DETERMINATION OF 5-FLUOROURACIL AND ITS MAIN METABOLITES IN PLASMA BYHIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY - APPLICATION TO A PHARMACOKINETIC STUDY

This paper describes a relatively simple and sensitive high-performanc e liquid chromatographic assay (HPLC) with ultraviolet absorbance dete ction for 5-fluorouracil (5-FUra) and its two main metabolites, 5-fluo rouridine (5-FUrd) and 5-fluoro-2'-deoxyuridine (5-FdUrd), in plasma. In this study, two plasma clean-up procedures involving addition of in ternal standard, solid-phase and liquid-liquid extractions have been d eveloped. A reversed-phase Kromasil C-18 column was used. The detectio n was performed at 268 nm for 5-FUra and at 275 nm for the two metabol ites. Linear detection responses were obtained for concentrations rang ing from 25 to 1000 ng/ml. The average recovery from plasma was 35, 42 and 48% for 5-FUra, 5-FUrd and 5-FdUrd, respectively. Precision, expr essed as C.V., ranged from 2.7 to 13% and the mean recovery from 94 to 105%. The limits of quantitation and detection of the three analytes were 20 and 10 ng/ml, respectively. The method was used to monitor the pharmacokinetic profile of 5-FUra and its two metabolites in patients with metastatic colorectal cancer.