EFFECT OF PROBENECID ON THE PHARMACOKINETICS OF FLUNIXIN MEGLUMINE AND PHENYLBUTAZONE IN HEALTHY MARES

Pharmacokinetic values for flunixin meglumine (1 mg/kg of body weight) and phenylbutazone (4 mg/kg) dosages were determined after a single iv injection with and without concurrent intragastric administration of probenecid (50 mg/kg) in 6 healthy mares. Significant difference was not apparent in the pharmacokinetic values of flunixin meglumine with and without concurrent probenecid administration. Significant (P less-than-or-equal-to 0.05) increase was evident in the 12-hour mean concentration of phenylbutazone (11.45 +/- 1.66-mu-g/ml without probenecid; 14.56 +/-1.20-mu-g/ml with probenecid) along with significant (P less-than-or-equal-to 0.05) reduction in its volume of distribution at steady state associated with concurrent probenecid administration (218.6 +/- 11.52 ml/kg without probenecid; 169.4 +/-9.25 ml/kg with probenecid).