Newer Approaches for Optimal Bioavailability of Ocularly Delivered Drugs: Review

Abstract

Eye diseases can cause discomfort and anxiety in patients, with the ultimate fear of loss of vision and facial disfigurement. Many regions of the eye are relatively inaccessible to systemically administered drugs and, as a result, topical drug delivery remains the preferred route in most cases. Drugs may be delivered to treat the precorneal region for conjunctivitis and blepharitis, or to provide intraocular diseases such as glaucoma, uveitis, and cytomegalovirus retinitis. Most of the ophthalmic formulation strategies aim at maximizing ocular drug permeability through prolongation of the drug residence time in the cornea and conjunctival sac, as well as minimizing precorneal drug loss. The conventional topical ocular drug delivery systems show drawbacks such as increased precorneal elimination and high variability in efficacy. Attempts have been made to overcome these problems and enhance ocular bioavailability by the development of newer drug delivery systems. This review is concerned with classification, recent findings and applications and biocompatibility of newer drug delivery systems for the treatment of ocular diseases.

Platelet Derivatives in Regenerative Medicine: An Update

“…Unfortunately, the presence of fibrotic tissue at the anterior surface of the eye after an injury or a surgery may induce corneal opacification (corneal haze) [120] and may lead to surgical failure. Different approaches to regenerate the ocular surface and to treat the scar formation have been attempted [121]. Results demonstrated that different blood formulations (whole plasma and PRP) showed similar biological effects on proliferation and migration of keratocytes and conjunctival fibroblast cells and on the inhibition of myofibroblastic phenotype to reduce scarring [110].…”

Successfully Improving Ocular Drug Delivery Using the Cationic Nanoemulsion, Novasorb

“…Many attempts have been made to prolong the exposure time of topically applied ocular treatments and to improve their bioavailability, therapeutic efficacy, or patient compliance by reducing the number of required administrations [8–10]. Hydrogels, now widely used in the ophthalmic pharmaceutical industry, have enabled, for example, a decrease in the frequency of timolol administrations from two instillations daily to only one.…”

A New Preparation Method for Ophthalmic Drug Nanoparticles

“…Superficial barriers impede direct and systemic drug access to the specific site of action. Drug loaded nanoparticles show favorable biological properties including prolonged residence time for eye drops, decreased toxicity, and increased ability of the drug to penetrate into the deeper layers of the ocular structure and aqueous humor thus minimizing precorneal drug loss caused by rapid tear fluid turnover [6,26]. Techniques were planned to transform nanoparticles from lipophilic to hydrophilic and to down-regulate irritation to the eye.…”