A research study to find out if people with Primary Generalized Tonic-Clonic Seizures, by taking perampanel in addition to their normal epilepsy medicine(s), have fewer seizures and feel better. Either perampanel (real medicine) or placebo (pretend medicine that looks the same as the real medicine) will be given in addition to ordinary epilepsy medicines. Who gets which is decided randomly. There is an option to continue into the Follow-on (Extension) Phase of the study

INTERVENTION: Product Name: perampanel Product Code: E2007 Pharmaceutical Form: Film‐coated tablet INN or Proposed INN: Perampanel Current Sponsor code: E2007 Concentration unit: mg milligram(s) Concentration type: equal Concentration number: 2‐ Pharmaceutical form of the placebo: Film‐coated tablet Route of administration of the placebo: Oral use Product Name: perampanel Product Code: E2007 Pharmaceutical Form: Film‐coated tablet INN or Proposed INN: Perampanel Current Sponsor code: E2007 Concentration unit: mg milligram(s) Concentration type: equal Concentration number: 4‐ CONDITION: Primary Generalized Tonic‐Clonic Seizures ; MedDRA version: 14.1 Level: HLT Classification code 10018101 Term: Generalised tonic‐clonic seizures System Organ Class: 10029205 ‐ Nervous system disorders Therapeutic area: Diseases [C] ‐ Nervous System Diseases [C10] PRIMARY OUTCOME: Main Objective: To demonstrate the efficacy of adjunctive perampanel therapy, compared to placebo, on primary generalized tonic‐clonic (PGTC) seizures Primary end point(s): • Percent Change in PGTC Seizure Frequency; (Except for the purpose of registration in the European Union (EU), where this endpoint will be the key secondary endpoint); ; • Responder Rate: (For the purpose of EU registration, this endpoint will be the key secondary endpoint or other purposes); A responder is defined as a subject who experiences a = 50% reduction in PGTC seizure frequency. Secondary Objective: To evaluate the safety and tolerability of perampanel in subjects with inadequately controlled PGTC seizures Timepoint(s) of evaluation of this end point: • PGTC seizure frequency per 28 days during treatment: The percent change from baseline will be analyzed over the Titration and Maintenance Periods combined in the Full Analysis Set(FAS). The baseline is defined as seizure frequency per 28 days based on all valid diary data during the Prerandomization Phase.; ; • Responder Rate: In the Maintenance Period relative to baseline in the FAS. ; ; SECONDARY OUTCOME: Secondary end point(s): Other secondary efficacy endpoints will be analyzed as follows:; ; • Percent change in all subtypes of primary generalized seizure frequency ; ; • Responder Rate for all subtypes of primary generalized seizure frequency Timepoint(s) of evaluation of this end point: • Percent change in all subtypes of primary generalized seizure frequency:; Per 28 days in the Titration and Maintenance Periods combined relative to baseline will be analyzed using rank ANCOVA in the FAS; ; • Responder Rate for all subtypes of primary generalized seizure frequency:; Per 28 days in the Maintenance Period relative to baseline will be analyzed based on a CMH test in the FAS. INCLUSION CRITERIA: • Ages 12 years and older (in Germany, greater than or equal to 18 years of age [within the course of the study] at the time of the informed consent; in India, less than 65 years of age) • Clinical diagnosis of PGTC seizures in the setting of idiopathic generalized epilepsy (with or without other subtypes of primary generalized seizures) and experiencing = 3 PGTC seizures during the 8‐week period prior to randomization • Have had a routine electroencephalogram (EEG) up to 5 years prior to or during the Baseline Period with electroencephalographic features consistent with primary generalized epilepsy (also called idiopathic generalized epilepsy); other concomitant anomaly should be explained by adequate past medical history. In the case of a normal historical EEG, EEG should be repeated. In the case of another normal EEG upon repeat, the presence or history of myoclonus or typical absence seizure, or first degree relative with PGTC seizure