Factors influencing the corneal permeability of prostaglandin F2α and its isopropyl ester in vitro

Abstract The corneal uptake and permeability of PGF 2α and PGF 2α isopropyl ester were determined in vitro with a perfusion apparatus using pig cornea. A de-epithelization of the cornea increased the permeability of PGF 2α , whereas the transport of PGF 2α isopropyl ester was decreased. Similar results were obtained in the presence of benzalkonium chloride (0.01%). PGF 2α isopropyl ester was hydrolyzed during its permeation and only PGF 2α was detected on the endothelial side. The hydrolysis occurred mainly in the epithelium. PGF 2α isopropyl ester was more stable to butyrylcholinesterase than PGF 2α methyl and benzyl ester. Incubation with cornea homogenate gave the same result. The cholinesterase inhibitor synstigmine methyl sulphate and benzalkonium chloride reduced the hydrolytic activity of the cornea homogenate. Leucine aminopeptidase and alkaline phosphatase activities were observed in the homogenate. These enzymes had no effect on the esters.