Pharmacokinetics of ciprofloxacin in patients with acute renal failure undergoing continuous venovenous haemofiltration: influence of concomitant liver cirrhosis.

To determine an adequate dosage of ciprofloxacin in critically ill medical patients on continuous venovenous haemofiltration, we studied the pharmacokinetics of ciprofloxacin in eight critically ill medical patients with renal failure treated with continuous venovenous haemofiltration using polysulfone membranes. Three of those patients also presented with severe liver dysfunction. For comparison, three patients with approximately normal renal function and two patients with impaired renal function were included. During haemofiltration, plasma concentrations of ciprofloxacin were variable. In all critically ill patients ciprofloxacin elimination was significantly slowed; the mean half-life was similarly prolonged to about 14 h in patients on haemofiltration and those with approximately normal renal function. In critically ill patients with impaired renal function not on haemofiltration, the mean half-life was longest. Ciprofloxacin clearance by haemofiltration was a quarter of the total clearance. Although a unique dose recommendation can hardly be made because of the high variability of pharmacokinetics during haemofiltration, a daily dose of 800 mg (400 mg b.i.d.) in average can be regarded as appropriated for reaching a target plasma concentration of 2 to 3 micrograms/mL (mean concentration). Because the half-life of ciprofloxacin was further prolonged by the presence of liver cirrhosis, the dose should be reduced to 600 mg in patients on haemofiltration with concomitant severe liver dysfunction.