Novel strategies for anterior segment ocular drug delivery

Abstract

Research advancements in pharmaceutical sciences have led to the development of new strategies in drug delivery to anterior segment. Designing a new delivery system that can efficiently target the diseased anterior ocular tissue, generate high drug levels, and maintain prolonged and effective concentrations with no or minimal side effects is the major focus of current research. Drug delivery by traditional method of administration via topical dosing is impeded by ocular static and dynamic barriers. Various products have been introduced into the market that prolong drug retention in the precorneal pocket and to improve bioavailability. However, there is a need of a delivery system that can provide controlled release to treat chronic ocular diseases with a reduced dosing frequency without causing any visual disturbances. This review provides an overview of anterior ocular barriers along with strategies to overcome these ocular barriers and deliver therapeutic agents to the affected anterior ocular tissue with a special emphasis on nanotechnology-based drug delivery approaches.

FIG. 1.

Anterior ocular tissues and fluid. Color images available online at www.liebertpub.com/jop

FIG. 2.

Different layers of cornea: (1) Outer epithelium (comprising superficial cells, wing cells, and basal cells), (2) Bowman's layer, (3) Stroma, (4) Descemet's membrane, and (5) Endothelium. Reproduced and modified with permission from Barar et al.

FIG. 3.

Caveolin-1 immunofluorescence in HCE (human corneal epithelial cell line) and IOBA-NHC (conjunctival epithelial cell line) cells after HA-CSO NP incubation. Merged images showed colocalization of HA-CSO NP with caveolin (staining at arrowheads). Reproduced from Contreras-Ruiz et al. HA, hyaluronic acid; HA-CSO NP, hyaluronic acid-chitosan oligomer-based nanoparticle. Color images available online at www.liebertpub.com/jop

FIG. 4.

Anterior chamber pharmacokinetic study with voclosporin in New Zealand white rabbits with single topical drop administration of mixed nanomicellar formulation.