Levetiracetam pharmacokinetics in critically ill patients undergoing renal replacement therapy

To determine clearance of levetiracetam in patients requiring continuous renal replacement therapy (CRRT) or sustained low efficiency dialysis (SLED).

Adult patients with acute kidney injury or end stage renal disease requiring either CRRT or SLED and levetiracetam were eligible for inclusion. Simultaneous arterial, venous, and effluent samples for analysis of levetiracetam concentrations were collected every two hours for up to 6-8 h. Levetiracetam clearance (CL) and half-life (t_1/2) were calculated for each modality.

Eight CRRT patients and 4 SLED patients completed the study: 67% male, mean age 50 ± 13 years, and 83% had AKI. Seven CRRT patients received continuous venovenous hemodiafiltration (CVVHDF) [median pre-replacement rate 700 mL/h (range 500-1000), post-replacement rate 500 mL/h (range 200-1000), effluent rate 2500 mL/h (range 1700-3650) and delivered CRRT dose 27 mL/kg/h (range 19-54)] and one patient received CVV hemofiltration (CVVH). The mm mean levetiracetam CL during CVVHDF was 31.2 ± 8.5 mL/min, and the and the mean t_1/2 was 10.4 ± 2.2 h. For the patient requiring CVVH, clearance and t_1/2 were 22.5 mL/min and 9.5 h, respectively. Mean levetiracetam CL during SLED performed at a blood flow rate of 250 mL/min and a dialysate flow rate of 100 mL/min was 74.0 ± 25.3 mL/min and t_1/2 was 4.8 ± 2.3 h.

Levetiracetam clearance was substantial with both modalities under the operating conditions reported. There is the potential for subtherapeutic concentrations with current recommended dosing strategies that account only for kidney function and not these extracorporeal routes of elimination.