Simultaneous determination of the combined drugs of ceftriaxone sodium, metronidazole, and levofloxacin in human urine by high-performance liquid chromatography.

To develop a new high-performance liquid chromatography (HPLC) method for simultaneous determination of the combined drugs (ceftriaxone sodium, metronidazole, and levofloxacin) in human urine. Ceftriaxone sodium, metronidazole, and levofloxacin were separated on a Kromasil 100-5 C18 (250 mm × 4.6 mm, 5 μm, AKZO NOBEL, Bohus, Sweden) analytical column, using the mobile phase consisted of 1.5 mM KH(2) PO(4) (pH 4.5) with 0.0125% triethylamine-methnol (70:30, v/v). Ceftriaxone sodium, metronidazole, and levofloxacin were detected by a photodiode-array detector at 247, 320, 292 nm, respectively. Under optimal conditions, the effective separation of ceftriaxone sodium, metronidazole, and levofloxacin was achieved. A good linearity with the correlation coefficients more than 0.999 was demonstrated. The detection limits of ceftriaxone sodium, metronidazole, and levofloxacin were 0.05, 0.01, and 0.25 μg/ml, respectively, and the average recoveries in human urine were in the range from 97.73 to 100.7% with the average relative standard deviation (RSD) in the range of 2.5% and 3.0%. The proposed method was sensitive, accurate, and rapid. This work may provide a reference for clinical rational drug use and methodology for the pharmacokinetics study of the combined drugs.