Clinical pharmacokinetics and pharmacodynamics of gemifloxacin in healthy Chinese volunteers following multiple oral administration / 中华传染病杂志

ABSTRACT

ObjectiveTo investigate the clinical pharmacokinetics (PK) and pharmacodynamics (PD) of gemifloxacin tablet in healthy Chinese volunteers and to provide evidences for optimal clinical dosing.MethodsTwenty volunteers were enrolled in the randomized (1∶1) double-blind study,and divided into administration group and control group.Each group received multiple oral doses of 320 mg of gemifloxacin tablet or placebo.The plasma and urine samples for gemifloxacin were analyzed by igh-performance liquid chromatogram(HPLC)-fluorometricmethod. Theminimuminhibition concentrations (MIC)of gemifloxacin against190clinical isolateswere determinedby broth microdilution method.The fAUC0～24 h/MIC and fCmax/MIC,with target value of 25 and 5,were used as the indices to evaluate PK and PD characteristics of gemifloxacin. The cumulative fraction of response (CFR) of gemifloxacin against each bacterium and the probability of target attainment (PTA) under various MIC level were evaluated using Monte Carlo simulation following multiple administration at steady state.ResultsThe Cmax of gemifloxacin after once-daily oral doses for 7 days were (1.55 ±0.32) μg/mL and (1.57±0.31) μg/mL for the first and last dose,while the AUC0～24 h were (7.91±1.52) and (8.91±1.15) h · μg · mL-1,respectively.The accumulation factor was 1.13±0.05.The time-profile of gemifloxacin could be described using two-compartment model and the half-life of distribution and elimination phase were (0.64 ± 0.17) and (7.10 ± 2.10) h,respectively. The cumulative urinary excretion rates within 24 h of gemifloxacin were 34.83 ％ and 38.95 ％ for the first and the last dose,respectively.PD study showed that the MIC90 of gemifloxacin were 0.25 mg/L and 0.125 mg/L against Streptococcus pneumoniae and Moraxelle catarrhalis,respectively,while the MIC90 was 2 mg/L against Hemophilus influenza. However,most of Klebsiella pneumoniae and methicillin-resistant Staphylococcus aureus (MRSA) were resistant to gemifloxacin ( MIC90 ＞ 32mg/L).The PTA values of fAUC0～24 h/MIC and fCmax/MIC of gemifloxacin 320 mg daily for 7 days were close to 100％ when MIC was ≤0.06 mg/L.ConclusionsGemifloxacin is rapidly absorbed after oral administration of single doses in healthy Chinese volunteers,and the plasma concentration could reach steady state at the third day,while a minimal accumulation is shown after consecutive 7 days dosing.The PK/PD analysis suggests that the favorable clinical and bacteriological efficacy could be obtained when using thisregimen in treatment of sensitive patients with community-acquired pneumonia and acute exacerbation of chronic obstructive pulmonary disease.