The author assessed whole-body clearance and levetiracetam maintenance dose multiplication factor during continuous venovenous hemofiltration in 79-yr-old critically ill patient presented with epilepsy. Medication on admission included carbamazepine, phenytoin, clobazam, and levetiracetam, refractory status epilepticus and abdominal sepsis were diagnosed, requiring ICU admission, for the sepsis, amoxicillin/clavulanic acid, ceftriaxone, and gentamicin were initiated. I.v. propofol and midazolam were started concurrently with continuous electroencephalog. monitoring to ensure a burst suppression pattern. On ICU day 3, anuric renal failure developed, and CVVH was started with an AN69ST hemoflter. To prevent subtherapeutic levetiracetam concentrations, the daily dose was increased from 500 mg 3 times a day to i.v. 1000 mg twice a day, followed by therapeutic drug monitoring. Levetiracetam concentrations were measured at several points in plasma, pre- and postflter, and in ultrafltrate samples using a validated reversed-phase high-pressure liquid chromatog. method. All levetiracetam plasma values except one (41.2 mg/L) were within the therapeutic range of 5-25 mg/L (median, 12.4 mg/L). Mw/Pharm 3.86 was used to calculate the pharmacokinetic parameters: apparent volume of distribution (Vd), 40.5 L; lean body masscorrected Vd, 31 L; pre-CVVH initiation half-life 20 h; post-CVVH half-life, 7.2 h. CLTOTAL was 67.9 mL/min. CLCVVH was 49.6 mL/min, nonrenal clearance was 18.3 mL/min, residual renal clearance was 0 mL/min. The author recommend a levetiracetam dose adjustment of 2000 mg/24 h based on pharmacokinetic simulations, using continuous i.v. dosing in patients receiving continuous venovenous hemofiltration to achieve high target concentrations within the therapeutic range without overdose risk.