Inclusion Criteria:

• An IRB/IEC approved written informed consent form signed and dated Male/Female patients age 18 (or 16 years where permitted by law) to 65.

• Minimum body weight of 40 kg. • Patients with a confirmed diagnosis of refractory epilepsy of ≥ 6 months. • Patients must be receiving 1 – 3 concomitant AEDs. • Female patients without childbearing potentials (2 years post-menopausal or surgical sterilization) are eligible. Female patients with childbearing potential are eligible if they use a medically accepted non-hormonal contraceptive method.

Exclusion Criteria:

• Seizures occurring in clusters (seizures occurring either too frequently or indistinctly separated to be reliably counted).

• Status epilepticus within 3 months of Visit 1. • History of non-epileptic seizures. • Patients on vigabatrin. • Patients on felbamate, unless treatment has been continuous for ≥ 18 months. • Use of benzodiazepines (for any indication) taken at a higher frequency than an average of once a week, unless counted as one of the concomitant AEDs.

• Ongoing psychiatric disease other than mild controlled disorders. • Patients with a clinically significant organ dysfunction. • Known allergic reaction or intolerance to pyrrolidine derivatives and/or excipients.

• Pregnant or lactating women. Any woman with childbearing potential who is not using a medically accepted, non-hormonal method of birth control.