2.5.10. Ex Vivo Corneal Permeation Study

The ex vivo corneal penetration or permeation investigation was executed on eradicated goat cornea acquired from the local slaughterhouse. The goat cornea was collected and stored in the cold saline medium (0.9% w/v sodium chloride solution at 4 °C) until it was used. The goat eyes were rinsed in cold brine to remove the sticking or extra tissue. The cornea was carefully extracted from the eyeball with 2–4 mm of sclera tissue surrounding it, and this excised cornea (surface area 1.13 cm²) was fixed between the acceptor and donor compartment of the Franz diffusion cell apparatus (Orchid Scientific Pvt. Ltd., Nashik, India) with the acceptor compartment filled with 25 mL of STF. About 1 mL of VCZ-MA-NPs and VCZ-MP-NPs was placed on the cornea through the donor compartment. This assembly was set at 37± 0.5 °C with 100 rpm. Aliquants of both formulations were collected at predefined time intervals and analyzed using HPLC at 256 nm. The permeation studies were performed in triplicates for both mucoadhesive (MA-NPs) and mucous penetrating nanoparticles (MP-NPs) and reported the data as mean± SD [41].

Permeability flux was calculated using the following formula:

where A is the area for permeation (cm²), Q_A is the amount of drug permeated through the cornea (mg), Js is the drug flux (mg/cm²/h), and t is the exposure duration (h). Additionally, permeability (P) was determined using the equation:

where C_d denotes to total drug amount loaded into the donor compartment (mg).