Chitosan: A Good Candidate for Sustained Release Ocular Drug Delivery Systems

Abstract

This chapter focuses on the eye, one of the most important organs of humans. Current data on pathophysiology of the human eye are presented in direct correlation with a range of therapeutic products, with a well-known and widely used material, namely chitosan. Applications of chitosan biopolymer are described in the development of innovative, modern, therapeutic devices and solutions. Thus, chitosan is a good excipient either for classic drop-type ocular systems, as well as for complex drug systems such as nanostructures (nanoparticles, nanomicelles and nanosuspensions), liposomes, microemulsions, microspheres, in situ hydrogels and inserts or implants. A number of disadvantages for ocular administration of the drugs are thus overcome.

Advancement on Sustained Antiviral Ocular Drug Delivery for Herpes Simplex Virus Keratitis: Recent Update on Potential Investigation

“…An ocular minitablet is another useful solid dosage drug carrier for the ocular route of administration. It has a diameter of 2 to 4 mm and is inserted into the conjunctival sac of the eye [ 100 ]. Ocular minitablets also exist in in situ formulations.…”

“…After the minitablets undergo phase transition into a gel phase, the residence time for the formulation on the infection site increases [ 101 ]. As a result, the dosing frequency is decreased and this improves the compliance, especially of elderly and forgetful patients and patients with a busy working schedule [ 100 ]. Moreover, the local bioavailability of the therapeutic agents improves as it is slowly removed by body defense mechanisms [ 101 ].…”

Versatile Use of Chitosan and Hyaluronan in Medicine

“…They can be used as coagulating and flocculating agents for polluted wastewaters, in heavy metal or metalloid adsorption, e.g., Cu(II), Cd(II), Pb(II), Fe(III), Zn(II), and Cr(III), for the removal of dyes from industrial wastewater, e.g., from textile wastewaters, as well as for the removal of other organic pollutants such as organochloride pesticides, organic oxidized compounds, or fatty and oil impurities [ 13 ]. Chitosan can also participate in ruminants’ fermentation process [ 13 , 16 ]. Chitosan, due to its positive charge, efficiently binds negatively charged molecules, including fatty acids, lipids, and bile acids, properly excreting these molecules from the body.…”

“…Chitosan oligosaccharides, which usually have a degree of deacetylation less than approx. 50% and an average molar mass less than 10,000 Da, are very water soluble, resulting in solutions of low viscosity; due to these characteristics, chitosan oligosaccharides are favorably applied in biomedicine, contrary to high-molar-mass chitosan [ 10 , 16 , 19 ]. Chitosan and chitosan oligosaccharides can be used to attenuate metabolic syndrome by altering the microbiota in the gut, decreasing the risks of cardiovascular disease, and reducing inflammation in the intestinal mucosa [ 20 ].…”

“…Chitosan has excellent ocular tolerance. Ophthalmic formulations based on chitosan are easy to manufacture and exhibited an excellent tolerance when topically administered onto the cornea, since chitosan solutions have shown pseudoplastic and viscoelastic properties [ 16 , 42 ]. Most of the reports on the topical ocular administration of chitosan solutions refer to concentrations in the range of 0.5–5% and a molar mass higher than 70–100 kDa.…”