Key Inclusion Criteria:

1. Male or non-pregnant, non-lactating female, age 12 to 65 years

2. Diagnosis of Dravet syndrome, Lennox-Gastaut syndrome, or other developmental and
epileptic encephalopathy

3. Has a minimum number of seizures per 4-week period while taking 1 to 4 anti-seizure
medications

4. All medications and epilepsy interventions must be stable for 4 weeks before screening
and are expected to remain stable during the study

5. The patient/parent/caregiver is able and willing to attend study visits, complete the
diary and take study drug as instructed

Key Exclusion Criteria:

1. Current or past history of cardiovascular or cerebrovascular disease, such as cardiac
valvulopathy, myocardial infarction, stroke, pulmonary arterial hypertension or
abnormal blood pressure

2. Has glaucoma, renal impairment, liver disease or any other medical condition that
would affect study participation or pose a risk to the subject

3. Current or recent history of moderate or severe depression, anorexia nervosa, bulimia
or at risk of suicidal behavior

4. Currently taking anorectic agents, monoamine oxidase inhibitors; serotonin agonists or
antagonists including fenfluramine, atomoxetine, vortioxetine, or other medications
for weight loss

5. Positive test result on the drug screen, except tetrahydrocannabinol (THC) for
patients taking prescribed cannabidiol

Note: Other protocol defined Inclusion/Exclusion criteria may apply.

Eligibility last updated 1/10/23. Questions regarding updates should be directed to the study team contact.