2.5 PK assessment
Approximately 3 mL blood was collected into heparin lithium
anticoagulant tubes, gently reversed, and mixed 6–10 times. The plasma
concentration of famitinib and SHR116637 was determined by liquid
chromatography-tandem mass spectrometry (LC-MS/MS) at the Frontage
Holdings Corporation (Shanghai). The analytical method was developed and
validated to meet the standard operating procedure established by the
sponsor. Plasma samples were stored at ‑80°C, and the detection was
completed within the storage time limit (long-term stability period was
160 days). The concentration range of calibration standards for
famitinib and SHR116637 was both 0.05-100 ng/mL. In each analytical
batch, the number of quality control samples (QC) accounts for more than
5% of the total number of samples, and at least two samples at each
concentration level per time. For famitinib, the inter-run precision was
2.9–4.1%,while the inter-run accuracy ranged between 1.3-3.1%. For
the metabolite SHR116637, the inter-run precision and accuracy were
1.6-3.4% and -2.7-1.1%, respectively.