On the other hand, norfloxacin (NFLX, 2) 4 containing a fluorine atom and a piperazinyl group at the 6-and 7-position of quinolone, respectively, and its 8-fluor0 derivative (3) 5apb were found to show excellent antibacterial activities and a broad antibacterial spectrum. But the former has been reported to show low blood concentrations and low urinary recoveries after oral administration to animals, B and the latter was confiied to show significantly