6 - Biocomposites in ocular drug delivery

Abstract

There has been a high clinical demand for increasing the delivery efficiency of therapeutic molecules in the anterior and posterior segments of the eye. Conventional eye drops are mostly used for the treatment of ocular diseases. However, the main drawback associated with the conventional pharmacotherapy is low corneal penetration with consequent poor ocular bioavailability (∼5%). This low bioavailability is due to quick tear turnover, nasolachrymal drainage, metabolic degradation, and limited cul-de-sac volume to accommodate the desired amount of ophthalmic solution. Hence, the eye drops are often less effective and require frequent instillation. However, frequent administration of drugs might cause undesirable side effects, resulting from the systemic absorption of drugs through the nasolachrymal duct. The frequent dosing often leads to patient noncompliance and results in subtherapeutic drug concentration in the ocular surface. To overcome the limitations associated with ophthalmic drops, various novel delivery strategies have been suggested. Owing to nontoxic, biodegradable, mucoadhesive, and biocompatible properties, biopolymers are being preferred for the design of composite materials that could enhance the precorneal retention time, control delivery of drug and enhance the corneal absorption of drugs. This chapter covers the drug delivery attributes of various biopolymer-based composite systems such as nanocomposite hydrogels, solid lipid nanoparticles, in situ forming hydrogels, and ocular inserts.