WIN 49375 (
amifloxacin) is a synthetic
antibacterial agent of the
quinolone class. It is similar in chemical structure to
pefloxacin but differs by containing a methylamino, rather than an ethyl, substituent at the 1-N position. The activity of
WIN 49375 in vitro was comparable to those of
norfloxacin and
pefloxacin against Enterobacteriaceae and generally greater than those of
tobramycin and
cefotaxime.
WIN 49375 was more active in vitro than
carbenicillin and
mezlocillin against Pseudomonas aeruginosa isolates and showed moderate activity against Staphylococcus aureus, with MICs of less than or equal to 2 micrograms/ml. The in vitro activity of
WIN 49375 was not markedly affected by the presence of human serum, the size of the bacterial inoculum, or changes in pH between 6 and 8. Against systemic,
gram-negative bacterial infections in mice,
WIN 49375 was generally less active than
cefotaxime but more active than
gentamicin. WIN 49548, the major piperazinyl-N-desmethyl metabolite of
WIN 49375, 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
WIN 49375.
WIN 49375 was highly active by the oral route, with 50% effective doses within two- to threefold of those obtained with parenteral medication.