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The effect of age on phenylbutazone pharmacokinetics, metabolism and plasma protein binding in goats
Author(s) -
ELTOM S. E.,
GUARD C. L.,
SCHWARK W. S.
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.tb00158.x
Subject(s) - oxyphenbutazone , phenylbutazone , volume of distribution , pharmacokinetics , half life , medicine , plasma clearance , endocrinology , metabolism , adult male , plasma concentration , zoology , chemistry , biology
Phenylbutazone (PBZ) was administered intravenously as a single dose (10 mg/ kg) to adult male and 1‐day‐, 10‐day‐, 4‐week‐ and 6 week‐old male goats. The plasma concentration of PBZ and its major metabolites oxyphenbutazone (OPBZ) and γ‐hydroxyphenbutazone (γ‐OHPBZ) was measured over time. The elimination half‐life (t ½β ) of PBZ decreased from 120 h in the 1‐day‐old to 16 h in the adult goats. Although the volume of distribution ( V d ) did not change significantly during maturation, the total body clearance ( Cl B) increased from 2 ml.h ‐1 .kg ‐1 in I‐day‐old t o 13 ml.h ‐1 .kg ‐1 in the adult goats; the increase was 2‐fold in the first 10 days of life. Oxyphenbutazone was detectable in the plasma of adult and 6‐week‐old goats as early as 15 min after PBZ administration. Its peak concentration occurred at 1.5 h (1.6 μg/ml) in adults and at 6 h (0.95 μg/ml) and 12 h (0.36 μg/ml) in 6‐ and 4‐week‐old goats respectively. The highest plasma concentration of γ‐OHPBZ was achieved in 4‐week‐old followed by 6‐week‐old and adult animals.