The effect of inflammation on the disposition of phenylbutazone in Thoroughbred horses

Mills, P. C., Ng, J. C. and Auer, D. E. (1996) The effect of inflammation on the disposition of phenylbutazone in Thoroughbred horses. Journal of Veterinary Pharmacology and Therapeutics, 19 6: 475-481. doi:10.1111/j.1365-2885.1996.tb00085.x

Author Mills, P. C.
Ng, J. C.
Auer, D. E.
Title The effect of inflammation on the disposition of phenylbutazone in Thoroughbred horses
Journal name Journal of Veterinary Pharmacology and Therapeutics   Check publisher's open access policy
ISSN 0140-7783
Publication date 1996-12-01
Year available 1996
Sub-type Article (original research)
DOI 10.1111/j.1365-2885.1996.tb00085.x
Open Access Status Not Open Access
Volume 19
Issue 6
Start page 475
End page 481
Total pages 7
Place of publication Oxford, United Kingdom
Publisher Wiley-Blackwell Publishing
Language eng
Formatted abstract
The effect of inflammation on the disposition of phenylbutazone (PBZ) was investigated in Thoroughbred horses. An initial study (n= 5) in which PBZ (8.8 mg/kg) was injected intravenously twice, 5 weeks apart, suggested that the administration of PBZ would not affect the plasma kinetics of a subsequent dose. Two other groups of horses were given PBZ at either 8.8 mg/kg (n= 5) or 4.4 mg/kg (n= 4). Soft tissue inflammation was then induced by the injection of Freud's adjuvant and the administration of PBZ was repeated at a dose level equivalent to, but five weeks later than, the initial dose. Inflammation did not appear to affect the plasma kinetics or the urinary excretion of PBZ and its metabolites, oxyphenbutazone (OPBZ) or hydroxyphenylbutazone (OHPBZ) when PBZ was administered at 8.8 mg/kg. However, small but significant increases (P<0.05) in total body clearance (CLB; 29.2 ± 3.9 vs. 43.8 ± 8.1 mL/ h-kg) and the volume of distribution, calculated by area (Vd(area); 0.18 ± 0.05 vs. 0.25 ± 0.03 L/kg) or at steady-state (Vd(SS); 0.17±0.04 vs. 0.25 ± 0.03 L/ kg), were obtained in horses after adjuvant injection, compared to controls, when PBZ was administered at 4.4 mg/kg which corresponded to relatively higher tissues concentrations and lower plasma concentrations (calculated) at the time of maximum peripheral PBZ concentration. Soft tissue inflammation also induced a significantly (P<0.05) higher amount of OPBZ in the urine 18 h after PBZ administration but the total urinary excretion of analytes over 48 h was unchanged. These results have possible implications regarding the administration of PBZ to the horse close to race-day.
Keyword Pharmacology & Pharmacy
Veterinary Sciences
Pharmacology & Pharmacy
Veterinary Sciences
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collection: National Research Centre for Environmental Toxicology Publications
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Created: Wed, 09 Feb 2011, 20:50:50 EST