MULTIPLE-DOSE PHARMACOKINETICS AND SAFETY OF RUFLOXACIN IN NORMAL VOLUNTEERS

The pharmacokinetics and safety of rufloxacin were evaluated in a double-blind, placebo-controlled study. Two groups of 16 healthy volunteers were given a single oral loading dose of 400 or 600 mg of rufloxacin on day 1 of the study. A single daily maintenance dose of 200 or 300 mg was then administered for a further 9 days; in addition, four subjects in each group received placebos. Rufloxacin levels in plasma and urine were determined by high-performance liquid chromatography. Following the initial dose, the mean (+/- standard error of the mean) peak concentrations of rufloxacin in plasma were 3.35 +/- 0.12-mu-g/ml in the 400-mg group and 4.54 +/- 0.19-mu-g/ml in the 600-mg group. They were generally reached 2 to 3 h after dosing. At the end of treatment, maximum levels in plasma rose to 4.51 +/- 0.15 and 7.20 +/- 0.25-mu-g/ml in the 400-mg and 600-mg groups, with a mean extent of accumulation (fold) of 3.1 +/- 0.1 and 3.3 +/- 0.1. For the 400-mg and 600-mg groups, the elimination half-lives were 40.0 +/- 1.5 and 44.0 +/- 1.3 h, mean residence times were 57.8 +/- 2.2 and 63.7 +/- 1.8 h, apparent volumes of distribution were 132 +/- 4 and 139 +/- 5 liters, and apparent total body clearances were 39 +/- 1 and 44 +/- 4 ml/min, assuming complete bioavailability. Of the total dose administered, the percentages excreted in urine were 49.6 +/- 1.3 and 51.1 +/- 2.1%, with renal clearances of 21 +/- 1 and 22 +/- 2 ml/min, for the 400-mg and 600-mg groups. On the whole, the treatments were well tolerated, but some minor adverse events (mainly headache, insomnia, or abdominal discomfort) were reported for 7 subjects on the low-dose regimen, for 12 subjects on the high-dose regimen, and for 3 subjects taking placebos. No abnormalities were detected in the laboratory examinations or in ocular function tests. This study shows that a 200-mg daily oral dose of rufloxacin preceded by a loading dose of 400 mg are well tolerated and produce steady-state concentrations in plasma above the MIC for most susceptible pathogens.