Effect of renal function on the bioavailability of ciprofloxacin

The effect of renal function on the bioavailability of ciprofloxacin was studied in 21 subjects with measured creatinine clearances ranging from 0 to 8.99 liters/h per 1.73 m2. Each subject received ciprofloxacin, 200 mg intravenously and 750 mg orally, separated by at least 1 week. Serial (12 to 15) blood samples were obtained over 24 to 48 h. Concentrations in serum were assayed by high-pressure liquid chromatography. Area under the curve was calculated by the trapezoidal rule with extrapolation to infinity. Bioavailability was calculated as the ratio between the dose-normalized area under the curve of oral and intravenous administrations. The overall mean (standard deviation) bioavailability observed was 63.4% (14.6%), similar to that observed in those with normal renal function (69.0% [15.7%]). The mean bioavailability in the subgroup of subjects with renal insufficiency was 59.9% (13.3%). The observed range in bioavailability was 33.9 to 91.4%. Linear regression did not reveal a correlation between creatinine clearance and bioavailability. Renal insufficiency does not appear to affect ciprofloxacin bioavailability.