EXPERIMENTAL AND BASIC RESEARCH STUDIES
Pharmacokinetics of triamcinolone acetonide following intramuscular and intra-articular administration to exercised Thoroughbred horses
Article first published online: 9 APR 2013
© 2013 EVJ Ltd
Equine Veterinary Journal
Volume 45, Issue 6, pages 715–720, November 2013
How to Cite
Knych, H. K., Vidal, M. A., Casbeer, H. C. and McKemie, D. S. (2013), Pharmacokinetics of triamcinolone acetonide following intramuscular and intra-articular administration to exercised Thoroughbred horses. Equine Veterinary Journal, 45: 715–720. doi: 10.1111/evj.12059
- Issue published online: 14 OCT 2013
- Article first published online: 9 APR 2013
- Accepted manuscript online: 1 FEB 2013 07:02AM EST
- Manuscript Accepted: 27 JAN 2013
- Manuscript Received: 27 NOV 2012
- Racing Medication and Testing Consortium
- triamacinolone acetonide (TA);
- syonvial fluid
Reason for performing study
The use of triamcinolone acetonide (TA) in performance horses necessitates establishing appropriate withdrawal times prior to performance.
To describe the plasma pharmacokinetics of TA and time-related urine and synovial fluid concentrations following i.m. and intra-articular administration to exercised Thoroughbred horses.
Twelve racing fit adult Thoroughbred horses received a single i.m. administration of TA (0.1 mg/kg bwt). After an appropriate washout period, the same horses then received a single intra-articular TA administration (9 mg) into the right antebrachiocarpal joint. Blood, urine and synovial fluid samples were collected prior to, and at various times, up to 60 days post drug administration and analysed using liquid chromatography-mass spectrometry. Plasma data were analysed using noncompartmental analysis.
Maximum measured plasma TA concentrations were 0.996 ± 0.391 at 13.2 h and 1.27 ± 0.278 ng/ml at 6.5 h for i.m. and intra-articular administration, respectively. The plasma terminal elimination half-life was 11.4 ± 6.53 and 0.78 ± 1.00 days for i.m. and intra-articular administration, respectively. Following i.m. administration, TA was below the limit of detection (LOD) by Days 52 and 60 in plasma and urine, respectively. Following intra-articular administration TA was undetectable by Day 7 in plasma and Day 8 in urine. Triamcinolone acetonide was also undetectable in any of the joints sampled following i.m. administration and remained above the limit of quantitation (LOQ) for 21 days following intra-articular administration.
Conclusions and potential relevance
This study extends previous studies describing the pharmacokinetics of TA following i.m. and intra-articular administration to the horse and suggests that plasma and urine concentrations are not a good indicator of synovial fluid concentrations. Furthermore, results of this study supports an extended withdrawal time for TA given i.m.
The Summary is available in Chinese – see Supporting information.