The Fate of Bacterial Cocaine Esterase (CocE): An In Vivo Study of CocE-Mediated Cocaine Hydrolysis, CocE

Cocaine abuse and toxicity remain widespread problems in the United States. Currently cocaine toxicity is treated only symptom-atically, because there is no Food and Drug Administration-approved pharmacotherapy for this indication. To address the unmet need, a stabilized mutant of bacterial cocaine esterase [T172R/G173Q-CocE (DM-CocE)], which hydrolyzes cocaine into inactive metabolites and has low immunogenic potential, has been developed and previously tested in animal models of co-caine toxicity. Here, we document the rapid cocaine hydrolysis by low doses of DM-CocE in vitro and in vivo, as well as the phar-macokinetics and distribution of the DM-CocE protein in rats. DM-CocE at 50.5 g/kg effectively eliminated 4 mg/kg cocaine within 2 min in both male and female rats as measured by mass spectrometry. We expanded on these findings by using a phar-macologically relevant dose of DM-CocE (0.32 mg/kg) in rats and monkeys to hydrolyze convulsant doses of cocaine. DM-CocE reduced cocaine to below detection limits rapidly after injection; however, elimination of DM-CocE resulted in peripheral cocaine redistribution by 30 to 60 min. Elimination of DM-CocE was quan-tified by using [35S] labeling of the enzyme and was found to have a half-life of 2.1 h in rats. Minor urinary output of DM-CocE was also observed. Immunohistochemistry, Western blotting, and ra-diography all were used to elucidate the mechanism of DM-CocE elimination, rapid proteolysis, and recycling of amino acids into all tissues. This rapid elimination of DM-CocE is a desirable property of a therapeutic for cocaine toxicity and should reduce the likelihood of immunogenic or adverse reactions as DM-CocE moves toward clinical use