As adjunctive therapy in the treatment of patients with partial onset seizures (POS) who have had an inadequate response or have significant intolerance to at least 2 other less costly anticonvulsant therapies (prior or current use); AND Patients are under the care of a physician experienced in the treatment of epilepsy. Note: Less costly anticonvulsant therapies may include the following: Phenytoin, Carbamazepine, Gabapentin, Lamotrigine, Vigabatrin, Topiramate, etc.