Abstract
Cocaine abuse and toxicity remain widespread problems in the United States. Currently cocaine toxicity is treated only symptomatically, as there is no FDA-approved pharmacotherapy to directly treat cocaine toxicity. To address this unmet need, a stabilized mutant of bacterial cocaine esterase (DM-CocE), which hydrolyzes cocaine into physiologically inactive metabolites and has low immunogenic potential, has been developed and previously tested in rodent and non-human primate models of cocaine toxicity. Here we document the rapid cocaine hydrolysis by low doses of DM-CocE in vitro and in vivo, as well as the pharmacokinetics and distribution of the DM-CocE protein in rats. DM-CocE at 50.5 μg/kg effectively eliminated 4 mg/kg cocaine within 2 minutes in both male and female rats as measured by mass spectrometry. We expanded on these findings by using a pharmacologically 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 30-60 minutes in both species. The rapid elimination of DM-CocE was quantified using [35S] labeling of the enzyme. DM-CocE is eliminated with a half-life of 2.1 hours from Sprague Dawley rats. Minor urinary output of full length and fragmented DM-CocE is also observed. Immunohistochemistry, western blotting and radiography were all 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 for a toxicity therapeutic and should reduce the likelihood of immunogenic or adverse reactions as DM-CocE moves towards clinical use.
- Received August 5, 2011.
- Revision received September 28, 2011.
- Accepted October 6, 2011.
- The American Society for Pharmacology and Experimental Therapeutics