CHEMOTHERAPEUTIC ACTIVITY OF LEVOFLOXACIN (HR-355, DR-3355) AGAINST SYSTEMIC AND LOCALIZED INFECTIONS IN LABORATORY-ANIMALS

Ofloxacin, its optical isomers levofloxacin (HR 355, DR-3355) and D-of loxacin (DR-3354) and ciprofloxacin were administered orally to mice a nd rats which had systemic and localized infections. Both levofloxacin and ciprofloxacin were equally effective in treating systemic murine infections caused by staphylococci, Enterobacteriaceae or Pseudomonas aeruginosa with ED(50)s ranging from 0.18 to 15.8 mg/kg and 0.42 to 16 .3 mg/kg respectively and both these agents were twice as effective as ofloxacin which had an ED(50) 0.41 to 39.7 mg/kg. In contrast, D-oflo xacin was either inactive or exhibited only modest chemotherapeutic ac tivity against the staphylococci and the Gram-negative organisms teste d.When given to mice to treat staphylococcal abscesses and lung infect ions due to Klebsiella pneumoniae DT-S levofloxacin was up to four tim es more effective and produced a more pronounced bactericidal effect a gainst the pathogens in vitro than the reference compounds. Despite po ssessing a similar, if not lesser, in-vitro activity against the infec ting pathogens, levofloxacin was more effective than ofloxacin and cip rofloxacin in rats with localized infections caused by Enterobacteriac eae and P. aeruginosa.