Population Pharmacokinetics and Pharmacodynamics Modeling to Optimize Dosage Regimen of Levofloxacin

Levofloxacin, a fluoroquinolone antibiotic, is the optical S-(-) isomer of ofloxacin with a broad spectrum of activity. In common with other fluoroquinolones, the main pharmacokinetic/pharmacodynamic (PK/PD) index that correlates with its therapeutic efficacy is the area under the plasma time-concentration curve/the minimum inhibitory concentration ratios.

The aims of the study were to:

1. reveal the population pharmacokinetics, and
2. assess the efficacy of various dosage regimens in achieving the probability of target attainment (PTA) and the cumulative fraction of response (CFR) of levofloxacin when oral levofloxacin was prescribed as the switching therapy after intravenous levofloxacin treatment.

The study was conducted in 45 healthy volunteers. Each subject received one 500 mg tablet of levofloxacin, after which PK studies were carried out, using a Monte Carlo simulation to determine the PTA. By referral to the EUCAST MIC distributions database, the dosage regimens were predicted to achieve CFR greater than or equal to 90%.