Levofloxacin. A review of its antibacterial activity, pharmacokinetics and therapeutic efficacy

Rapid stereospecific high-performance liquid chromatographic determination of levofloxacin in human plasma and urine

A rapid high-performance liquid chromatographic (HPLC) method for the determination of levofloxacin in human plasma and urine has been validated. A single-step liquid-liquid extraction procedure was used to isolate levofloxacin from the biological matrix prior to quantitative analysis. The compound was separated on an Inertsil C18 reversed-phase HPLC column and quantified by measuring the UV absorbance at 330 nm. The stereospecificity was achieved in the ligand-exchange mode by incorporating chiral reagents directly into the HPLC mobile phase. Ciprofloxacin was used as the internal standard. The method was linear from 0.08 to 5.18 micrograms ml-1 of levofloxacin in plasma and from 23 to 1464 micrograms ml-1 in urine. The overall utility of the method is reflected in its high sample throughput and easy adaptability to robotic automation, thus making the procedure suitable for pharmacological and pharmacokinetic studies of levofloxacin.

In vivo oral efficacy of levofloxacin for treatment of systemic Pseudomonas aeruginosa infections in a murine model of septicemia

The in vivo efficacies of levofloxacin and ciprofloxacin in lethal, systemic Pseudomonas aeruginosa infections in mice were compared. MICs of levofloxacin and ciprofloxacin ranged from 0.5 to 2.0 micrograms/ml and from 0.12 to 1.0 microgram/ml respectively. Infecting doses ranged from 5.0 x 10(1) to 3.2 x 10(3) CFU per mouse, depending on the isolate. Test fluoroquinolones were administered orally at 1 h (single dose) or at 1 and 3 h (divided dose) postinfection, with 10 infected mice used for each of six concentrations of each fluoroquinolone tested (1 to 40 mg/kg of body weight) in each dosing regimen. Whether given in a single or a divided dose, the total daily dose was the same for each fluoroquinolone. For mice treated 1 h postinfection with levofloxacin and ciprofloxacin, the effective doses for 50% of the infected mice ranged from 2.09 to 13.80 mg/kg and from 2.34 to 11.22 mg/kg, respectively, and for those treated 1 and 3 h postinfection, the effective doses for 50% of the infected mice ranged from 3.71 to 16.98 mg/kg and from 2.95 to 13.18 mg/kg, respectively. Although the potency varied for both levofloxacin and ciprofloxacin among all strains of P. aeruginosa tested, there were small differences within the same strain for levofloxacin and ciprofloxacin when given in the same dosing regimen. Levofloxacin proved nearly as effective as ciprofloxacin against a systemic P. aeruginosa infection in mice.

Local absorption kinetics of levofloxacin from intestinal tract into portal vein in conscious rat using portal-venous concentration difference

PURPOSE

The local absorption kinetics of levofloxacin from the intestinal tract was quantitatively evaluated by simultaneously measuring the portal and venous plasma concentrations in a conscious rat.

METHODS

The venous and upper portal blood vessels were cannulated through the jugular and pyloric veins, respectively. After oral or intravenous administration of levofloxacin, portal and venous concentrations of levofloxacin were simultaneously monitored. The absorption rate from the intestine into the portal system was calculated from the portal-venous difference in the plasma concentration of levofloxacin, considering the distribution of levofloxacin into erythrocytes. Portal blood flow rate was newly measured by an electromagnetic flow meter.

RESULTS

There was little portal-venous difference after an intravenous dose of levofloxacin. In contrast, after oral administration, the plasma concentration in the portal vein was constantly higher than that in the jugular vein, demonstrating that this difference was caused by the intestinal absorption of levofloxacin.

CONCLUSIONS

Approximately 90% levofloxacin was absorbed as the intact form from the intestinal tract into the portal system. By considering the bioavailability of levofloxacin in rat, the hepatic extraction ratio in vivo of levofloxacin was estimated to be 30%. The mean local absorption time (Ta) was 1.44 hr which coincided almost with the mean absorption time (MAT).

In vitro susceptibilities of Bordetella pertussis and Bordetella parapertussis to four fluoroquinolones (levofloxacin, d-ofloxacin, ofloxacin, and ciprofloxacin), cefpirome, and meropenem

The in vitro activities of levofloxacin, ofloxacin, d-ofloxacin, ciprofloxacin, cefpirome, and meropenem against 34 clinical isolates each of Bordetella pertussis and Bordetella parapertussis were determined by agar dilution on Mueller-Hinton agar supplemented with 5% horse blood. Levofloxacin was as active as ciprofloxacin against both species (MIC, 0.06 microgram/ml) and more active than ofloxacin and d-ofloxacin. Cefpirome was more active against B. pertussis (MIC, 1.0 microgram/ml) than against B. parapertussis (MIC, > 2 micrograms/ml), while the reverse was true for meropenem (MIC, 2.0 micrograms/ml against B. pertussis and 1.0 microgram/ml against B. parapertussis).

Open-label crossover study to determine pharmacokinetics and penetration of two dose regimens of levofloxacin into inflammatory fluid

Two levofloxacin administration regimens were used for six healthy male volunteers. They received either 500 mg of levofloxacin orally every 12 h for five doses or 500 mg every 24 h for three doses, and then 6 weeks later they received the other course. The concentrations of the drug in plasma, cantharidin-induced inflammatory fluid, and urine were measured with a microbiological assay following administration of the final dose. Mean peak concentrations in plasma of 9.3 and 6.6 micrograms/ml were attained 1.1 and 1.2 h after the 12- and 24-h regimens, respectively. Mean peak concentrations is inflammatory fluid of 6.8 and 4.3 micrograms/ml were attained at 2.3 and 3.7 h, respectively. The average steady-state concentrations were 5.0 and 2.2 micrograms/ml in plasma and 4.7 and 2.3 micrograms/ml in inflammatory fluid, respectively. The mean terminal elimination half-lives for plasma were 7.9 and 8.0 h for the two regimens, respectively, and the same values were noted for inflammatory fluid. The overall penetration into inflammatory fluid ranged from 88 to 101% with the 12-h regimen and 83 to 112% with the 24-h regimen. Mean urinary recoveries were 87 and 86% over the corresponding interval of the 12- and 24-h regimens, respectively. These results suggest that administration of levofloxacin once and twice daily should be efficacious for infections caused by the majority of pathogens.

Effects of traditional Chinese medicines on pharmacokinetics of levofloxacin

The effects of single coadministrations of one of three traditional Chinese medicines, Hotyu-ekki-to, Rikkunshi-to, and Juzen-taiho-to, on the pharmacokinetics of levofloxacin (LVFX) were investigated with eight healthy volunteers in an open, random crossover fashion. Subjects each received a single oral dose of LVFX (200 mg) alone and then with a single coadministration of each Chinese medicine. There were no significant differences in any pharmacokinetic parameters of LVFX between the groups. Also, no significant changes in the urinary recovery (> 80%) and renal clearance of LVFX were observed. These results indicate that the Chinese medicines tested have no significant effect on the rate and extent of bioavailability or renal excretion of LVFX.