Evaluation of the hydrolytic activity of a long-acting mutant bacterial cocaine in the presence of commonly co-administered drugs

Accelerating cocaine metabolism as an approach to the treatment of cocaine abuse and toxicity

One pharmacokinetic approach to the treatment of cocaine abuse and toxicity involves the development of compounds that can be safely administered to humans and that accelerate the metabolism of cocaine to inactive components. Catalytic antibodies have been developed and shown to accelerate cocaine metabolism, but their catalytic efficiency for cocaine is relatively low. Mutations of human butyrylcholinesterase and a bacterial cocaine esterase found in the soil of coca plants have also been developed. These compounds accelerate cocaine metabolism and antagonize the behavioral and toxic effects of cocaine in animal models. Of these two approaches, the human butyrylcholinesterase mutants show the most immediate promise as they would not be expected to evoke an immune response in humans.

Bacterial cocaine esterase: a protein-based therapy for cocaine overdose and addiction

Cocaine is highly addictive and there are no pharmacotherapeutic drugs available to treat acute cocaine toxicity or chronic abuse. Antagonizing an inhibitor such as cocaine using a small molecule has proven difficult. The alternative approach is to modify cocaine's pharmacokinetic properties by sequestering or hydrolyzing it in serum and limiting access to its sites of action. We took advantage of a bacterial esterase (CocE) that has evolved to hydrolyze cocaine and have developed it as a therapeutic that rapidly and specifically clears cocaine from the subject. Native enzyme was unstable at 37°C, thus limiting CocE's potential. Innovative computational methods based on the protein's structure helped elucidate its mechanism of destabilization. Novel protein engineering methodologies were applied to substantially improve its stability in vitro and in vivo. These improvements rendered CocE as a powerful and efficacious therapeutic to treat cocaine intoxication and lead the way towards developing a therapy for addiction.

Repeated administration of a mutant cocaine esterase: effects on plasma cocaine levels, cocaine-induced cardiovascular activity, and immune responses in rhesus monkeys

Previous studies have demonstrated the capacity of a long-acting mutant form of a naturally occurring bacterial double mutant cocaine esterase (DM CocE) to antagonize the reinforcing, discriminative, convulsant, and lethal effects of cocaine in rodents and reverse the increases in mean arterial pressure (MAP) and heart rate (HR) produced by cocaine in rhesus monkeys. This study was aimed at characterizing the immunologic responses to repeated dosing with DM CocE and determining whether the development of anti-CocE antibodies altered the capacity of DM CocE to reduce plasma cocaine levels and ameliorate the cardiovascular effects of cocaine in rhesus monkeys. Under control conditions, intravenous administration of cocaine (3 mg/kg) resulted in a rapid increase in the plasma concentration of cocaine (n = 2) and long-lasting increases in MAP and HR (n = 3). Administration of DM CocE (0.32 mg/kg i.v.) 10 min after cocaine resulted in a rapid hydrolysis of cocaine with plasma levels below detection limits within 5 to 8 min. Elevations in MAP and HR were significantly reduced within 25 and 50 min of DM CocE administration, respectively. Although slight (10-fold) increases in anti-CocE antibodies were observed after the fourth administration of DM CocE, these antibodies did not alter the capacity of DM CocE to reduce plasma cocaine levels or ameliorate cocaine's cardiovascular effects. Anti-CocE titers were transient and generally dissipated within 8 weeks. Together, these results suggest that highly efficient cocaine esterases, such as DM CocE, may provide a novel and effective therapeutic for the treatment of acute cocaine intoxication in humans.

Long-lasting effects of a PEGylated mutant cocaine esterase (CocE) on the reinforcing and discriminative stimulus effects of cocaine in rats

Recent mutagenesis studies have identified a mutant G4C/S10C/T172R/G173Q cocaine esterase (CCRQ CocE) with an in vitro duration of action of >40 days. Although the in vivo duration of CCRQ CocE's action was <24 h, modification of this enzyme with polyethylene glycol (PEG) polymers resulted in a CocE (PEG-CCRQ CocE) capable of preventing cocaine-induced lethality for up to 72 h. The current studies were aimed at providing a detailed characterization of the effectiveness, selectivity, and duration of PEG-CCRQ CocE's actions in cocaine self-administration and discrimination assays in rats. Pretreatment with PEG-CCRQ CocE produced dose-dependent rightward shifts in the dose-response curves for cocaine self-administration and discrimination, with the highest dose of PEG-CCRQ CocE capable of producing an initial shift of cocaine's reinforcing and interoceptive effects of >30-fold to the right, with significant inhibition of these effects observed for up to 72 h. Although PEG-CCRQ CocE also produced slight reductions in the rates of methylphenidate- and food-reinforced responding, these effects were short-lived, lasting <24 h. Finally, when taken together with the finding that PEG-CCRQ CocE failed to alter the cocaine-like interoceptive effects of either methylphenidate or d-amphetamine, these results suggest that PEG-CCRQ CocE possesses a high degree of pharmacologic specificity for cocaine and a prolonged in vivo duration of action. In conclusion, these studies provide strong evidence to support the further development of long-lasting, highly efficient CocEs, such as PEG-CCRQ CocE, as a potential therapeutic option for the treatment of cocaine abuse in humans.