A Study to Determine if BHV-7000 is Effective and Safe in Adults With Idiopathic Generalized Epilepsy With Generalized Tonic-clonic Seizures

Inclusion Criteria: * Male and Female participants 18 to 75 years of age at time of consent. * Diagnosis of Idiopathic Generalized Epilepsy at least 6 months prior to the screening visit, defined by 2017 International League Against Epilepsy (ILAE) Classification and based on requirements of Epilepsy Adjudication criteria. 1. Subject has probable GTC seizures in the setting of IGE, meaning GTC seizures and either classic 3-4 Hz generalized spike-wave (GSW) or 4-6 Hz polyspike-wave on EEG and no focal abnormality (asymmetric spike-wave fragment is allowed) AND/OR a clear history of absence seizures or myoclonic jerks 2. Subjects with possible GTC seizures in the setting of IGE, meaning GTC and either Normal EEG OR Generalized epileptiform EEG abnormality with atypical spike-wave and no focal abnormality (asymmetric spike-wave fragment is allowed). * Subject meets the 2009 ILAE definition of drug resistant epilepsy, failure of adequate trials of two tolerated and appropriately chosen and used ASM schedules (whether as monotherapies or in combination) to achieve sustained seizure freedom. * Ability of subject or caregiver to keep accurate seizure diaries * Current treatment with at least 1 to 3 ASMs as part of no more than 4 epilepsy treatments in total (e.g., each ASM is considered 1 treatment. Other epilepsy therapies including devices and diet therapy are allowed; together these other therapies count as 1 treatment). * Accurate history of having at least 3 days with a GTC seizure evenly spread throughout the 16 weeks prior to the screening visit, such that a subject had at least 1 day with a GTC seizure during the first 8 weeks and at least 1 day with a GTC seizure during the second 8 weeks. Exclusion Criteria: * History of status epilepticus (convulsive status epilepticus for \> 5 minutes or focal status epilepticus with impaired conscious for \> 10 minutes) within the last 6 months prior to screening visit that is not consistent with the subject's habitual seizure. * History of repetitive/cluster GTC seizures (where individual seizures cannot be counted) within the last 6 months prior to screening visit, or having repetitive/cluster GTC seizures count during the screening phase. * Any condition that would interfere with and/or confound the interpretation of safety or efficacy data from the study, as judged by the Investigator