Document Detail


The use of 18O-exchange and base-catalyzed N-dealkylation with liquid chromatography/tandem mass spectrometry to identify carbinolamide metabolites.
MedLine Citation:
PMID:  20552706     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Oxidation of N-alkyl-substituted amides is a common transformation observed in metabolism studies of drugs and other chemicals. Metabolism at the alpha carbon atom can produce stable carbinolamide compounds, which may be abundant enough to require complete confidence in structural assignments. In a drug discovery setting, rapid structural elucidation of test compounds is critical to inform the compound selection process. Traditional approaches to the analysis of carbinolamides have relied upon the time-consuming synthesis of authentic standards or purification of large enough quantities for characterization by nuclear magnetic resonance (NMR). We describe a simple technique used in conjunction with liquid chromatography/tandem mass spectrometry (LC/MS/MS) which demonstrates the chemical identity of a carbinolamide by its distinctive ability to reversibly exchange [(18)O]water through an imine intermediate. A key advantage of the technique is that the chromatographic retention times of metabolites are preserved, allowing direct comparisons of mass chromatograms from non-treated and [(18)O]water-treated samples. Metabolites susceptible to the treatment are clearly indicated by the addition of 2 mass units to their original mass. An additional test which can be used in conjunction with (18)O-exchange is base-catalyzed N-dealkylation of N-(alpha-hydroxy)alkyl compounds. The use of the technique is described for carbinolamide metabolites of dirlotapide, loperamide, and a proprietary compound.
Authors:
Andrew J Bessire; Alfin D N Vaz; Gregory S Walker; Wei Wei Wang; Raman Sharma
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Publication Detail:
Type:  Evaluation Studies; Journal Article    
Journal Detail:
Title:  Rapid communications in mass spectrometry : RCM     Volume:  24     ISSN:  1097-0231     ISO Abbreviation:  Rapid Commun. Mass Spectrom.     Publication Date:  2010 Jul 
Date Detail:
Created Date:  2010-06-22     Completed Date:  2010-09-20     Revised Date:  2010-10-01    
Medline Journal Info:
Nlm Unique ID:  8802365     Medline TA:  Rapid Commun Mass Spectrom     Country:  England    
Other Details:
Languages:  eng     Pagination:  2151-61     Citation Subset:  IM    
Copyright Information:
Copyright 2010 John Wiley & Sons, Ltd.
Affiliation:
Department of Pharmacokinetics, Dynamics, and Metabolism, Pfizer Global R&D, Groton, CT 06340, USA. andrew.j.bessire@pfizer.com
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MeSH Terms
Descriptor/Qualifier:
Animals
Carbamates / administration & dosage,  chemistry*,  metabolism*
Catalysis
Chromatography, Liquid / methods*
Dealkylation
Female
Indoles / administration & dosage,  chemistry*,  metabolism*
Male
Molecular Structure
Oxygen Isotopes / analysis*
Rats
Rats, Sprague-Dawley
Tandem Mass Spectrometry / methods*
Chemical
Reg. No./Substance:
0/5-((4'-trifluoromethyl-biphenyl-2-carbonyl)-amino)-1H-indole-2-carboxylic acid benzylmethyl carbamoylamide; 0/Carbamates; 0/Indoles; 0/Oxygen Isotopes

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