Dose-ranging study of fleroxacin for treatment of uncomplicated Chlamydia trachomatis genital infections.

Men and women with suspected or proven genital infections caused by Chlamydia trachomatis were enrolled in a double-blind study to evaluate the efficacy and tolerability of fleroxacin. Patients received either 400, 600, or 800 mg once daily for 7 days and were monitored approximately 2, 4, and 7 weeks after initiation of therapy. In men monitored for at least 6 weeks or until failure of the therapy, fleroxacin failed to eradicate C. trachomatis in three of eight on the 400-mg regimen, in one of four on the 600-mg regimen, and in four of seven on the 800-mg regimen. All five women monitored for at least 6 weeks became culture negative. There was no association between in vitro susceptibility of C. trachomatis to fleroxacin and outcome, with MICs being 4 to 8 migrograms/ml for almost all isolates tested. Among those with positive cultures for Ureaplasma urealyticum initially, the first follow-up cultures remained positive in 8 (29%) of 28 men and 8 (50%) of 16 women. Independent of culture results, men with nongonococcal urethritis receiving 800 mg of fleroxacin were significantly more likely to show a clinical response than men receiving 400 or 600 mg (93 versus 54%). Adverse events were frequent, often severe, and dose related. Insomnia and photosensitivity reactions were the most important. The adverse reactions and unacceptably high rates of microbiologic failure resulted in premature termination of the study.