Quantification of sunitinib in human plasma by high-performance liquid chromatography-tandem mass spectrometry.

A rapid, sensitive and specific method was developed and validated using LC/MS/MS for determination of sunitinib in human plasma. Sample preparation involved a liquid-liquid extraction by the addition of 0.2mL of plasma with 4.0mL tert-butyl-methyl-ether extraction solution containing 25ng/mL of the internal standard clozapine. Separation of compounds was achieved on a C18 (50mmx2.1mm i.d., 3.5microm) analytical column using a mobile phase consisting of acetonitrile/H20 (65:35, v/v) containing 0.1% formic acid and isocratic flow at 0.150mL/min for 3min. The analytes were monitored by tandem-mass spectrometry with electrospray positive ionization. Linear calibration curves in human plasma were generated over the range of 0.2-500ng/mL with values for the coefficient of determination of >0.9950. Within- and between day precision and accuracy were < or =10%. The method was applied to the quantitation of sunitinib in plasma samples from a patient receiving daily oral therapy with sunitinib.