The primary objective of this study is to evaluate the efficacy, safety, and tolerability of 4 daily doses of RWJ-333369 as adjunctive treatment of refractory partial epilepsy in subjects who are between 18 and 70 years of age, inclusive

Inclusion Criteria:

1. Age 18-70 years old,
2. Diagnosis of epilepsy for at least 1 year,
3. Presenting, on average, at least 3 partial onset seizures per month,
4. Currently treated with a stable dose (i.e., for at least 4 weeks) of no more than 3 anti-epileptic drugs (AEDs),

Exclusion Criteria:

1. Have experienced status epilepticus in the past 3 months,
2. Have any serious diseases,
3. History of major psychiatric disorders within the past 2 years.
4. Have received an experimental drug/device within the past 30 days
5. Are pregnant or breastfeeding.