Pharmacokinetics and safety of silibinin in horses

Am J Vet Res. 2013 Oct;74(10):1327-32. doi: 10.2460/ajvr.74.10.1327.


Objective: To determine the oral bioavailability, single and multidose pharmacokinetics, and safety of silibinin, a milk thistle derivative, in healthy horses.

Animals: 9 healthy horses.

Procedures: Horses were initially administered silibinin IV and silibinin phospholipid orally in feed and via nasogastric tube. Five horses then consumed increasing orally administered doses of silibinin phospholipid during 4 nonconsecutive weeks (0 mg/kg, 6.5 mg/kg, 13 mg/kg, and 26 mg/kg of body weight, twice daily for 7 days each week).

Results: Bioavailability of orally administered silibinin phospholipid was 0.6% PO in feed and 2.9% via nasogastric tube. During the multidose phase, silibinin had nonlinear pharmacokinetics. Despite this, silibinin did not accumulate when given twice daily for 7 days at the evaluated doses. Dose-limiting toxicosis was not observed.

Conclusions and clinical relevance: Silibinin phospholipid was safe, although poorly bio-available, in horses. Further study is indicated in horses with hepatic disease.

Publication types

  • Clinical Trial, Phase I
  • Clinical Trial, Phase II

MeSH terms

  • Administration, Oral
  • Analysis of Variance
  • Animals
  • Area Under Curve
  • Biological Availability
  • Chromatography, Liquid
  • Dose-Response Relationship, Drug
  • Horses / metabolism*
  • Intubation, Gastrointestinal / veterinary
  • Mass Spectrometry
  • Plant Extracts / administration & dosage
  • Plant Extracts / blood
  • Plant Extracts / pharmacokinetics*
  • Silybin
  • Silybum marianum / chemistry*
  • Silymarin / administration & dosage
  • Silymarin / blood
  • Silymarin / pharmacokinetics*


  • Plant Extracts
  • Silymarin
  • Silybin