Bioanalytical method for the quantification of sunitinib and its n-desethyl metabolite SU12662 in human plasma by ultra performance liquid chromatography/tandem triple-quadrupole mass spectrometry

A rapid and sensitive ultra performance liquid chromatography/tandem mass spectrometry (UPLC-MS/MS) method has been developed and validated for the quantitative determination of sunitinib and its n-desethyl metabolite SU12662, in 100 mu l aliquots of human potassium EDTA plasma with deuterated sunitinib as internal standard. As sunitinib was found to be extremely sensitive to light causing rapid conversion of the Z (cis)-isomer to the E (trans)-isomer, the sample extraction and cleaning-up were performed under sodium-light and in amber vials. The extraction involved a simple liquid-liquid extraction with tert-butyl methyl ether. Chromatographic separations were achieved on an Aquity UPLC (R) BEH C-18 1.7 mu m, 2.1 mm x 50 mm column eluted at a flow rate of 0.250 ml/min on a gradient of acetonitrile. The overall cycle time of the method was 4 min, with elution times of 1.05, 1.43, 0.95, and 1.34 min, for the E (trans)- and Z (cis)-isomers of sunitinib and the E (trans)- and Z (cis)-isomers of SU12662, respectively. The multiple reaction monitoring transitions were set at 399 > 326 (m/z), at 371 > 283 (m/z) and at 409 > 326(m/z) for sunitinib, SU12662 and the internal standard, respectively. The calibration curves were linear over the range of 0.200 to 50.0 ng/ml with the lower limit of quantitation validated at 0.200 ng/ml for both sunitinib and SU12662. The within-run and between-run precisions were within 11.7%, while the accuracy ranged from 90.5 to 106.8%. (C) 2009 Elsevier B.V. All rights reserved.