Soft tissue concentrations of ciprofloxacin in obese and lean subjects following weight-adjusted dosing

Int J Obes Relat Metab Disord. 2001 Mar;25(3):354-8. doi: 10.1038/sj.ijo.0801555.


Objective: To investigate whether weight adjusted ciprofloxacin dosing results in comparable target site concentrations in obese and lean subjects.

Design: Comparative study in two populations.

Subjects: Twelve obese subjects (mean weight 122+/-22.6 kg, 28-52 y, male∶female ratio 4∶8) and 12 age- and sex-matched lean controls (mean weight 59+/-8.6 kg).

Methods: Sampling of interstitial space fluid by means of calibrated in vivo microdialysis after a weight-adjusted intravenous bolus dose of 2.85 mg/kg ciprofloxacin. Analysis of drug concentration by high pressure liquid chromatography.

Results: We found significantly higher peak and trough levels of ciprofloxacin in plasma for obese subjects (9.97+/-5.64 and 0.44+/-0.10 microg/ml vs 2.59+/-1.06 and 0.19+/-0.09 microg/ml in lean subjects, P<0.05), while concentration-time curves of interstitial fluid of muscle and subcutaneous fat did not differ between the groups. Tissue penetration, expressed as AUC(tissue)/AUC(plasma) ratio was significantly lower in obese subjects (0.45+/-0.27 vs 0.82+/-0.36, P<0.01).

Conclusion: We conclude that the penetration process into the interstitial space fluid is impaired in obese subjects. Therefore antibiotic doses need not be adjusted for an increase in fat/water ratio. Weight-adjusted dosing based on actual body weight will yield adequate tissue levels for ciprofloxacin.

Publication types

  • Comparative Study

MeSH terms

  • Adult
  • Anti-Infective Agents / administration & dosage
  • Anti-Infective Agents / blood
  • Anti-Infective Agents / pharmacokinetics*
  • Area Under Curve
  • Chromatography, High Pressure Liquid
  • Ciprofloxacin / administration & dosage
  • Ciprofloxacin / blood
  • Ciprofloxacin / pharmacokinetics*
  • Extracellular Space / metabolism*
  • Female
  • Humans
  • Male
  • Middle Aged
  • Obesity / metabolism*


  • Anti-Infective Agents
  • Ciprofloxacin