Simultaneous determination of cytosine arabinoside, daunorubicin and etoposide in human plasma.

A method for simultaneous bioanalysis of the three cytotoxic drugs cytosine arabinoside, daunorubicin and etoposide in human plasma was developed and validated. A HPLC method with ultra-violet and fluorescence detection, preceded by mixed-mode cation-exchange solid phase extraction sample preparation, was used for the quantification of the analytes. The assay was used for the simultaneous measurement of cytosine arabinoside, daunorubicin and etoposide with linearity in the ranges of 13-1500 ng/mL, 15-1000 ng/mL and 52.5-3500 ng/mL, respectively. The chromatographic run-time was 15.5 min. The overall precision (% relative standard deviation) was within 0.2-13.5% and the recovery ranged between 86.1% and 110.1% for the three drugs at all concentrations tested. Plasma samples were stable for at least two months when stored at -20 degrees C. The method was successfully applied to quantification of the three drugs in blood samples from patients undergoing induction treatment for acute myeloid leukaemia, thus demonstrating its suitability for clinical studies.