Abstract
The main inconvenience of conventional eye drops is the rapid washout of the drugs due to nasolacrimal drainage or ophthalmic barriers. The ocular drug bioavailability can be improved by either prolonging retention time in the cul-de-sac or by increasing the ocular permeability. The focus of this review is to highlight some chitosan-based drug delivery approaches that proved to have good clinical efficacy and high potential for use in ophthalmology. They are exemplified by recent studies exploring in-depth the techniques and mechanisms in order to improve ocular bioavailability of the active substances. Used alone or in combination with other compounds with synergistic action, chitosan enables ocular retention time and corneal permeability. Associated with other stimuli-responsive polymers, it enhances the mechanical strength of the gels. Chitosan and its derivatives increase drug permeability through the cornea by temporarily opening tight junctions between epithelial cells. Different types of chitosan-based colloidal systems have the potential to overcome the ocular barriers without disturbing the vision process. Chitosan also plays a key role in improving corneal wound healing by stimulating the migration of keratinocytes when it is used alone or in combination with other compounds with synergistic action.
Highlights
The major difficulty in treating ocular diseases is to provide and maintain an optimal ocular concentration of the drug for a long period of time [1]
The results showed that the addition of Hydroxypropyl methylcellulose (HPMC) to chitosan-based formulations increased the chitosan-based formulations increased the viscosity following contact with simulated lacrimal viscosity following contact with simulated lacrimal fluid [34]
A thermosensitive gel based on chitosan, gelatin and disodium β-glycerophosphate was developed as a delivery system for ferulic acid in corneal wound healing
Summary
The major difficulty in treating ocular diseases is to provide and maintain an optimal ocular concentration of the drug for a long period of time [1]. The high surface tension of an aqueous drop prevents spreading on the ocular surface Another disadvantage of the aqueous solutions is that since most of the chemical entities are lipophilic or high molecular weight compounds, their solubilization requires the addition of oils or surfactants that disturb the vision process and decrease the patient’s tolerability [5]. Topically-applied substances the cornea to aqueous humor, reaching melanin-containing tissues such as iris and the ciliary body. We highlight some chitosan-based drug delivery systems that proved to have good clinical efficacy and high potential for use in ophthalmology They are exemplified by recent studies exploring in-depth the techniques and mechanisms in order to improve ocular bioavailability of the active substances. Some research works are developed by exploiting the potential of chitosan in promoting corneal wound healing when used alone or in combination with other compounds with synergistic action
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