At the intensive care unit (ICU) fluoroquinolone antibiotics, like levofloxacin, are frequently used for the treatment of infections.

Adequate blood levels are required for a good efficacy of the antibiotic. Due to the fact that levofloxacin is almost completely eliminated renally, the blood levels for this antibiotic are strongly influenced by the renal function. Therefore, this study aims to evaluate the pharmacokinetics of levofloxacin in patients with hyperfiltration, in comparison with critically ill patients with normal renal function.

Inclusion Criteria:

• Patients hospitalized at the Department Intensive Care Unit who are being treated with levofloxacin I.V. (500mg, twice daily) for an infection.

Exclusion Criteria:

• Younger than 18 years
• No informed consent
• No arterial catheter
• Hematocrit ≤ 21
• Pregnancy and lactation
• Creatinine clearance < 80 ml/min