Open-label, Single Arm, Study Evaluating Tolerability and Efficacy of Lacosamide When Added to Levetiracetam With Withdrawal of Concomitant Sodium Channel Blocking Antiepileptic Drug in Subjects With Uncontrolled Partial-onset Seizures

The main purpose of this study is to evaluate the effectiveness of the study drug lacosamide (200-600 mg/day) when added to a stable dose of levetiracetam (1000-3000 mg/day) with withdrawal of the concomitant sodium channel blocking-antiepileptic drug (AEDs) in subjects not well controlled on their current regimen.