Abstract

• The metabolism of drug and arachidonic acid(AA) by diabetic rat ocular tissues was studied. Little information is available on drug metabolism enzymes in ocular tissues. I investigated the presence of various cytochrome P-450 isoenzymes by measuring different drug metabolizing enzymes. i.e., 7-ethoxycoumarin-0-deethylase and benzphetamine demethylase activities in cornea and choroid, retina or sclera.
  This results demonstrate that choroid, retina or sclera possess the highest activities of drug metabolizing enzymes. The highest activities of 7-ethoxycoumarin-0-deethylase and benzphetamine demathylase were found in choroid, retina or sclera. The highest activities of drug metabolizing enzyrnes is accompanied by high activity of NADPH cytochrome P-45O(C) reductase, an integral component of this enzyme study. The choroid, retina or sclera possesses the high activity of metabolizing arachidonic acid to biologically active compounds, whereas the cornea has tow activity of metabolizing arachidonic acid. A form of cytochrome P-450 has appear rat ocular tissues in diabetes and the effect of diabetes on ocular tissues cytochrome P-450 expression can be reversed by insulin treatment.
  The specialized location of cytochrome P-450 isozymes in ocular tissues suggests a physiological function related to activation of endogenous compounds such as arachidonic acid, in addition to detoxifiaction of drugs. Thus, the choroid, retina or sclera is the site of metabolism and detoxification of drugs are carried to ocular tissues via circulating blood.