A Study of EPX-100 (Clemizole Hydrochloride) in Participants With Dravet Syndrome

Key Inclusion Criteria:

1. Male and female participants 2 years and older at time of consent.

2. Participant or parent/legally authorized representative (LAR) willing and able toprovide written informed consent, assent (if applicable) prior to initiation of anystudy related procedures.

3. Clinical diagnosis of DS. Participants must have seizures which are not completelycontrolled by AEDs with the following criteria:

• Onset of seizures prior to 18 months of age,

• Normal development at onset,

• History of at least one type of countable motor seizure (CMS),

• Brain MRI without cortical malformation (not including mild atrophy associatedwith the natural progression of DS),

• Genetic mutation of the SCN1A gene must be documented.

Key Exclusion Criteria:

1. Known sensitivity, allergy, or previous exposure to clemizole HCl.

2. Exposure to any investigational drug or device <90 days prior to screening or plansto participate in another drug or device trial at any time during the study.

3. Seizures secondary to illicit drug (this includes concomitant use oftetrahydrocannabinol [THC] and nonprescription cannabidiol preparations) or alcoholuse, infection, neoplasm, demyelinating disease, degenerative neurological disease,or central nervous system disease deemed progressive, metabolic illness, orprogressive degenerative disease.

4. Concurrent use of lorcaserin. Note: Prior use of lorcaserin is permitted if at least 30 days have passed since the last dose.

5. Concurrent use of fenfluramine.

6. Epilepsy surgery planned during the study or epilepsy surgery within 6 months priorto Screening.