Major considerations in the acceptance and impact of new antiepileptic drugs include their pharmacokinetics and their potential for interaction with other drugs. The pharmacokinetics of levetiracetam, a newly approved add-on antiepileptic agent for partial-onset seizures in adults, has been evaluated in 27 phase I and II studies. Consistent findings in these studies include rapid and complete oral absorption, linear dose kinetics, a minimal degree of protein binding, and predominantly renal excretion. Because of the lack of hepatic metabolism and low protein binding, the risk of interaction with other drugs is considered low.