• Adverse events as reported spontaneously by the patient and/or caregiver or observed by the investigator, subject withdrawals due to AEs [ Time Frame: 10 days to up to 6 weeks ] [ Designated as safety issue: Yes ]
  

• Changes in hematology, chemistry and urinalysis; changes in ECGs and vital signs; plasma concentrations of lacosamide [ Time Frame: 10 days to up to 6 weeks ] [ Designated as safety issue: Yes ]
  

A multicenter, open-label trial designed to assess the safety and tolerability of rapid initiation of adjunctive lacosamide via a single iv loading dose (iv lacosamide 200mg, 300mg, or 400mg administered over a 15-minute infusion duration) followed by twice daily oral lacosamide dosing (daily dose equivalent to the iv loading dose) in adults subjects 16 - 60 years of age with partial-onset seizures.

Inclusion Criteria:

• Diagnosis of epilepsy with simple partial seizures and/or complex partial seizures
• stable dose regimen of 1 to 2 marketed AEDs for 28 days prior to screening and duration of trial
• acceptable candidate for venipuncture and iv infusion
• at least 1 partial seizure with motor component per 90 days
• maximum allowed seizure frequency during 28 days prior to screening is 40 partial seizures of any type.

Exclusion Criteria:

• Previous use of lacosamide
• history of primary generalized seizures
• history of status epilepticus within last 12 months; history of cluster seizures during 8 week period prior to screening
• nonepileptic events, including psychogenic seizures that could be confused with seizures
• use of neuroleptics, MOA inhibitors, barbiturates, or narcotic analgesics within 28 days prior to screening
• received any rescue benzodiazepines more than once during the 28 days prior to screening
• concomitant treatment of felbamate or previous felbamate therapy within last 6 months
• prior or concomitant vigabatrin use.