The cell culture medium was changed every 2–3 days. The cells were used for permeability assays after three weeks of culturing. 2.3. Permeability Assays 2.3.1. Permeability Assays of Formulations Containing Intranasal Corticosteroids with Low Aqueous Solubility (Beclomethasone Dipropionate, Fluticasone ...