Study objective: To assess the pharmacokinetics of levofloxacin during continuous venovenous hemodiafiltration (CVVHDF) and continuous venovenous hemofiltration (CVVH).
Design: Nonrandomized pharmacokinetic evaluation.
Setting: University surgical intensive care unit.
Patients: Six critically ill patients.
Intervention: Five patients received levofloxacin 500 mg/day and one patient received levofloxacin 125 mg/day All patients received continuous renal replacement therapy: CVVHDF on day 1 and CVVH on day 2, using an acrylonitrile hollow-fiber 0.9-m2 filter, constant blood flow rate of 90 ml/minute, substitution flow rate of 1 L/hour predilution, and dialysate flow rate of 1 L/hour (CVVHDF).
Measurements and main results: Serum, ultrafiltrate, and dialysate concentrations of levofloxacin were determined by high-performance liquid chromatography. Extracorporeal clearance was 26.05 +/- 4.66 ml/hour during CVVHDF and 15.71 +/- 2.73 ml/hour during CVVH (p<0.05). Elimination half-life was 28.08 +/- 4.5 hours and 45.9 +/- 17.7 hours, and distribution volume was 1.51 +/- 0.52 L/kg and 1.42 +/- 0.42 L/kg for CVVHDF and CVVH, respectively. Saturation was 0.76 +/- 0.13 for CVVHDF versus a sieving coefficient of 0.77 +/- 0.16 for CVVH.
Conclusion: Marked extracorporeal elimination of levofloxacin occurs, requiring a dosage adjustment that can be calculated from the characteristics of CVVH and CVVHDF.