Pharmacokinetic profile of levofloxacin following once-daily 500-milligram oral or intravenous doses

The pharmacokinetics of once-daily oral levofloxacin (study A) or intravenous levofloxacin (study B) in 40 healthy male volunteers were investigated in two separate randomized, double-blind, parallel-design, placebo-controlled studies, Levofloxacin at 500 mg or placebo was administered orally or intravenously as a single dose on day 1; daily oral or intravenous dosing resumed on days 4 to 10, In a third study (study C), the comparability of the bioavailabilities of two oral and one intravenous levofloxacin formulations were investigated with 24 healthy male subjects in an open-label, randomized, three-way crossover study, Levofloxacin at 500 mg as a single tablet or an intravenous infusion was administered on day 1; following a 1-week washout period, subjects received the second regimen (i.e., the other oral formulation or the intravenous infusion); the third and final regimen was administered following a 1-week washout period, The concentrations of drug in plasma and urine were measured by validated high-pressure liquid chromatography methods, Pharmacokinetic parameters were estimated by noncompartmental methods, In both study A (oral levofloxacin) and study B (intravenous levofloxacin), steady state was attained within 48 h after the start of the multiple dosing on day 1. Levofloxacin pharmacokinetics were linear and predictable for the single and multiple 500-mg, once-daily oral and intravenous dosing regimens, and the values of the pharmacokinetic parameters for the oral and intravenous administrations were similar, Study C indicated that levofloxacin was rapidly and completely absorbed from the oral tablets,,vith mean times to the maximum concentration of drug in serum of approximately 1.5 h and mean absolute bioavailability of greater than or equal to 99%. These results support the interchangeability of the oral and intravenous routes of levofloxacin administration.