Chitosan modulated niosomes for improved ocular delivery of brinzolamide

Brinzolamide (BZ) is considered a promising pharmaceutical agent for lowering elevated intraocular pressure (IOP). However, its poor aqueous solubility limits its ocular bioavailability. Niosomes showed promising potential in ophthalmic delivery. Chitosan coating may extend the benefits of niosomes by imparting mucoadhesive potential. The aim of this investigation was to explore the potential of chitosan-coated niosomes (CS-niosomes) for improving the ocular delivery of BZ. Standard niosomes composed of Span 60, cholesterol, and ursodeoxycholic acid were loaded with BZ. The same system was coated with chitosan to provide CS-niosomes. Niosomes morphology, size, BZ entrapment efficiency and release were determined. The IOP-lowering effect of BZ-loaded niosomes was monitored after ocular administration in rabbits with experimentally induced glaucoma using lab-prepared suspension and marketed eye drops (Azopt®) as control. Standard niosomes and CS-niosomes were spherical vesicles having size of 193.50 and 159.90 nm, respectively. BZ was entrapped with efficiency of 90.02% and 88.43% in both systems, respectively, with no significant difference observed in their release behaviour. With respect to IOP-lowering ability, CS-niosomes > standard niosomes > Azopt® > lab-prepared suspension with CS-niosomes preserving the efficacy even after 10 hours. This study demonstrated the potential of CS-niosomes as a promising nanocarrier for enhanced ocular delivery of BZ.