Plasma firocoxib concentrations after intra-articular injection of autologous conditioned serum prepared from firocoxib positive horses

Mean (±standard error of the mean, SEM) plasma concentration of firocoxib 4 h following the second dose was 33.3 ± 4.72 ng/mL. Mean (±SEM) firocoxib concentration in ACS was 35.4 ± 4.47 ng/mL. Fourteen days following the second and last dose of firocoxib, mean plasma concentration was below the lower limit of detection (LOD = 1 ng/mL) in all horses. Following IA injection of ACS, plasma concentrations of firocoxib remained below LOD at all times in all horses. ACS generated from horses with therapeutic plasma concentrations of firocoxib did not contain sufficient firocoxib to lead to a positive plasma drug test following IA administration.