ABSTRACT
The treatment of ocular disorders is challenging due to the anatomical and physiological constraints. Drug elimination via precorneal tear clearance, blinking, and nasolacrimal drainage restricts the entry of the drug molecule to the anterior segment of the eye. In addition, the presence of efux pumps, such as P-glycoprotein (P-gp), multidrug resistance-associated proteins, and breast cancer-resistant proteins (BCRPs), also limit the ocular bioavailability of drugs, such as antibiotics, steroids, and antitumor agents. Drug delivery to the posterior segment of the eye is challenged by barriers such as the inner and outer blood-retinal barriers (BRBs) and efux pumps.
