Pharmacokinetics of teniposide (VM26) and etoposide (VP16-213) in children with cancer

The clinical pharmacokinetics of VM26 and VP16-213 were assessed in 15 children (median age 10 years) with acute leukemia, using a new high-performance liquid chromatography—electrochemical assay. Pharmacokinetic parameters were calculated by both model-dependent and compartment model-independent methods. These studies demonstrated substantial differences in the central volumes of distribution (VDc), steady-state volumes of distribution (VDss) and systemic clearances (Cls) of VM26 and VP16-213; with the VDc, VDss, and Cls all being smaller for VM26. Systemic clearances determined by model-independent methods were 5.2±1.0 ml/min/m2 (mean±SD) for VM26 and 17.8±11.2 ml/min/m2 for VP16-213. The major metabolites detected in serum and urine were the hydroxy acids. Low levels of the picro-lactone isomers were detected in some patients while the aglycones were not detected in the serum or urine of any patients.