HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHIC ASSAY OF A NEW FLUOROQUINOLONE, LB20304, IN THE PLASMA OF RATS AND DOGS

High-performance liquid chromatographic method was developed for the d etermination of LB 20304 (compound 1) in the plasma of rats and dogs. The analyte was deproteinized with 1 volume of methanol and 1/2 volume of 10% zinc sulfate, and the supernatant was injected onto a reversed -phase HPLC column. The mobile phase was a mixture of 24 parts of acet onitrile and 76 parts of 0.1% trifluoroacetic acid. The flow rate was 1 ml/min, and the effluent was monitored by fluorescence detector at a n excitation wavelength of 337 nm and an emission wavelength of 460 nm . The retention lime of compound 1 was 6.3 min. The assay of compound 1 was linear over the concentration range-of 0.2-100 eta g/ml in the p lasma of rats and dogs. The lower limit of quantification was 0.2 mu g /ml using 100 mu l of plasma with a 97-99% accuracy and a 12-14% preci sion. In the 0.5, 5, and 50 mu g/ml quality control samples, the intra - and inter-day accuracy were 88-95% and 88-97%, whereas intra- and in terday precision were 0.5-6.6% and 0.2-9.3%, respectively, in the plas ma of rats and dogs. The recoveries were 68-71% independent of concent ration and species in the plasma. No interferences from endogenous sub stances were observed. Taken together, the above HPLC assay method by deproteinization and fluorescence detection was suitable for the deter mination of compound 1 in the preclinical pharmacokinetics.