Pharmacokinetics of the novel COX‐2 selective inhibitor vitacoxib in cats: The effects of feeding and dose

The purpose of this study was to determine the pharmacokinetics and dose‐scaling model of vitacoxib in either fed or fasted cats following either oral or intravenous administration. The concentration of the drug was quantified by UPLC‐MS/MS on plasma samples. Relevant parameters were described using noncompartmental analysis (WinNonlin 6.4 software). Vitacoxib is relatively slowly absorbed and eliminated after oral administration (2 mg/kg body weight), with a T_max of approximately 4.7 hr. The feeding state of the cat was a statistically significant covariate for both area under the concentration versus time curve (AUC) and mean absorption time (MAT_fed). The absolute bioavailability (F) of vitacoxib (2 mg/kg body weight) after oral administration (fed) was 72.5%, which is higher than that in fasted cats (F = 50.6%). Following intravenous administration (2 mg/kg body weight), Vd (ml/kg) was 1,264.34 ± 343.63 ml/kg and Cl (ml kg^?1 hr^?1) was 95.22 ± 23.53 ml kg^?1 hr^?1. Plasma concentrations scaled linearly with dose, with C_max (ng/ml) of 352.30 ± 63.42, 750.26 ± 435.54, and 936.97 ± 231.27 ng/ml after doses of 1, 2, and 4 mg/kg body weight, respectively. No significant undesirable behavioral effects were noted throughout the duration of the study.