Population Pharmacokinetics of Intravenous Levetiracetam in Neurosurgical Patients: Dosage Optimization Based on CrCl and Mannitol Use
摘要
Conventional low-dose levetiracetam (LEV) for post-neurosurgical seizure prophylaxis often yields subtherapeutic serum levels. This study characterized the population pharmacokinetics (PPK) of intravenous LEV to optimize dosing in neurosurgical patients.
MethodsWe conducted a retrospective PPK analysis in 87 neurosurgical patients (131 concentrations). Nonlinear mixed-effects modeling was used. Monte Carlo simulations identified regimens achieving ≥ 90% probability of target attainment (PTA) for trough concentrations (Cmin) of 12–46 μg/mL.
ResultsLEV median daily dose was 15.4 (7.7–43.5) mg/kg. A median of 1.5 (1–6) concentration samples were collected per patient. The LEV concentrations was 9.11 (1.39–33.79) μg/mL. Importantly, 78 random concentrations and Cmin of 10 patients were all subtherapeutic. Seizures occurred in 13 patients (14.9%); all responded to dose escalation/valproate. A one-compartment model described PK. Estimated clearance (CL) and volume of distribution were 3.73 L/h and 28.10 L, respectively. Covariate analysis identified CrCl and mannitol coadministration as significant CL determinants. Monte Carlo simulations indicated that without mannitol, 1 g q8h (0.5h infusion for CrCl at 20–89 mL/min; 4h infusion for CrCl at 90–129 mL/min) or 1.5 g q8h (0.5h infusion for CrCl at 130–180 mL/min) achieved > 90% PTA. With mannitol, higher doses were required: 1 g q8h (4h infusion, CrCl at 20–49 mL/min) or 1.5 g q8h (0.5h infusion for CrCl at 50–89 mL/min; 4h infusion for CrCl at 90–180 mL/min).
ConclusionStandard LEV prophylaxis dosing often yields inadequate exposure in neurosurgical patients. LEV clearance is influenced by CrCl and mannitol use, higher doses is required for patients with concurrent mannitol therapy.