Pharmacy World and Science

, Volume 19, Issue 6, pp 255–263 | Cite as

The role of non—P450 enzymes in drug oxidation.

  • Christine Beedham


In addition to cytochrome P450, oxidation of drugs and other xenobiotics can also be mediated by non–P450 enzymes, the most significant of which are flavin monooxygenase, monoamine oxidase, alcohol dehydrogenase, aldehyde dehydrogenase, aldehyde oxidase and xanthine oxidase. This article highlights the importance of these non–P450 enzymes in drug metabolism. A brief introduction to each of the non–P450 oxidizing enzymes is given in this review and the oxidative reactions have been illustrated with clinical examples. Drug oxidation catalyzed by enzymes such as flavin monooxygenase and monoamine oxidase may often produce the same metabolites as those generated by P450 and thus drug interactions may be difficult to predict without a clear knowledge of the underlying enzymology. In contrast, oxidation via aldehyde oxidase and xanthine oxidase gives different metabolites to those resulting from P450 hydroxylation. Although oxidation catalyzed by non-P450 enzymes can lead to drug inactivation, oxidation may be essential for the generation of active metabolite(s). The activation of a number of prodrugs by non–P450 enzymes is thus described. It is concluded that there is still much to learn about factors affecting the non–P450 enzymes in the clinical situation.

Drug oxidation Non–P450 enzymes Prodrug activation Flavin monooxygenase Monoamine oxidase Aldehyde dehydrogenase Aldehyde oxidase Xanthine oxidase 


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© Kluwer Academic Publishers 1997

Authors and Affiliations

  • Christine Beedham
    • 1
  1. 1.Pharmaceutical ChemistrySchool of Pharmacy, University of Bradford, BradfordWest YorkshireUK

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