A Double-Blind, Placebo-Controlled, Dose-Ranging Study to Evaluate the Efficacy, Safety, and Tolerability of RWJ-333369 as Adjunctive Therapy in Subjects With Refractory Partial Seizures (Protocol 333369-EPY-2003 [Double-blind] and Protocol 333369-EPY-2006 [Open-label Extension])

333369EPY2006 is the open-label extension study that follows the double-blind study 333369EPY2003. In an open label study such as 333369EPY2006, both the physician and the patient know the name of the assigned study medication. In a double blind study such as 333369EPY2003, neither the physician nor the patient knows the name of the assigned study medication. Patients who complete the double-blind treatment phase of study 333369EPY2003 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 (approximately 3 weeks 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. After 12 months of participation in the open-label extension study, 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. RWJ-333369 (100, 300, 800, or 1,600 milligrams per day) administered orally in 2 equally divided doses for up to 16 weeks of double-blind treatment followed by the option to continue RWJ-333369 treatment in an open-label study for at least 1 year, then until drug is available or production ceases.