The pharmacokinetic characteristics of levetiracetam.

Levetiracetam is the latest in a series of nine new antiepileptic drugs (AEDs) to be licensed for clinical use. Its present license is for use as adjunctive therapy for the treatment of patients with partial seizures with or without secondary generalization that are refractory to other established first line AEDs. Pharmacokinetic studies of levetiracetam have been conducted in healthy volunteers, in patients of all ages with epilepsy, and in certain special populations. Results of these studies indicate that levetiracetam has a very favorable pharmacokinetic profile, characterized by excellent oral absorption and bioavailability (> 95%) and a mean elimination half-life in adults, children and the elderly of 7, 6 and 10.5 h, respectively. Levetiracetam is not bound to plasma proteins and is not metabolized in the liver, so it is not expected to be associated with significant pharmacokinetic interactions. Indeed, to the best of the author's knowledge, no clinically relevant pharmacokinetic interactions with levetiracetam have yet been identified. However, pharmacodynamic interactions with carbamazepine and topiramate have been highlighted. As levetiracetam is primarily excreted unchanged in urine, dosage adjustments are necessary for patients with moderate-to-severe renal impairment. Overall, the pharmacokinetic characteristics of levetiracetam can be considered highly desirable.