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Pharmacokinetics and bioequivalence of two suxibuzone oral dosage forms in horses
Author(s) -
Jaraiz,
; Rodriguez,
M. I. San Andrés,
Marcos González
Publication year - 1999
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 - 10.1046/j.1365-2885.1999.00219.x
Subject(s) - bioequivalence , oxyphenbutazone , phenylbutazone , cmax , pharmacokinetics , chemistry , chromatography , plasma concentration , oral administration , pharmacology , dosage form , medicine
A disposition and bioequivalence study with a suxibuzone granulated and a suxibuzone paste oral formulation was performed in horses. Suxibuzone (SBZ) is a nonsteroidal anti‐inflammatory drug, which was administered to horses ( n = 6) at a dosage of 19 mg/kg bwt by the oral route (p.o.) in a two period cross‐over design. Suxibuzone is very rapidly transformed into its main active metabolites, phenylbutazone (PBZ) and oxyphenbutazone (OPBZ). Therefore plasma and synovial fluid concentrations of SBZ, PBZ and OPBZ were simultaneously measured by a sensitive and specific high‐performance liquid chromatographic method. The pharmacokinetic parameters were determined by noncompartmental analysis. Suxibuzone could not be detected in any plasma and synovial fluid samples (< 0.04 μg/mL). Plasma PBZ and OPBZ concentrations were detected between 30 min and 72 h after granulate and paste administration. Mean plasma concentration of PBZ peaked at 5 h (34.5 ± 6.7 μg/mL) and at 7 h (38.8 ± 8.4 μg/mL), and mean area under the concentration–time curve ( AUC 0→LOQ ) was 608.0 ± 162.2 μg·h/mL and 656.6 ± 149.7 μg·h/mL after granulate and paste administration, respectively. Mean plasma concentration of OPBZ increased to 5–6.7 μg/mL, with the maximum concentration ( C max ) appearing between 9 and 12 h after administration of both formulations. The AUC s 0→LOQ for OPBZ were also similar (141.8 ± 48.3 μg·h/mL granulate vs. 171.4 ± 45.0 μg·h/mL paste). It was concluded that the suxibuzone products were bioequivalent with respect to PBZ. For OPBZ, the 95% confidence intervals of the pharmacokinetic parameters were within the acceptable range of 80–125%. The paste formulation provided greater bioavailability of PBZ and OPBZ.