Penetration of topical indomethacin into phakic and aphakic rabbit eyes

The penetration of indomethacin labeled with radioactive carbon (14C) into all ocular tissues and fluids was determined at various intervals in both phakic and aphakic rabbit eyes after either single or multiple (every 12 hours for three days) topical application (50 microL) regimens. More indomethacin was found in the vitreous of aphakic eyes compared with phakic eyes after single- or multiple-drop administration. Retinal and choroidal indomethacin concentrations were equal in both phakic and aphakic eyes after either drug regimen and are much greater than those of the vitreous. A pathway other than diffusion through the vitreous exists for the drug to reach these tissues. The concentration of indomethacin reaching the retina and choroid is not sufficient to inhibit prostaglandin formation locally. The concentrations of indomethacin are high enough to inhibit the biotransformation of prostaglandin precursor only in the anterior segment.