Journal of Clinical Oncology, Vol 12, 1468-1474, Copyright © 1994 by American Society of Clinical Oncology
Pharmacokinetics of undiluted or diluted high-dose etoposide with or without busulfan administered to patients with hematologic malignancies
K Mross, P Bewermeier, W Kruger, M Stockschlader, A Zander and DK Hossfeld
Department of Internal Medicine, University Hospital Eppendorf, Hamburg, Germany.
PURPOSE: We used two different methods to administer high-dose etoposide
(VP-16) during a myeloablative conditioning chemotherapy regimen before
bone marrow transplantation (BMT). VP-16 was administered either diluted
(0.5 mg/mL) or undiluted (20 mg/mL), with or without busulfan. PATIENTS AND
METHODS: Blood samples were drawn from 17 patients during the infusion (6
hours) and thereafter daily until 2 days after BMT. VP-16 concentrations
were measured in all plasma samples by high-performance liquid
chromatography (HPLC) and electrochemical detection, and the results were
analyzed with a pharmacokinetic data analysis system. RESULTS: All
calculated pharmacokinetic parameters in the two patient groups (VP-16
administered diluted or undiluted) were similar. There were no
statistically significant differences in half-lives, mean residence time
(MRT), volume of distribution, total clearance, or area under the curve
(AUC). VP-16 was found in blood samples from eight of 17 patients at the
time of BMT. Significant differences in systemic drug exposure and systemic
clearance were found when patients were grouped according to treatment with
busulfan or with total-body irradiation (TBI). CONCLUSION: The two
administration modes for VP-16, either diluted or undiluted, are
bioequivalent in pharmacokinetic terms. The terminal half-lives were longer
than expected and resulted in significant VP-16 plasma levels at the time
of BMT. The biologic significance remains unclear. Busulfan and/or
concomitant medication with phenytoin influence plasma clearance (clp) and
systemic drug exposure significantly.