Loteprednol loaded nanoformulations for corneal delivery: Ex-vivo permeation study, ocular safety assessment and stability studies

Loteprednol etabonate (LE) is a topical corticosteroid that is used in inflammatory and allergic conditions of the eye. Nanoformulations including solid lipid nanoparticles (SLN), nanostructured lipid carriers (NLC), and nanoemulsion (NE) of LE were prepared for increasing its ocular bioavailability and minimizing the risk of side effects. Nanoformulations were prepared using hot emulsification and ultrasonication technique. The stabilities of the SLN, NLC, and NE were studied at different thermal conditions for 180 days. In this context, alterations in particle size (PS), zeta potential (ZP), viscosity, pH, %EE, and thermal behavior of the formulations were determined. Ex vivo corneal permeation study was performed, subsequently, the tape stripping approach was conducted for defining the LE amount that was blocked by the tear film layer. In addition, to determine the LE amount in epithelial tissue, a homogenization test was performed. the PS of the formulations was between 82.23 and 126.9 nm, and ZPs were between −20.8 mV and −24.6 mV. Furthermore, SLN, NLC, and NE formulations were found to be 2.05, 1.86, and 1.39 times higher LE retained in the cornea against the marketed product, respectively. SLN, NLC, and NE might be alternative delivery systems by reducing the amount of LE for each dose and being used safely based on the results both of MTT and histopathological examinations as well.