Population pharmacokinetic analysis of blood concentrations of robenacoxib in dogs with osteoarthritis.

The purpose of this analysis was to investigate whether the recommended daily dosage of 1-2mg/kg robenacoxib provides consistent exposure when administered to dogs with chronic osteoarthritis (OA), and the need for dose adjustment in special patient populations. Data from three prospective, multi-center field studies in 208 OA dogs were analyzed using non-linear mixed effects modeling. A model based assessment was performed with stepwise inclusion and exclusion of population characteristics to explain between-subject variability, and assess the according necessity for dose adjustment. Only the influence of bodyweight on both apparent clearance and volume were found to be significant (p<0.01). No significant influence of sex, age and breed, or kidney and liver variables was identified in this representative sample of OA dogs. The population pharmacokinetic analysis performed showed that the 1-2mg/kg dosage chosen provided consistent robenacoxib exposure in a wide range of canine patients. No other dose adjustment seems necessary.