2.6.2. Oral Administration and Blood Sampling

The rats were randomly divided into two groups of 6 rats per cage and left to acclimatize to the controlled conditions for 3 days. Prior to the pharmacokinetic experiment, the animals were fasted for 12h, but were allowed free access to water. Each rat was anaesthetized with diethyl ether and fixed on a surgical board. For cannulation, a polyethylene tube containing 50 IU/mL heparin in saline was placed into the right femoral artery of the rat. Then, each of the rats was orally administered with 1 mL aqueous suspension of MTX powder or MTX-loaded solid SASD at a dose of 20 mg/kg using an oral gavage. At predetermined time intervals, ~0.3 mL blood was collected via the cannulated tube and transferred into microtubes containing heparin, which were then centrifuged at 3000× g for 10 min to isolate the plasma.