Identification of human liver cytochrome P450 enzymes involved in the metabolism of SCH 351125, a CCR5 antagonist

Xenobiotica. 2005 May;35(5):405-17. doi: 10.1080/00498250500136569.


The identification and relative contribution of human cytochrome P450 enzyme(s) involved in the metabolism of SCH 351125 were investigated. In human liver microsomes, O-deethylation was the major metabolic pathway, whereas aromatization of a piperidine ring to pyridine and the reduction of the N-oxide moiety were minor routes. Recombinant human CYP3A4 and CYP2C9 both exhibited catalytic activity with respect to the formation of rotameric O-deethylated metabolites (M12, M13), the metabolites resulting from aromatization (M22/M24) and N-oxide reduction (M31). Using the relative activity factor (RAF) approach, the relative contributions of CYP3A4 and CYP2C9 to M13 formation were estimated to be 76 and 24%, respectively. There was a high correlation (r>0.96) between the rate of formation of M12 and M13 and 6 beta-hydroxylation of testosterone catalysed by CYP3A4/5. Ketoconazole (2microM) and CYP3A4/5-specific inhibitory monoclonal antibody inhibited the formation of M12 and M13 from human liver microsomes by approximately 60 and 71%, respectively. The results demonstrate that the in vitro metabolism of SCH 351125 is mediated primarily via CYP3A4 and that CYP2C9 plays a minor role. Clinical study designs should encompass these enzymology data to address any potential drug interactions.

MeSH terms

  • Biotransformation
  • CCR5 Receptor Antagonists*
  • Cyclic N-Oxides / pharmacology*
  • Cytochrome P-450 CYP3A
  • Cytochrome P-450 Enzyme System / metabolism*
  • Humans
  • Kinetics
  • Microsomes, Liver / enzymology*
  • Oximes
  • Piperidines / pharmacology*
  • Pyridines / pharmacology*
  • Recombinant Proteins / metabolism


  • CCR5 Receptor Antagonists
  • Cyclic N-Oxides
  • Oximes
  • Piperidines
  • Pyridines
  • Recombinant Proteins
  • Ancriviroc
  • Cytochrome P-450 Enzyme System
  • CYP3A protein, human
  • Cytochrome P-450 CYP3A
  • CYP3A4 protein, human