Plasma concentrations of diclazuril following oral administration of diclazuril and diclazuril sodium salt to cattle

Levent Dirikolu, Andreas Fritz Lehner, Thomas Tobin

Research output: Contribution to journalArticlepeer-review

1 Scopus citations


Diclazuril is a triazine-based antiprotozoal agent widely used in veterinary practice that may have clinical application in the treatment of bovine protozoal diseases. The present study reports on the bioavailability, pharmacokinetics, and metabolism of diclazuril and diclazuril sodium salt in cattle following administration of diclazuril suspended in water and by direct application of diclazuril sodium salt to the oral mucosa. Compared with diclazuril itself, the sodium salt formulation of diclazuril applied to the oral mucosa was rapidly and reliably absorbed. Plasma concentrations of diclazuril peaked at around 8 h after oral-mucosal administration of diclazuril sodium salt. On the contrary, application of diclazuril itself orally resulted in delayed and variable absorption. The mean bioavailability of diclazuril as pure powder was 42.5% relative to diclazuril sodium salt indicating approximately 2.5-fold increase in bioavailability of diclazuril as a sodium salt relative to diclazuril as a pure compound in cattle. The present study also reports finding of a previously unreported diclazuril metabolite at high concentrations in plasma especially after oral administration of diclazuril. Further studies, including synthesis and characterization of the novel described metabolite, are required to accurately determine aspects of the metabolism of diclazuril in cattle.

Original languageEnglish
Pages (from-to)392-401
Number of pages10
JournalJournal of Veterinary Pharmacology and Therapeutics
Issue number4
StatePublished - Jul 2022

Bibliographical note

Funding Information:
Supported by Saxony Farms, Versailles, KY.

Publisher Copyright:
© 2022 John Wiley & Sons Ltd.


  • apicomplexans
  • cattle
  • diclazuril
  • diclazuril sodium salt
  • triazine agents

ASJC Scopus subject areas

  • Pharmacology
  • Veterinary (all)


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