AbstractA high performance liquid chromatographic method to measure plasma and urine fenoprofen levels in equine biofluids is described. Liquid–liquid extraction with diethylether was used to isolate the drug from plasma and urine. The accuracy and reproducibility of the method were within acceptable limits over the concentration range 0–10 μg/mL and 0–20 μg/mL respectively from plasma and urine. Detection limits were 0.05 μg/mL (2 mL plasma) and 0.2 μg/mL (0.5 mL urine). This procedure was applied to ascertain the pharmacokinetics of a 3 g dose of fenoprofen calcium i