• The percent reduction in seizure frequency (average monthly seizure rate) of complex partial and/or secondarily generalized and/or simple partial motor seizures during the double-blind treatment period, compared with the pretreatment baseline.
  

• The percentage of subjects with >=50% reduction from baseline in seizure frequency; the percent reduction from baseline in secondarily generalized tonic-clonic seizure frequency; and the percentage of subjects who become seizure free.
  

According to the World Health Organization, epilepsy afflicts more than 50 million people worldwide. First generation antiepileptic drugs (AEDs) are still commonly used, despite being associated with a variety of severe adverse events. Newer AEDs have shown an improved tolerability profile, but approximately 30% of patients, particularly those with partial seizures, are not fully responsive to treatment (refractory). RWJ-333369 is a new chemical compound with anticonvulsant activity that is currently under investigation as a treatment for epilepsy.This study will take place in multiple locations and will compare the effectiveness and safety of several different doses of RWJ-333369 versus placebo, as additional treatment in partial epilepsy that is unresponsive (refractory) to other medication. The study is composed of 4 phases: a pretreatment baseline phase of 8 weeks, a double-blind phase of 16 weeks in which patients are randomly assigned to RWJ-333369 or placebo (neither patient nor investigator will know the treatment), a posttreatment phase for patients who do not wish to enter the open-label extension, and the final, optional phase, which is an open-label extension in which eligible patients may continue to receive a known dose of RWJ-333369 until it becomes available or until production of it ceases. Effectiveness will be evaluated based on the number of seizures occurring during the pretreatment and the double-blind treatment phases. The patient diaries will be the source of all seizure count data. The type of seizure recorded will include the following: complex partial and/or secondarily generalized, and/or simple partial motor seizures. The study hypothesis is that RWJ-333369, taken as add-on therapy to treatment with AEDs, will significantly reduce seizure frequency, compared with placebo, in patients with refractory partial epilepsy: that is, in patients who continue to have seizures despite treatment with a first-line AEDs.

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.