Pfizer Inc. (NYSE: PFE) today announced top-line results for a Phase 3 study that showed Lyrica ® (pregabalin) Capsules CV were as effective as levetiracetam as an adjunctive therapy in adult epilepsy patients experiencing refractory partial onset seizures. The top-line results indicate that the study met its primary endpoint by demonstrating that a comparable proportion of patients on Lyrica achieved at least a 50 percent reduction in the 28-day seizure rate during the maintenance phase relative to levetiracetam. The adverse event profile in the study was consistent with that known for Lyrica. Epilepsy is a chronic disorder in which seizures occur intermittently. Partial onset seizures (simple, complex, and secondarily generalized tonic-clonic) are the most common, particularly in adults, and often require more than one antiepileptic medication. Patients with refractory partial onset seizures are those patients whose seizures are not completely controlled by medical treatment. About the Study The study was a randomized, double-blind, parallel-group, multicenter, comparative, flexible-dose study to compare Lyrica (300, 450, 600 mg/day) to levetiracetam (1,000, 2,000, 3,000 mg/day) in reducing partial onset seizure frequency in subjects with epilepsy. Subjects included in the study were diagnosed with epilepsy with partial onset seizures for at least two years, and were unresponsive to treatment with at least two but no more than five prior antiepileptic drugs (AEDs) and, at the time of the study enrollment, were on stable dosages of one or two standard AEDs. The primary efficacy endpoint was the responder rate, defined as the proportion of subjects who had at least a 50 percent reduction in the 28 day seizure rate (all partial seizures) during the 12-week maintenance phase, as measured from the 6-week baseline. The most common adverse events reported in Lyrica-treated patients were headache, dizziness, insomnia, somnolence, nausea and fatigue. The most common adverse events reported for levetiracetam treated patients were somnolence, dizziness and headache.