Comparative Pharmacokinetics of Subcutaneous Tolfenamic Acid Under Two Different Anesthetic Protocols in Cats Undergoing Ovariohysterectomy

The aim of this research was to determine the effect of different anesthesia protocols on the pharmacokinetics of tolfenamic acid in cats undergoing ovariohysterectomy. The research involved 12 cats that underwent ovariohysterectomy. The cats were randomly divided into two equal groups: one (n = 6) receiving xylazine–ketamine and the other (n = 6) receiving propofol–isoflurane anesthesia. Tolfenamic acid was administered subcutaneously at a dose of 4 mg/kg 30 min prior to ovariohysterectomy in both groups. The plasma samples were analyzed for tolfenamic acid using high-performance liquid chromatography (HPLC)-UV. The terminal elimination half-life (t1/2λz), area under the curve (AUC0-last), maximum plasma concentration (Cmax), and time to reach peak plasma concentration (Tmax) values after xylazine–ketamine anesthesia were determined to be 3.30 h, 42.17 h*µg/mL, 6.34 µg/mL, and 2 h, respectively. Tolfenamic acid in the propofol–isoflurane anesthetic group showed shorter t1/2λz and Tmax than the xylazine–ketamine group but a greater Cmax. However, AUC0-last was similar in both anesthesia groups. These results showed that the pharmacokinetics of tolfenamic acid may vary depending on the anesthesia protocol used in ovariohysterectomy. However, there is a need to evaluate the efficacy of tolfenamic acid in cats under both anesthesia regimens.