The objective of this study was to model the pharmacokinetics (PKs) of robenacoxib in cats using a nonlinear mixed‐effects (NLME) approach, leveraging all available information collected from cats receiving robenacoxib s.c. and/or i.v.: 47 densely sampled laboratory cats and 36 clinical cats sparsely sampled preoperatively. Data from both routes were modeled sequentially using Monolix 4.3.2. Influence of parameter correlations and available covariates (age, gender, bodyweight, and anesthesia) on population parameter estimates were evaluated by using multiple samples from the posterior distribution of the random effects. A bicompartmental disposition model with simultaneous zero and first‐order absorption best described robenacoxib PKs in blood. Clearance was 0.502 L/kg/h and the bioavailability was high (78%). The absorption constant point estimate (Ka = 0.68 h−1) was lower than beta (median, 1.08 h−1), unveiling flip‐flop kinetics. No dosing adjustment based on available covariates information is advocated. This modeling work constitutes the first application of NLME in a large feline population.

The objective of the study was to assess the cardiovascular effects of intravenous (IV) dosing with robenacoxib (Onsior ) in conscious adult healthy beagle dogs. The study employed a randomized, open, placebo-controlled, four-phase Latin square design. A total of eight dogs received a single dose of 2 mg/kg and 4 mg/kg IV robenacoxib (test groups), 2 mg/kg subcutaneous (SC) robenacoxib (reference dose and route), and IV isotonic saline (control). There were no significant differences between groups for clinical observations, buccal mucosal bleeding time or blood hematology, coagulation, and clinical chemistry variables in all eight dogs. In a subset of four dogs, no significant differences between groups were detected using telemetric assessment for arterial blood pressure, heart rate, electrocardiogram, or body temperature over 8 hr postdose. In conclusion, no significant cardiovascular effects were detected after a single IV dose of 2 or 4 mg/kg robenacoxib in conscious healthy dogs.