HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHIC ASSAY FOR THE DETERMINATION OF THE NOVEL ETOPOSIDE DERIVATIVE DIMETHYLAMINOETOPOSIDE (NK611) AND ITS METABOLITES IN URINE OF CANCER-PATIENTS

A simple, reproducible and specific urine assay for the novel epipodop hyllotoxin derivative dimethylaminoetoposide (NK611, I) its picro form (III), the N-demethyl metabolite (II) and its picro form (IV) is repo rted. The method involves the addition of Pr-NK611 as internal standar d, chloroform extraction and HPLC separation on a Nova-Pak C-18 column with a mobile phase of acetonitrile-0.05 M KH2PO4 (pH 6.4) (23:77, v/ v). UV detection was used with absorbance monitored at 205 nm and the limit of quantification was 100 ng/ml. The intra- and inter-day precis ions were within the ranges 1.1-3.4% and 1.9-2.4% for all analytes and the accuracy was 101-107%. The extraction recovery was more than 88% for I, II and TV and more than 83% for m. The assay is applicable to t he urinary monitoring of I-IV in clinical pharmacokinetic investigatio ns.