid drug clearance after topical instillation .…”