Objectives:

The new extended release formulation of ciprofloxacin (Cipro XR) was designed for once daily administration in the treatment of urinary tract infection (UTI). The aim of the study was to compare its plasma and urine concentrations and its pharmacokinetic parameters with those of levofloxacin (LVX).

Methods:

In a randomised crossover study, 12 volunteers (six males, six females) received a single oral dose of 1000 mg of Cipro XR or 500 mg of LVX to assess the concentrations (by high-pressure liquid chromatography) in plasma and the urinary excretion at intervals up to 36 h. The following pharmacokinetic parameters were studied: Cmax, tmax, t1/2, AUC, Cltot, Clren, Vdß, Vdss, maximal urinary concentration (Umax), and urinary excretion (UE).

Results:

Both fluoroquinolones were tolerated well. The mean pharmacokinetic parameters are shown in the table. The median cumulative levels of renal excretion of the administered dose of the parent drug were 43% for ciprofloxacin (range, 14–51%; mean ± SD, 41 ± 10%), and 80% for levofloxacin (range, 74–88%; mean ± SD, 80 ± 5%).

Cmax, AUC and UE were statistically significantly higher in the LVX phase, whereas the other pharmacokinetic indices, except t1/2, were statistically significantly higher in the cipro XR phase.

Conclusions:

After oral administration of Cipro XR 1000 mg and LVX 500 mg Cmax and AUC in plasma were significantly higher in the LVX phase. The renal excretion (in milligram) of cipro XR 1000 mg once daily, however, is equivalent to that of LVX 500 mg and overall comparable urinary concentrations and areas under the urinary concentrations are reached by both drugs. Therefore, it can be assumed that the two doses investigated can be considered equivalent for the treatment of UTI.