Cytochrome P450 reaction phenotyping of itraconazole hydroxylation in the dog

Matthew E. Tonero, Zhong Li, Jennifer M. Reinhart

Research output: Contribution to journalArticlepeer-review


Itraconazole (ITZ) is an important drug in the treatment of superficial and deep mycoses in dogs. Its primary metabolite is hydroxy-itraconazole, which has antifungal activity similar to the parent compound. The purpose of this study was to identify the cytochrome P450 enzyme (CYP) isoform(s) responsible for ITZ hydroxylation in canine liver. Reaction kinetics for ITZ hydroxylation were determined in a panel of canine recombinant CYPs and dog liver microsomes (DLMs). Findings were confirmed using CYP isoform-specific inhibitors in rCYPs and DLMs. In rCYP experiments, CYP2D15 and CYP3A12 had highest activity for ITZ hydroxylation. In inhibitor experiments, quinidine and erythromycin inhibited ITZ hydroxylation in CYP2D15 and CYP3A12, respectively, in an isoform-specific manner. In DLMs, quinidine and erythromycin combined inhibited ITZ hydroxylation more than erythromycin alone but not quinidine alone. However, this may be related to inhibitor potency rather than the contribution of the individual CYP isoforms to the reaction. These findings support a role for CYP2D15 and CYP3A12 in ITZ biotransformation in canine liver.

Original languageEnglish (US)
Pages (from-to)255-264
Number of pages10
JournalJournal of Veterinary Pharmacology and Therapeutics
Issue number3
StatePublished - May 2022


  • CYP
  • azole antifungal
  • biotransformation
  • metabolism
  • veterinary

ASJC Scopus subject areas

  • Pharmacology
  • veterinary(all)


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