[In vitro and in vivo antibacterial activities of a new quinolone derivative, FD501].

FD501 is a newly synthesized quinolone derivative with aminoazepine group at the C-7 position. The in vitro and in vivo antibacterial activities of FD501 were investigated comparing with those of norfloxacin, ofloxacin, ciprofloxacin and sparfloxacin. The in vitro antibacterial activities of FD501 against Gram-positive bacteria including methicillin-resistant Staphylococcus aureus, were equal to or higher than those of other quinolones. But its activities against Gram-negative bacteria were equal to or lower than those of other quinolones. Minimum inhibitory concentrations of FD501 against Gram-positive bacteria were similar to that of sparfloxacin. The bactericidal activity may be due to the inhibition of the DNA super-coiling activity of DNA gyrase. The area under the serum concentration-time curve of FD501 in rats following oral administration was larger than norfloxacin and ciprofloxacin and smaller than those of ofloxacin and sparfloxacin.