Phase 3 Study of Adjunctive Ganaxolone in Adults With Drug-resistant Partial Onset Seizures and Open-label Extension

This is a 2-cohort study comprised of 2 phases in each cohort. Phase 1 is a double-blind (DB) phase followed by Phase 2, an open-label phase. Cohort 1 will provide tolerability, safety, and PK information for ganaxolone 1200 milligram per day (mg/day), 1800 mg/day and placebo. Cohort 2 will investigate the efficacy, tolerability and safety of ganaxolone 1800 mg/day compared to placebo. Cohort 1 (N= approximately 50) will enroll into a 67-week study comprised of a 4-week prospective baseline period plus 4 week retrospective baseline followed by two treatment phases: a 9-week randomized DB placebo-controlled treatment phase followed by a 52-week open label treatment phase. Cohort 2 (N=150) will enroll into a 72-week study comprised of a 8-week prospective baseline period followed by two treatment phases: a 14-week randomized DB placebo-controlled treatment phase followed by a 52-week open label treatment phase.