A Study to Evaluate the Efficacy, Safety, and Tolerability of Brivaracetam as Monotherapy in Patients 2 to 25 Years of Age With Childhood Absence Epilepsy or Juvenile Absence Epilepsy

Inclusion Criteria:

• Study participant is 2 to 25 years of age inclusive, at the time of signing theinformed consent. No study participants from 2 to <4 years of age will be includedin Stage 1

• Study participant is diagnosed with either childhood absence epilepsy (CAE) orjuvenile absence epilepsy (JAE) as defined by the International League AgainstEpilepsy (ILAE) criteria

• Study participants 2 to <4 years of age and participants who had onset of absenceseizures at an age younger than 4 years must have a negative glucose transportertype 1 deficiency syndrome (GLUT1DS) genetic test

• Study participant is untreated with antiepileptic drugs (AEDs) or pretreated forabsence seizures with a maximum of 2 historical AEDs, but without AED treatment fora period of at least 5 half-lives of the AED before randomization into this study.The UCB study physician should be consulted if in doubt

• Study participant has electroencephalogram (EEG) evidence of bilateral synchronous,symmetric generalized paroxysmal spike waves (2.5-6 hertz) with normal backgroundactivity and with at least 1 electrographically recorded seizure lasting 3 secondsor more on a 1-hour EEG with hyperventilation (HV) while awake at Visit 1 (V1), oron a historical EEG up to 12 weeks before enrollment

• Study participant has a history of clinically evident absence seizures occurring onat least 3 days per week in the 2 weeks prior to enrollment

• Study participant is without treatment with psychoactive drugs or on a stable dosefor at least 2 weeks prior to randomization

• Study participant has normal neurological examination, head size, development andcognition

• Body weight is ≥9 kg

• Male and female a) A sexually active male study participant must agree to use contraception duringthe treatment period and for at least 2 days, corresponding to the time needed toeliminate study treatment, after the last dose of study treatment and refrain fromdonating sperm during this period b) A female study participant is eligible toparticipate if she is not pregnant, not breastfeeding, and at least 1 of thefollowing conditions applies: The study participant is premenarchial OR A woman ofchildbearing potential (WOCBP) who agrees to follow the contraceptive guidanceduring the treatment period and for at least 2 days after the last dose of studytreatment, corresponding to the time needed to eliminate study treatment

• Study participant provides consent/assent, and the study participant's parent/legalrepresentative/caregiver provides signed informed consent for minor studyparticipants, which includes compliance with the requirements and restrictionslisted in the informed consent form (ICF) and in this protocol

Exclusion Criteria:

• Study participant has a history of nonfebrile seizures other than absence seizures (eg, generalized tonic-clonic seizures or myoclonic seizures)

• Study participant has a history of absence status epilepticus

• Study participant has a history or presence of paroxysmal nonepileptic seizures

• Study participant has a clinically relevant electrocardiogram (ECG) abnormality inthe opinion of the Principal Investigator

• Study participant has hepatic impairment (Child Pugh Score A, B, or C) based on theInvestigator's assessment

• Study participant has a history of major psychiatric disease or any clinicallysignificant medical condition that would preclude appropriate study participation

• Study participant has active suicidal ideation prior to study entry as indicated bya positive response ("Yes") to either Question 4 or Question 5 of theColumbia-Suicide Severity Rating Scale (C-SSRS; for study participants 6 years orolder) or clinical judgement (for study participants younger than 6 years). Thestudy participant should be referred immediately to a Mental Healthcare Professional

• Study participant has a lifetime history of suicide attempt (including an activeattempt, interrupted attempt, or aborted attempt). The study participant should beimmediately evaluated by a Mental Healthcare Professional to address safety concerns

• Study participant with known fructose intolerance or hypersensitivity of any of theingredients in brivaracetam oral solution

• Study participant has end-stage kidney disease requiring dialysis

• Concomitant use of rifampicin/rifampin; prior use must have been stopped at least 2months before randomization

• Concomitant use of strong CYP2C19 inhibitors like fluconazole, fluoxetine andfluvoxamine, prior use must have been stopped at least 1 week before randomization

• Study participant has participated in another study of an investigational medicinalproduct (IMP; and/or an investigational device) within the previous 30 days prior toinformed consent

• Study participant has clinical or EEG findings not consistent with a diagnosis ofchildhood absence epilepsy (CAE) or juvenile absence epilepsy (JAE)