Robenacoxib (trade name Onsior) is a non-steroidal anti-inflammatory drug (NSAID) used in veterinary medicine for the relief of pain and inflammation in cats and dogs. In an inflammation model in cats, Robenacoxib had analgesic, anti-inflammatory and antipyretic actions with a rapid onset of action (0.5 h). In an in vitro whole blood assay in cats, Robenacoxib demonstrated selective COX-2 inhibition. After oral administration of robenacoxib tablets at 1 mg/kg without food, peak blood concentrations are attained rapidly with a median Tmax of 0.5 h, a mean Cmax of 1159 ng/ml and a mean AUC of 1337 ng*h/ml. Robenacoxib persists longer in the inflammatory exudate of a tissue cage model than in blood. The median Robenacoxib elimination half-life in exudate was about 27 hours versus 2.5 hours for blood. Robenacoxib is extensively metabolized by the liver in cats. The systemic exposure of lactam metabolite is about 25% of Robenacoxib exposure following oral administration to fed cats. Further, the systemic exposure to lactam appears to be two-fold greater in fed cats than fasted cats. Apart from one lactam metabolite, the identity of other metabolites is not known in cats.