Among the major commercially available
fluoroquinolones,
ciprofloxacin was inactive against M. leprae in mice;
pefloxacin was active, 50 mg/kg daily showed bacteriostatic activity but 150 mg/kg daily displayed bactericidal activity;
ofloxacin was more active than
pefloxacin, 50 mg/kg daily exerted the same level of bactericidal effect as
pefloxacin 150 mg/kg daily, and
ofloxacin 150 mg/kg displayed profound killing activity. Two clinical trials with 6 months of
pefloxacin and/or
ofloxacin in 31 previously untreated lepromatous patients have been completed.
Pefloxacin 400 mg twice daily or 800 mg once daily or
ofloxacin 400 mg once daily were equally effective; definite clinical improvement with drastically decrease of morphological index to the baseline were observed in all patients at 2 months after beginning of treatment; about 99.99%, or 4 "logs", of organisms viable on Day 0 were killed by 22 doses of either
pefloxacin or
ofloxacin. The side effects from the two trials were rare and mild, and the patients tolerated extremely well the combinations of
pefloxacin/
ofloxacin plus multidrug
therapy (MDT) regimen for
multibacillary leprosy recommended by WHO. The amount of
rifampicin-resistant mutants in lepromatous patients before treatment are no more than 4 "logs", thus, all
rifampicin-resistant mutants may be eliminated by 22 doses of either
pefloxacin or
ofloxacin. It is, therefore, possible that the combination of
ofloxacin and
rifampicin may considerably shorten the required duration of MDT.