The purpose of this study is to evaluate the safety and preliminary effectiveness of the novel compound RWJ-333369 in patients with partial onset seizures who are currently being treated with 1 or 2 concomitant antiepileptic drugs.

333369EPY2002 is the open-label extension study that follows the double-blind study 333369EPY2001. In an open label study such as 333369EPY2002, both the physician and the patient know the name of the assigned study medication. In a double blind study such as 333369EPY2001, neither the physician nor the patient knows the name of the assigned study medication. Patients who complete the double-blind treatment phase of study 333369EPY2001 will be eligible to enter the open-label extension study during which patients will transition through a blinded period to an open-label period with carisbamate (also referred to as RWJ-333369). RWJ-333369 is a new chemical compound with anticonvulsant activity that is currently under investigation as a treatment for epilepsy. Patients electing to enter the open-label extension phase will be supplied with both open-label carisbamate (RWJ-333369) and blinded study medication for the transition phase. During this transition phase (up to 21 days in length), the patient's dose of double-blind study drug will be gradually reduced and stopped and treatment with open-label RWJ-333369 will be started. Throughout the remainder of the open label extension phase, investigators will be allowed to make further adjustments of the dosage and schedule of carisbamate, including independent adjustment of the morning and evening doses, but a dosage of 1,200 mg/day may not be exceeded and increases in dosage must be in increments of no more than 200 mg/day. Patients who, in the judgment of the investigator, continue to benefit from treatment with RWJ-333369 may continue to receive the drug with follow up clinic visits every 3 months until RWJ 333369 is available by prescription or the program is terminated by the sponsor. Initial dose RWJ-333369 is 1 capsule (250 milligram (mg) taken twice daily. Dosage may be changed at weekly intervals. The maximum permitted dose will be 4 capsules (1000 mg), twice daily during dose titration. Double blind-treatment duration is up to 71 days with the option to continue treatment in an open-label study. Maximum dose in open-label study is 1200 mg/day

Inclusion Criteria:

• In order to enter the open label extension, the patient must have completed Study 333369EPY-2001.

Exclusion Criteria:

• Patients who have seizures that cannot be quantitated accurately
• patients with a history of nonepileptic seizures, serious systemic disease, progressive neurologic disorder, a major psychiatric disorder, status epilepticus in the past 3 months, vagal nerve stimulation discontinuation within the past 3 months
• patients with a history of drug or alcohol abuse within the past 2 years
• patients currently taking felbamate, vigabatrin, or tricyclic antidepressants
• and female patients who are pregnant or nursing.