Iproplatin is a quadrivalent second-generation platinum complex undergoing clinical evaluation. In plasma and urine of patients receiving this drug, iproplatin- and platinum-containing metabolites of iproplatin were separated by reverse-phase gradient high performance liquid chromatography. One of the metabolites was identified by cochromatography and electron impact mass spectrometry as cis-dichloro-bis-isopropylamineplatinum(II), a metabolite formed by reduction of iproplatin. Incubation of iproplatin with ascorbic acid and cysteine, in vitro, indicates that iproplatin can be easily reduced to cis-dichloro-bis-isopropylamineplatinum(II) by reducing agents. It is hypothesized that the reduction of the quadrivalent complex iproplatin to cis-dichloro-bis-isopropylamineplatinum(II) occurs intracellularly.
This work was supported by grants from USPHS (CA-21071) and Bristol Myers Company.