Involvement of CYP2D6, CYP3A4, and other cytochrome P-450 isozymes in N-dealkylation reactions

J Pharmacol Toxicol Methods. 1994 Aug;31(4):177-86. doi: 10.1016/1056-8719(94)90001-9.


Metabolic N-dealkylation is a commonly observed biotransformation with tertiary and secondary amine drugs and related N-alkylated amides, but surprisingly little is known about the cytochrome P-450 isozymes involved in these dealkylation reactions. In this review, evidence is provided that supports the involvement of various P-450 isozymes, but especially CYP3A4 and other isozymes of the CYP3A subfamily. Although CYP2D6 is generally not considered to be capable of catalyzing the N-dealkylation of basic drugs, some examples of the involvement of this important isozyme in N-dealkylation reactions are identified. Procedures used to identify individual P-450 isozymes involved in N-dealkylation reactions are discussed.

Publication types

  • Review

MeSH terms

  • Amitriptyline / metabolism
  • Animals
  • Citalopram / metabolism
  • Cytochrome P-450 CYP2D6
  • Cytochrome P-450 CYP3A
  • Cytochrome P-450 Enzyme System / physiology*
  • Dealkylation
  • Humans
  • Imipramine / metabolism
  • Isoenzymes / physiology*
  • Mixed Function Oxygenases / physiology*


  • Isoenzymes
  • Citalopram
  • Amitriptyline
  • Cytochrome P-450 Enzyme System
  • Mixed Function Oxygenases
  • CYP3A protein, human
  • Cytochrome P-450 CYP2D6
  • Cytochrome P-450 CYP3A
  • CYP3A4 protein, human
  • Imipramine