The corneal and aqueous humor steroid concentrations produced by topical application of a standard dose of tritiated 0.125% and 1.0% ophthalmic solutions of prednisolone sodium phosphate were determined. In the absence of the corneal epithelium, the 1.0% formulation achieved the highest total corneal and aqueous humor concentrations of any steroid measured in our laboratory to date. Despite its virtual insolubility in lipid media, the drug was also able to cross the lipophilic epithelial barrier in significant amounts. Increasing drug concentration (0.125% to 1.0%) produced at least a commensurate increase in corneal and aqueous humor bioavailability. The steroid concentration in the anterior segment of the eye, following administration of the commercially available preparation, was almost twice that produced by the same drug delivered in buffered normal saline, indicating the influence of the vehicle on corneal absorption and penetration.
Kupferman A, Leibowitz HM. Topically Applied Steroids in Corneal DiseaseVI. Kinetics of Prednisolone Sodium Phosphate. Arch Ophthalmol. 1974;92(4):331-334. doi:10.1001/archopht.1974.01010010341017