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Chemotherapy. 2011;57(5):402-16. doi: 10.1159/000329520. Epub 2011 Oct 18.

Population pharmacokinetics and penetration into prostatic, seminal, and vaginal fluid for ciprofloxacin, levofloxacin, and their combination.

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Institute for Biomedical and Pharmaceutical Research, Nürnberg-Heroldsberg, Germany.



Our objectives were to assess the pharmacokinetic interaction and body fluid penetration of ciprofloxacin and levofloxacin.


This study was a single-dose open randomized three-way crossover in 15 healthy volunteers receiving 500 mg oral levofloxacin, 500 mg oral ciprofloxacin, or 250 mg levofloxacin and 250 mg ciprofloxacin co-administered. Serum, urine, and body fluid concentrations were determined by high-performance liquid chromatography and analyzed via population pharmacokinetic modeling.


Modeling indicated that ciprofloxacin inhibited the renal reabsorption of levofloxacin. Ciprofloxacin increased the net renal clearance of levofloxacin by 13%, as its estimated affinity for a putative tubular reabsorption transporter was 12-fold higher (Km: 568 μM) compared to levofloxacin (Km: 6,830 μM). Levofloxacin increased the bioavailability of ciprofloxacin by 12% and achieved significantly (p < 0.05) higher concentrations at 3 h in ejaculate, prostatic, seminal, and vaginal fluid compared to ciprofloxacin.


Modeling suggested that ciprofloxacin inhibited the tubular reabsorption of levofloxacin due to a 12-fold higher affinity for a putative tubular reabsorption transporter compared to levofloxacin. This pharmacokinetic interaction was not clinically relevant.

[Indexed for MEDLINE]

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