• Ayman M Noreddin, Angela A Reese, Melissa Ostroski, Daryl J Hoban, and George G Zhanel.
• Department of Pharmacy Practice and Pharmaceutical Sciences, College of Pharmacy, University of Minnesota, Duluth, Minnesota 55812, USA. noreddin@umn.edu
• Clin Ther. 2007 Dec 1; 29 (12): 2685-9.

ObjectiveThis study used Monte Carlo simulations to assess the potential for attainment of pharmacodynamic targets with the fluoroquinolones garenoxacin, gemifloxacin, and moxifloxacin against Streptococcus pneumoniae in serum and epithelial lining fluid (ELF) from hospitalized patients with community-acquired pneumonia (CAP).MethodsData on the free AUC over 24 hours (fAUC(0-24)), a measure of drug exposure, were derived from previously described population pharmacokinetic models for therapeutic doses of the 3 fluoroquinolones. MIC distribution data for S pneumoniae were obtained from the Canadian Respiratory Organism Susceptibility Study. These data were used to produce the ratio of fAUC(0-24) to the MIC(90) (fAUC(0-24)/MIC(90)), a pharmacodynamic predictor of bacterial eradication. Monte Carlo simulations were used to analyze the potential for garenoxacin 400 mg QD, gemifloxacin 320 mg QD, and moxifloxacin 400 mg QD to achieve target fAUC(0-24)/MIC(90) ratios of 30, 40, 100, and 120 against S pneumoniae in serum and ELF from hospitalized patients with CAP. Target ratios of 30 and 40 were used to assess the probability of bacterial eradication, while ratios of 100 and 120 were used to assess the probability of preventing development of resistance.ResultsMonte Carlo simulations indicated that all 3 fluoroquinolones had a high probability (>90%) of attaining target fAUC(0-24)/MIC(90) ratios of 30 and 40 against S pneumoniae in both serum and ELF. Garenoxacin 400 mg QD was associated with a >95% probability of achieving target fAUC(0-24)/MIC(90) ratios of 100 and 120 in both serum and ELF. Both gemifloxacin 320 mg QD and moxifloxacin 400 mg QD were associated with high probabilities of attaining fAUC(0-24)/MIC(90) ratios of 100 and 120 in ELF (>95%); the probability of gemifloxacin and moxifloxacin attaining these targets in serum ranged from 78.3% to 88.0%.ConclusionBased on these simulations, garenoxacin 400 mg QD, gemifloxacin 320 mg QD, and moxifloxacin 400 mg QD appeared likely to achieve target serum and ELF concentrations against S pneumoniae in hospitalized patients with CAP, with a low potential to select for resistance.

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