Amifloxacin (Win49375) is a synthetic antibacterial compound and showed moderate activity against Staphylococcus aureus, with MICs of less than or equal to 2 micrograms/ml.

The activity of Amifloxacin in vitro was comparable to those of norfloxacin and pefloxacin against Enterobacteriaceae and generally greater than those of tobramycin and cefotaxime. Amifloxacin was more active in vitro than carbenicillin and mezlocillin against Pseudomonas aeruginosa isolates[1].

Against systemic, gram-negative bacterial infections in mice, Amifloxacin was generally less active than cefotaxime but more active than gentamicin. WIN 49548, the major piperazinyl-N-desmethyl metabolite of Amifloxacin, was aa effective as the parent drug against experimental infections in mice when given parenterally. When administered orally, however, this metabolite was less potent than Amifloxacin. Amifloxacin was highly active by the oral route, with 50% effective doses within two- to threefold of those obtained with parenteral medication[1].