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

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 Dravet syndrome. Participants must have seizures that are notcompletely controlled by AEDs with the following criteria:

• Onset of seizures prior to 18 months of age

• Normal development at onset

• History of seizures that are generalized, unilateral clonic, and/or hemiclonic

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

• Documented mutation of the SCN1A gene.

4. Must be approved to participate by the Independent Reviewer, in collaboration withthe Principal Investigator (PI). Participants will be approved following review ofthe participant's medical and seizure history, historical neuroimaging, historicalEEGs, genetic report confirming SCN1A mutation, and review and classification of atleast 28 days of baseline seizures.

5. ≥4 countable convulsive seizures within minimum 28-day screening/baseline period (e.g., hemiclonic, secondarily generalized tonic-clonic, generalized tonic-clonic,tonic, clonic, tonic/atonic [resulting in a drop], and focal with clear observablemotor signs).

6. Participants should be on a stable regimen of AEDs ≥30 days prior to Visit 1 and ingenerally good health.

7. Participant or parent/ LAR is able and willing to maintain an accurate and completedaily seizure and medication diary for the duration of the trial.

8. Sexually active women of child-bearing potential (WCBP) must be using a medicallyacceptable method of birth control and have a negative serum or urine pregnancy testat the screening (Visit 1) and Randomization (Visit 2). A WCBP is defined as afemale who is biologically capable of becoming pregnant. Medically acceptablemethods of birth control include intrauterine devices in place for at least 3months, surgical sterilization, or adequate barrier methods (e.g., diaphragm andfoam). Use of oral contraceptives in combination with another method (e.g., aspermicidal cream) is acceptable. In participants who are not sexually active,abstinence is an acceptable form of birth control and urine will be tested perprotocol. Women who are of non-child-bearing potential (i.e., post-menopause) musthave this condition captured in their medical history. Pregnant women are excludedfrom this study.

Exclusion Criteria:

The presence of any of the following excludes a participant from the study:

1. Known sensitivity, allergy, or previous exposure to EPX-100 (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 or alcohol use, infection, neoplasm,demyelinating disease, degenerative neurological disease, or central nervous system (CNS) disease deemed progressive, metabolic illness, or progressive degenerativedisease.

4. Concurrent use of drugs known to interfere with EPX-100, including moderate orsevere inducers or inhibitors of CYP3A4/5/7. Specifically, concurrent use ofcarbamazepine, oxcarbazepine and/or phenytoin, as well ingestion of grapefruits andgrapefruit juice, are prohibited.

5. Prior or concurrent use of lorcaserin.

6. Concurrent use of fenfluramine.

7. Has any medical condition that, in the PI's judgment, is considered to be clinicallysignificant and could potentially affect participant safety or study outcome,including but not limited to: clinically significant cardiac disease (includingangina, congestive heart failure, uncontrolled hypertension, and history ofarrhythmias), renal, pulmonary, gastrointestinal, hematologic or hepatic conditions;or a condition that affects the absorption, distribution, metabolism, or excretionof drugs.

8. Has an active suicidal plan/intent or has had active suicidal thoughts in the past 6months or a suicide attempt in the past 3 years.