Pc. Mills et al., DISPOSITION AND URINARY-EXCRETION OF PHENYLBUTAZONE IN NORMAL AND FEBRILE GREYHOUNDS, Research in Veterinary Science, 59(3), 1995, pp. 261-266
Five days after the induction of acute systemic inflammation in greyho
unds by intramuscular and subcutaneous injections of Freund's adjuvant
, the hepatic concentrations of cytochromes P-450 and b(5), the activi
ties of the hepatic microsomal enzymes aniline p-hydroxylase and amino
pyrine n-demethylase and the disposition and urinary excretion of phen
ylbutazone were determined. The mean plasma concentrations of phenylbu
tazone after intravenous administration were described by the bi-expon
ential equations: Cp = 144.2e(-34.6t) + 171.5e(-0.104t) for five norma
l greyhounds and Cp = 113.6e(-16.13t) + 163.1e(-0.108t) for five febri
le greyhounds. The elimination half-lives, total body clearances and a
pparent volumes of distribution were 6.7 hours, 18.4 ml kg(-1) hour(-1
) and 0.18 litre kg(-1), for the normal greyhounds, and 6.4 hours, 19.
5 ml kg(-1) hour(-1) and 0.18 litre kg(-1) for the febrile greyhounds.
There were no significant differences between the pharmacokinetic par
ameters describing the distribution and elimination of phenylbutazone,
or between the quantities of phenylbutazone, oxyphenbutazone and hydr
oxyphenylbutazone excreted in the urine. In the febrile greyhounds, th
ere were significant decreases in the hepatic microsomal concentration
s of cytochromes P-450 and bg and in the activities of aniline p-hydro
xylase and aminopyrine n-demethylase.