Application of liquid chromatographic/tandem mass spectrometric method to a urinary excretion study of subutinib and active metabolite in human urine

A novel and selective liquid chromatographic–mass spectrometric method (LC‐MS/MS) has been established and validated for simultaneous determination of subutinib and active metabolite in human urine. Urine samples were extracted by liquid–liquid extraction with ethyl acetate and separated on a Wondasil C₁₈ (150 × 2.1 mm, 3.5 µm), with methanol–0.2% formic acid solution (73:27, v/v) as mobile phase at flow rate of 0.2 mL/min. The linear range was 0.5000–200.0 ng/mL for subutinib and active metabolite, with a lower limit of quantitation of 0.5000 ng/mL. Intra‐ and inter‐run precisions were all <11.8 and 14.3%, and the accuracies were all <4.5 and 5.4%, with the extraction recoveries 88.8–97.5 and 93.8–99.4% for the two analytes, respectively. The carryover values were all <15% for the two anayltes. The method was successfully applied to study urinary excretion of subutinib and active metabolite in human after oral administration of subutinib maleate capsules in fed and fasting states. Copyright © 2015 John Wiley & Sons, Ltd.