Evaluation of the Pharmacokinetics, Safety, and Tolerability of TPM XR as Adjunctive Therapy in Pediatric Subjects With Epilepsy

Inclusion Criteria: 1. Able to provide written IAF, as appropriate, with written informed permission (including ICF where required by regional laws or regulations) from the parent or LAR. 2. Male or female aged 4 to 17 years, inclusive, with a current diagnosis of partial onset or primary generalized epilepsy. 3. Current AED therapy including a stable dose of TPM IR as either adjunctive or monotherapy. All AED therapy (including a Vagal Nerve Stimulator) must have been initiated more than one month prior to Visit 1 and doses must be stable for at least two weeks prior to Visit 1. 4. No diagnosis of a progressive neurological disorder based on previous imaging. 5. Weight within the 25 - 80% weight-for-age percentiles based on the National Center for Health Statistics Growth Charts, and not less than 15.0kg. 6. Able and willing to swallow whole capsules. 7. FOCP should either be sexually inactive for two weeks prior to the first dose and throughout the study or, if sexually active, will be using an effective birth control method. Exclusion Criteria: 1. A documented history of status epilepticus in the past year or seizures secondary to conditions other than epilepsy. 2. Use of either phenytoin or carbamazepine as current AEDs. 3. Diagnosis or an electroencephalogram consistent with a diagnosis of seizure disorders other than partial onset or primary generalized epilepsy. 4. Current diagnosis of Major Depressive Disorder or any history of suicide intent and/or attempt. 5. History or presence of clinically significant, chronic medical condition which, in the opinion of the Investigator, would preclude the subject from entering the study. 6. History of substance abuse or dependence. 7. Females who are pregnant or lactating. 8. Use of an investigational drug or device or participation in an investigational study within 30 days prior to the first dose of SM.