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DOSING OF CIPROFLOXACIN IN UNCOMPLICATED URINARY TRACT INFECTIONS

      Introduction and Background

      Uncomplicated urinary tract (UTI) infections are the commonest bacterial infections in community. Recently ciprofloxacin has become a popular treatment option. However, with increasing resistance to ciprofloxacin, adequacy of current dosing regimens became questionable.

      Methods

      Ciprofloxacin sensitivity was tested on 4 urinary bacterial isolates. Pharmacodynamic parameters (minimum inhibitory concentrations (MIC) and postantibiotic effect) were determined. MIC values were incorporated with ciprofloxacin pharmacokinetic profile using pharmacokinetic/pharmacodynamic efficacy index, Cmax/MIC, which is known to correlate with therapeutic response, in order to compare two dosing regimens of ciprofloxacin: 250mg/12h and 500mg/24h, usually used in treatment of uncomplicated UTI.

      Results

      Urinary concentrations of ciprofloxacin are twice higher after a single 500 mg dose (15, 16) than after a 250 mg one (236 and 518 μg/mL, respectively) and are still high at the end of dosing interval (23 and 32 μg/mL). When PK/PD ratios were calculated, both dosing regimen produced Cmax/MIC values high above the desired threshold of 10 for all tested bacteria and for both dosing regimens, concentrations stay above the MIC (T>MIC) through whole dosing interval. Dosing regimen of 500mg/24h showed supremacy over 250 mg/12h producing higher peak concentrations in urine.

      Conclusion

      The 500mg/24h dose should produce faster eradication rate and slow the development of resistant strains. With the advantage of higher compliance once daily 500mg ciprofloxacin seems better option for treatment of uncomplicated UTI.
      The work is part of Republic project No 41012.