Is levetiracetam different from other antiepileptic drugs? Levetiracetam and its cellular mechanism of action in epilepsy revisited.

Levetiracetam (LEV) is a new antiepileptic drug that is clinically effective in generalized and partial epilepsy syndromes as sole or add-on medication. Nevertheless, its underlying mechanism of action is poorly understood. It has a unique preclinical profile; unlike other antiepileptic drugs (AEDs), it modulates seizure-activity in animal models of chronic epilepsy with no effect in most animal models of acute seizures. Yet it is effective in acute in-vitro 'seizure' models. A possible explanation for these dichotomous findings is that LEV has different mechanisms of actions, whether given acutely or chronically and in 'epileptic' and control tissue. Here we review the general mechanism of action of AEDs, give an updated and critical overview about the experimental findings of LEV's cellular targets (in particular the synaptic vesicular protein SV2A) and ask whether LEV represents a new class of AED.