Sample preparation and estimation of plasma concentration of 3-deazauridine by high-performance liquid chromatography

A rapid and simple procedure for liquid chromatographic analysis of plasma 3-deazauridine (3-DU), an antineoplastic agent, was developed. The plasma was extracted with methanolic silver acetate to remove interfering ultraviolet-absorbing materials and the 3-DU partially purified on a small anion exchange column prior to chromatography on a reverse-phase (C18) column. 2'-O-Methyl-3-deazauridine was used as an internal standard. The mobile phase was 0.1 M ammonium acetate, pH 4.0, containing 5% methanol. The 3-DU was identified by its retention time and its characteristic ultraviolet absorbance ratio (280/254 nm) of 3.0. This method was used to determine the plasma concentration of 3-DU in three patients with acute leukemia. The patients received a 36-h infusion of 3-DU at a rate of 5.0 mg/kg/h. The mean steady-state plasma concentration of 3-DU at the end of the infusion was 22.1 micrograms/ml (range, 13.6-42.8 micrograms/ml) and the mean elimination half-life was 109 min (range, 92-136 min). 2,4-Dihydroxypyridine, a potential metabolite of 3-DU, was not detected in any of the plasma samples of the patients receiving a 3-DU infusion.