Male and female patients between 16 and 70 years of age who are diagnosed with epilepsy with partial seizures and are taking up to 3 medications for this medical condition will take part in a research study at approximately 85 different locations in the United States.

The purpose of the study is to evaluate the effectiveness, safety and tolerability of consistent dosages of a study drug (lacosamide [SPM 927]) taken orally twice a day for about five months.

Each patient who qualifies and chooses to participate in the study will receive placebo (inactive drug) or gradually increasing doses of lacosamide up to the target dose of 400mg/day or 600mg/day. The target dose or placebo will be maintained for 12 weeks.

The study clinic visits will include a medical history and physical exam, electrocardiogram (ECG), blood and urine sample collection, and completion of a seizure diary.

Patients who complete the study may enroll in an extension trial and receive active study drug.

Inclusion Criteria:

• Epilepsy with partial seizures

Exclusion Criteria:

• Subject received SPM 927 in a previous trial