Determination of Thiolated Chitosan as Nanocarriers for Ocular Drug Delivery

Drug delivery through the ocular route now-a-days became more interesting and challenging due to its complex anatomical structure. Despite of numerous efforts by the formulating scientists all over the world there are many challenges need to be overcome in making the drug delivery through the corneal route. The main issue with conventional dosage forms is poor ocular bioavailability due to short ocular residence times caused by anatomical and pathophysiological barriers in the eye. As a result, substantial work has gone into creating nanotechnology-based drug delivery methods that increase precorneal residence time to improve ocular bioavailability of medicines. Polymers containing thiol groups have much higher adhesive properties than polymers that are generally thought to be mucoadhesive. Chitosan and its derivatives are excellent polymeric biomaterials that have a variety of uses in drug delivery, particularly through the ocular route. Thiolated derivatives (thiomers) of chitosan produced via immobilization of thiol groups on the primary amino groups of chitosan backbone has improved its mucoadhesive properties by establishment of electrostatic interactions with mucin and enhanced permeability and anti-protease activity. Moreover, it is also biocompatible, biodegradable, and non-toxic. Many drugs and therapeutics can be administered via nanoparticulate form also or as an in-situ gel forming systems through the ocular route using Thiolated chitosan. The main objective of this chapter is to provide an insight into the various approaches using Thiolated chitosan as nanocarrier for ocular drug delivery by summarizing recent findings and its applications in the field of ocular drug delivery.