2.8. Pharmacokinetic study in rats

Twelve Wistar male rats weighting 180 to 220 g were supplied by the Animal center of the Shenyang Pharmaceutical University (Shenyang, China). All protocols for animal experiments were approved by Shenyang Pharmaceutical University Animal Care and Use Committee. The validated analytical method was then applied to the pharmacokinetic study after oral administration of JDR (equivalent to 50 mg/kg gemcitabine) or gemcitabine (50 mg/kg) to rats. The rats were randomly divided into two groups and fasted for 12 h until the administration of the drug. Serial blood samples were obtained at 0.083, 0.25, 0.5, 1, 2, 3, 4, 6, 8, 10, 12, 24, 48 h for JDR and 0.25, 0.5, 2, 4, 8, 12, 24 h for gemcitabine, respectively. Blood samples were collected into THU-pretreated heparinized tubes (10 mg/ml) and immediately centrifuged at 3000 × g for 15 min and supernatant (plasma) was stored at −80 °C prior to analysis.