PHARMACOKINETICS OF SPARFLOXACIN IN HUMANS AFTER SINGLE ORAL-ADMINISTRATION AT DOSES OF 200-MG, 400-MG, 600-MG, AND 800-MG

The pharmacokinetics of sparfloxacin at oral doses of 200, 400, 600, a nd 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 gluc urono-conjugated) sparfloxacin levels by high-performance liquid chrom atography assay and ultraviolet detection. Mean Cmax values ranged fro m 705 +/- 158 to 1966 +/- 620 ng/mL for the 200 to 800 mg doses, at me dian 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 eliminatio n half life values were constant over the dose range (with values rang ing from 18 to 21 hours) as well as the renal clearance. The metabolic ratio conjugated/free drug was not modified by increasing dose.