Pharmacokinetics of oral firocoxib in un-weaned calves

Sarah Wagner, Virginia R Fajt, Chih-Ping Lo, Christopher J Byrd

Research output: Contribution to journalArticlepeer-review


The objective of this study was to determine the pharmacokinetics of firocoxib after oral administration in un-weaned calves. Eight Holstein calves with a mean age of 36 days and a mean weight of 55 kg were administered a single oral dose of 227 mg firocoxib. The resulting mean dosage was 4.2 mg/kg (range 3.5–5.0 mg/kg). Blood was collected prior to drug administration and at 2, 4, 6, 8, 24, 48, 72, and 96 h after treatment. Firocoxib concentrations in plasma were determined using liquid chromatography–tandem mass spectrometry. Using computer software, pharmacokinetic parameters were found to fit best with a one-compartment model. Mean Cmax was 0.9 μg/ml (range 0.570–1.254), and Tmax was estimated to be 7 h (range 4–8 h). The estimated T1/2 was 15.3 h. The pharmacokinetics of firocoxib after oral dosing are similar to those in dogs, with the exception of a T1/2 that is approximately twice as long. Based on the similar pharmacokineti
Original languageEnglish
Pages (from-to)793-798
JournalJournal of Veterinary Pharamcology and Therapeutics
StatePublished - Apr 2021


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