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Effects of oral cimetidine on plasma concentrations of phenylbutazone in horses
Author(s) -
CHRISTENSEN J. M.,
BLYTHE L. L.,
CRAIG A. M.
Publication year - 1985
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.1365-2885.1985.tb00974.x
Subject(s) - phenylbutazone , cimetidine , oxyphenbutazone , metabolite , chemistry , pharmacology , pharmacokinetics , plasma concentration , medicine , biochemistry
Phenylbutazone was administered to six Thoroughbred horses in a cross‐over study in which die horses received cimetidine pretreatment or no cimetidine pretreatment. Blood samples were collected at various times for 48 h after phenylbutazone administration and the plasma was analysed for phenylbutazone. Cimetidine pretreatment elevated phenylbutazone plasma concentrations during the first 8 h after phenylbutazone administration. The absorption rate, maximum phenylbutazone plasma concentrations and AUC were significantly greater with cimetidine pretreatment. The half‐life of phenylbutazone did not change with cimetidine pretreatment; however, lower plasma concentrations of the metabolite gamma‐hydroxyphenylbutazone were observed with cimetidine pretreatments. Plasma concentrations of the metabolite oxyphenbutazone were unchanged with cimetidine pretreatment compared to control values. Twenty‐four‐hour plasma concentrations of phenylbutazone were not different from control values with cimetidine pretreatment. This study suggests that concurrent treatment with cimetidine and phenylbutazone 24 h before race time does not result in elevations of plasma phenylbutazone concentrations above control values.