[Which factors have an impact on levetiracetam serum concentrations? An analysis in 163 patients with epilepsy].

We evaluated factors possibly influencing serum concentrations of levetiracetam (LEV-SC). The study included 163 patients with epilepsy (91 men, 72 women; mean age 39.6 years). The duration of treatment on first analysis was 226 days; the mean daily dose amounted to 2,434 mg. In each patient between one and seven measurements were carried out (mean 2.2). LEV-SC significantly depended on daily dosage and the interval between the time the medication was taken and the time of blood extraction. A marked drop in LEV-SC was observed 4-5 h following ingestion. Carbamazepine, oxcarbazepine and clobazam reduced LEV-SC, whereas valproate elevated LEV-SC significantly. When assessing evaluation of compliance these factors have to be taken into consideration when comparing intraindividual LEV-SC.