Urine bactericidal activity of pefloxacin versus norfloxacin in healthy female volunteers after a single 800-mg oral dose

Summary In an open randomised crossover study the antibacterial activity of pefloxacin and norfloxacin was assessed in the urine after a single 800-mg oral dose in 14 healthy female volunteers. Pefloxacin demonstrated lower peak concentrations in the urine than norfloxacin (mean, 217.2 mg/l versus 492.9 mg/l as determined by the microbiological assay) but pefloxacin was present over a longer period of time in sufficient concentrations than norfloxacin. Mean urine levels of at least 2 mg/l were present for 7 days after pefloxacin administration and 2 days after norfloxacin administration as determined by the microbiological assay. Overall, the urinary recovery of pefloxacin and norfloxacin amounted to 49.3% and 25.1%, respectively, of the total administered dose. The average urine bactericidal activity against the five test organisms was as follows: against reference strainEscherichia coli ATCC 25922 susceptible to nalidixic acid (Nal-S) for 5 days with pefloxacin and 2 days with norfloxacin; against three clinical isolates, one strain each ofE. coli resistant to nalidixic acid (Nal-R),Klebsiella pneumoniae Nal-R, andStaphylococcus saprophyticus, for 3 days with pefloxacin and 24 h with norfloxacin; and against a clinical isolate ofEnterococcus faecalis for 2 days with pefloxacin and 12 h with norfloxacin. In conclusion, pefloxacin as a single dose proved to have sufficiently high and long-lasting urine bactericidal activity against urinary pathogens. These findings support the results of a meta-analysis of seven clinical trials in patients with uncomplicated lower UTI, demonstrating a single oral dose of 800 mg pefloxacin to be as effective as a conventional treatment with comparative drugs [21].