HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHIC DETERMINATION OF ETOPOSIDE IN PLASMA

A rapid and sensitive high-performance liquid chromatographic method for the determination of etoposide in plasma is described. Etoposide and the internal standard phenacetin were extracted with 1,2 dichloroethane. Separation was achieved using a phenyl (300 x 3.9 mm, 5-mu-m packing) analytical column. The effluent was monitored by UV detection at a wavelength of 233 nm. The etoposide peak-height ratio to the internal standard was linearly related to etoposide plasma concentration over a range of 0.1 - 50-mu-g/mL (r2 = 0.998). Reliability of the assay was excellent with both the within-and between- day coefficient of variation < 5%. We have observed this method to be both sensitive and reliable, qualities important in our recent application of this method in a high-dose etoposide pharmacokinetic study in cancer patients.