title: Evaluation of the hydrolytic activity of a long-acting mutant bacterial cocaine in the presence of commonly co-administered drugs.
abstract: BACKGROUND
  Cocaine toxicity is a prevalent problem in the Unites States for which there is currently no FDA-approved pharmacotherapy. We have developed a bacterial cocaine esterase (CocE) towards this indication. A thermostabilized mutant of CocE (DM-CocE) retains the hydrolytic activity of the wild-type esterase, rapidly hydrolyzing cocaine into the inactive metabolites ecgonine methyl ester and benzoic acid, and can prevent cocaine toxicities in rodent and non-human primate models. To advance DM-CocE towards clinical use, we examine here how the hydrolytic activity of DM-CocE is altered by some drugs commonly co-administered with cocaine.
  
  
  METHODS
  We employed a spectrophotometric cocaine hydrolysis assay to evaluate whether pharmacologically relevant doses of alcohol, nicotine, morphine, phencyclidine, ketamine, methamphetamine, naltrexone, naloxone, or midazolam would alter the Michaelis-Menten kinetics of DM-CocE for cocaine. Mass spectrometry was used to evaluate interaction with diazepam as this drug interferes with the absorbance spectra of cocaine critical for the spectrophotometric assay.
  
  
  RESULTS
  Alcohol, nicotine, morphine, phencyclidine, ketamine, methamphetamine, naltrexone, naloxone, and midazolam did not alter cocaine hydrolysis by DM-CocE. However, diazepam significantly slowed DM-CocE cocaine hydrolysis at very high concentrations, most likely through interaction of the phenyl ring of the benzodiazepine with the active site of DM-CocE.
  
  
  CONCLUSIONS
  DM-CocE does not display significant drug interactions, with the exception of diazepam, which may warrant further study as DM-CocE progresses towards a clinically used pharmacotherapy for cocaine toxicity. Alternate benzodiazepines, e.g., midazolam could be used to avoid this potential interaction.
authors.affiliation: University of Michigan, Department of Pharmacology, USA.
authors.forename: Remy L
authors.initials: RL
authors.lastname: Brim
authors.forename: Kathleen R
authors.initials: KR
authors.lastname: Noon
authors.forename: Joseph
authors.initials: J
authors.lastname: Nichols
authors.forename: Diwahar
authors.initials: D
authors.lastname: Narasimhan
authors.forename: James H
authors.initials: JH
authors.lastname: Woods
authors.forename: Roger K
authors.initials: RK
authors.lastname: Sunahara
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism*; D002265:Carboxylic Ester Hydrolases / Q000378:metabolism*; D003042:Cocaine / Q000032:analysis / Q000378:metabolism*; D003975:Diazepam / Q000032:analysis / Q000378:metabolism; D004353:Drug Evaluation, Preclinical; D004347:Drug Interactions / Q000502:physiology; D006868:Hydrolysis; D013058:Mass Spectrometry / Q000379:methods; D009154:Mutation / Q000502:physiology*; D004364:Pharmaceutical Preparations / Q000032:analysis / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D004364:Pharmaceutical Preparations; D002265:Carboxylic Ester Hydrolases; C019921:cocaine esterase; D003042:Cocaine; D003975:Diazepam