2.15 Pharmacokinetic study
All animal experimental protocols were carried out strictly in accordance with the principles and procedures approved by the Animal Ethics Committee of Northwest A&F University. Animal studies are reported in compliance with the ARRIVE guidelines (Kilkenny, Browne, Cuthill, Emerson, & Altman, 2010; McGrath & Lilley, 2015) and with the recommendations made by the British Journal of Pharmacology . Male Sprague-Dawley rats (200-220 g) were purchased from Sino-British Sippr/BK Laboratory Animal Ltd. (Shanghai, China). Rats were fasted but allowed free access to water for 12 h prior to the pharmacokinetic study. The rats were randomized into two groups for intravenous or intraperitoneal injection, the dosages of which were set at 20 and 40 mg/kg, respectively. Each group contained five or six rats. Blood samples were collected from the orbital plexus into heparinized centrifuge tubes at 5, 10, 20, 40, 60, 120, 240, 360, 720, and 1440 min after the administration. Then the whole blood was centrifuged at 4000 × g for 10 min at 4 °C. The obtained plasma was frozen and stored at -80 °C until further analysis. Pharmacokinetic parameters were calculated by WinNonlin software (Pharsight Corporation, Princeton, NJ, USA) based on non-compartmental method. Mean plasma concentration-time curves of TA in rats were plotted by GraphPad Prism 5 (GraphPad software Inc., CA, USA).