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The intramuscular bioavailability of a phenylbutazone preparation in the horse
Author(s) -
LANDUYT J.,
DELBEKE F. T.,
DEBACKERE M.
Publication year - 1993
Publication title -
journal of veterinary pharmacology and therapeutics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.527
H-Index - 60
eISSN - 1365-2885
pISSN - 0140-7783
DOI - 10.1111/j.1365-2885.1993.tb00216.x
Subject(s) - phenylbutazone , bioavailability , oxyphenbutazone , chemistry , horse , pharmacology , pharmacokinetics , plasma concentration , medicine , biology , paleontology
Landuyt, J., Delbeke, F.T. & Debackere, M. The intramuscular bioavailability of a phenylbutazone preparation in the horse.J vet. Pharmacol. Therap. 16, 494– 500. The plasma concentrations of phenylbutazone (PBZ) and its major metabolites, oxyphenbutazone (OPBZ) and γ‐OH‐phenylbutazone (OHPBZ) were determined for up to 72 h in six horses, following intravenous (i.v.) and intramuscular (i.m.) administration of 4 g phenylbutazone, 20 ml Phenylarthrite ® Ventoquinol (Vetoquinol Specialites Pharmaceutiques Veterinaires, Magny‐Vernois, 70200 Lure, France). After i.v. dosing the plasma disposition was best described by a two‐compartment open model. The hydroxylated metabolites OPBZ and OHPBZ were present in detectable concentrations for 72 h and 48 h, respectively. After 36 h the OPBZ concentrations exceeded plasma PBZ concentrations. The plasma disposition following i.m. injection could be described by a one‐compartment open model. The hydroxylated metabolites OPBZ and OHPBZ were present in detectable concentrations for 72 h and 36 h, respectively. Only after 72 h was the concentration of OPBZ in plasma higher than the concentration of PBZ. The mean i.m. bioavailability of phenylbutazone was calculated to be 91.7 ± 10.1%.