Pharmacokinetics of sparfloxacin in humans after single oral administration at doses of 200, 400, 600, and 800 mg.

The pharmacokinetics of sparfloxacin at oral doses of 200, 400, 600, and 800 mg were studied in 12 healthy volunteers in a randomized double-blind crossover study. Each dose administration was separated by a 1-week washout period. Plasma and urine samples were collected up to 120 hours postdosing, for determination of free and total (free plus glucurono-conjugated) sparfloxacin levels by high-performance liquid chromatography assay and ultraviolet detection. Mean Cmax values ranged from 705 +/- 158 to 1966 +/- 620 ng/mL for the 200 to 800 mg doses, at median tmax ranging from 4 to 5 hours. A slight decrease of sparfloxacin bioavailability with increasing dose was observed because AUC was 87% to 88% of the expected area when the dose was doubled. The elimination half-life values were constant over the dose range (with values ranging from 18 to 21 hours) as well as the renal clearance. The metabolic ratio conjugated/free drug was not modified by increasing dose.