HPLC-MS/MS determination of a peptide conjugate prodrug of doxorubicin, and its active metabolites, leucine-doxorubicin and doxorubicin, in dog and rat plasma

A HPLC-MS/MS Electrospray (ESI) method was developed and validated to quantify a peptide conjugate prodrug of doxorubicin (Dox-Con) and its active metabolites leucine-doxorubicin (Leu-Dox) and doxorubicin (Dox) in dog and rat plasma. The analytes were extracted from plasma by solid-phase extraction on a Bond Elut(R) C8 cartridge and eluted with chloroform-methanol (2:1). Eluates were evaporated and reconstituted in acetonitrile-5 muM sodium trifluoroacetate in 0.1% aqueous formic acid (20:80) and injected onto a Waters Oasis(R) HLB column. Analytes were eluted from the column with a solvent gradient into the mass analyzer. The ions were quantified in the selected reaction-monitoring mode (SRM), using positive ions, on a triple quadrupole mass spectrometer. The lower limits of quantification for Dox-Con, Leu-Dox, and Dox in plasma, were approximately 5, 1 (dog)/6 (rat), and 0.5 ng/ml, respectively. Intra- and inter-assay accuracy (% of nominal concentration) and precision (%CV) for all analytes were within 15 and 16%, respectively. (C) 2003 Elsevier B.V. All rights reserved.