SIMULTANEOUS DETERMINATION OF 5'-DEOXY-5-FLUOROURIDINE, 5-FLUOROURACIL AND 5,6-DIHYDRO-5-FLUOROURACIL IN SERUM BY LIQUID-CHROMATOGRAPHY WITH DIODE-ARRAY UV DETECTION

5,6-Dihydro-5-fluorouracil (5-FUH2), the main catabolite of the antica ncer drug 5-fluorouracil (5-FU), can be quantitated in human serum sim ultaneously with the pro-drug 5'-deoxy-5-fluorouridine (5'-dFUR), the parent drug 5-FU and the anabolites 5-fluorouridine and 2'-deoxy-5-flu orouridine by gradient elution-reversed phase liquid chromatography co upled to diode array UV detection. The analytes were extracted (after protein precipitation with ammonium sulphate) with ethyl acetate-isopr opanol (90:10, v/v). The average recovery for 5-FUH2 was 78.0% at 0.5 mu g/ml level. 5-FUH2 response was linear over three concentration dec ades and its detection limit was 200 ng/ml of serum. The analytical pr ocedure has been used for simultaneous monitoring of 5'-dFUR, 5-FU and 5-FUH2 levels in the serum of a patient under 5'-dFUR chemotherapy.