Pharmacokinetics and metabolism of firocoxib in horses after oral administration

AGRO 8

Valerie Kvaternick, valerie.kvaternick@merial.com1, Matthias Pollmeier2, Peter D. Hanson3, and James B Fischer1. (1) PKDM, Merial, 631 Route 1 South, North Brunswick, NJ 08902, (2) Opérations Cliniques Animaux de Production, Merial SAS, CRSV, PIPA, 1, allée des Cyprès, St. Vulbas, France, (3) PR&D, Merial, 3239 Satellite Blvd, Duluth, GA 30096
Firocoxib (EQUIOXX® Merial) is a newly-approved second generation coxib for the relief of pain and inflammation associated with osteoarthritis in the horse. The pharmacokinetic study was a two period crossover design with a 20-day washout period. After a single oral dose, firocoxib was rapidly absorbed (Tmax = 3.9 hr) with a maximum concentration of 75 ng/mL. Firocoxib plasma concentrations decreased exponentially and parallel to those following intravenous administration. The terminal elimination half-life was 30 hours. The absolute bioavailability was 79%. The metabolism of firocoxib was evaluated after horses were administered seven consecutive daily oral doses of 14C-firocoxib. The majority of the radioactivity was excreted within 3 days after the last administered dose and accounted for approximately 83.5% of the total radioactive dose. The majority of the radioactivity was eliminated in the urine (~65-70%) with about 15-18% excreted in the feces. The major inactive metabolites were descyclopropylmethylfirocoxib, the dealkylated parent, and its glucuronide conjugate.
 

Agrochemical Residue & Metabolism Chemistry
8:55 AM-11:20 AM, Sunday, August 19, 2007 BCEC -- 259B, Oral

Division of Agrochemicals

The 234th ACS National Meeting, Boston, MA, August 19-23, 2007