Volume 46, Number 6 (November - December 2001)

Key words: etoposide, HPLC method, total and unbonded etoposide concentration, bone marrow transplantation

Etoposide is extensively used in anticancer therapy and highly bound (95%) to albumin in human plasma. The monitoring of total and free concentration of this drug could help individualize dosage regimen to improve clinical response and reduce hematological toxity. A simple HPLC method for quantification of total and free etoposide in plasma is described. The method involves the addition of teniposide as an internal standard, chloroform extraction and HPLC separation on a reversed phase Nucleosil Phenyl column using methanol-water-acetic acid (55:44:1) as a mobile phase. The effluent from the column was monitored at 240 nm. The method is selective, reproducible and sensitive. The detection limit for etoposide was 0.05 mg ml^-1. The fasibility of this method has been tested in 3 patients with bone marrow transplantation receiving etoposide during intravenous infusion. Any interference was not found from endogenous substances and co-administered with etoposide drugs (amicacin sulfate, ceftazidime, teicoplanin, ciclosporine).