High-performance liquid chromatographic determination of the new quinolone antibacterial agent DU-6859a in human serum and urine using solid-phase extraction with photolysis-fluorescence detection.

A sensitive and specific HPLC method for the determination of DU-6859a (I), a fluoroquinolone antibacterial agent, in human serum and urine was developed. Compound I and the internal standard extracted from serum and urine by means of a Bond Elut C8 LRC cartridge showed recoveries of 96%. The extracts were chromatographed on a reversed-phase column with photolysis-fluorescence detection. This unique detection method was 42.5 times more sensitive than intrinsic fluorescence detection, the limits of detection being in 3.43 ng/ml for serum and 4.35 ng/ml for urine. In addition, I was stable in serum and urine for at least 1 month at -20 degrees C. The proposed method was sensitive and selective enough to apply to pharmacokinetic studies of I in humans after a single oral dose of 100 mg.