The metabolism and pharmacokinetics of fleroxacin in healthy subjects.

A 400 mg dose of fleroxacin was administered orally to six healthy male volunteers. Concentrations of fleroxacin and the N-demethyl and N-oxide metabolites were determined in serum and urine by HPLC. The serum metabolite levels were negligible. The N-oxide metabolite was measured in the serum of five subjects but did not exceed 4% of the corresponding fleroxacin level. N-demethyl fleroxacin was not detected (less than 0.1 mg/l). The urinary recovery of fleroxacin was 49.5% over 72 h; the N-demethyl and N-oxide metabolites accounted for 6.9% and 5.7%, respectively, of the administered dose.