An HPLC–PDA method for determination of alectinib concentrations in the plasma of an adolescent

Alectinib is a central nervous system-active small molecule anaplastic lymphoma kinase (ALK) inhibitor that is effective in the treatment of patients with ALK positive tumors, including advanced non-small cell lung cancers and lymphomas. A simple, isocratic high-performance liquid chromatography-photo diode array detection (HPLC-PDA) assay for measurement of alectinib in human plasma is described. Alectinib is extracted from the plasma matrix by addition of methanol, followed by centrifugation and acidification with 0.1% formic acid. It elutes with a run time of 4.6 min using a 250 mm x 4.6 mm RP-C18 column with 0.1% aqueous formic acid and methanol (35:65, v/v) and a flow rate of 1 mL/min. Detection was at 339 nm. Linear calibration plots were achieved in the range of 0.1-20 mu g/mL for alectinib (r(2)= 0.9996). With limits of detection and quantification of 0.05 and 0.1 mu g/ mL, respectively, and excellent precision (%CV < 10%), accuracy (bias < +/- 12%), and recovery (>97%) within the 1-20 mu g/mL concentration range, this assay was suitable for measuring pre-dose alectinib concentrations in an adolescent receiving 600-mg doses twice daily.