Determination of levofloxacin in plasma by HPLC and its pharmacokinetics study

Objective To develop an HPLC-UV assay for the determination of levofloxacin in human plasma, and evaluate the pharmacokinetics and bioequivalence. Methods After being deproteined by perchloric acid (20%, v/v), samples were separated by HPLC on a reversed-phase C18 column with a mobile phase of water-acetonitrile- triethylamine-acetic acid (81∶19∶0.5∶1, V/V/V/V)and with the flow rate 1.0 ml · min-1. A randomized crossover design was performed in 20 healthy volunteers. In the two study periods, a single dose of two tablets was administered to each volunteer. Results The calibration curve was linear among the range 0.05 ～ 5 μg·ml-1 T1/2. Tmax and Cmax were (6.46 ± 0.77) h, (0.9 ± 0.3) h and ( 2.74 ± 0.75 ) ug/L for the test tablet and (6.58 ± 1) h, (1.0 ± 0.59) h and (2.55 ± 0.54)ug/L for the reference tablet, re spectively. The relative bioavailability of the test tablet was(105.55 ± 12.30)%. The results of variance analysis and two one-sided t-test showed that there was no significant difference between the two preparations in the AUC and Cmax. Conclusion The assay was proved to be sensitive,accurate and convenient. The two preparations were bioequivalent. Key words: levofloxacin;  pharmacokinetics;  HPLC