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RecruitingNCT04462770ARGUSUpdated Oct 29, 2026

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

A Phase 3 interventional study of Clemizole HCl and Placebo in Dravet Syndrome, sponsored by Epygenix. Recruiting at 86 sites in 11 countries. Open to participants aged 2 Years and older. Per ClinicalTrials.gov, last updated 2026-10-29.

Sponsored by Epygenix · Phase 3, Interventional, and Treatment

From the registry’s dates

  • Started Sep 2020; still recruiting 6 years 1 month later.
Updated Oct 29, 2026First site in ChinaSite recruiting status changed+3 moreGo to Updates ↓
Phase
Phase 3
Study type
Interventional
Enrollment
150
Allocation
Randomized
Ages
2 Years and older
Sex
All
01

Study summary

This is a multicenter, Phase 3, randomized, double-blind, placebo-controlled study designed to evaluate the efficacy and safety of clemizole hydrochloride (EPX-100) as adjunctive therapy in children and adult participants with Dravet syndrome (DS).

Read the detailed description

The study consists of an Observational Phase, a Double-blind Phase consisting of a dose titration and a maintenance period and an optional Open-Label Extension (OLE) Phase.

02

Conditions studied

  • Dravet Syndrome

Keywords

  • Clemizole hydrochloride
  • Convulsive seizure
  • Pediatric epilepsy
  • Dravet syndrome
03

In context

Epilepsies, Myoclonic

92 studies on the registry are indexed under Epilepsies, Myoclonic; 21 are open to participants now.

This study's planned enrollment of 150 is above the median of 31 across 56 interventional studies indexed under Epilepsies, Myoclonic.

Browse Epilepsies, Myoclonic studies →

Lead sponsor

Epygenix is the lead sponsor of 5 studies on the registry; 3 are open to participants now.

Counted across the registry records on this site, refreshed daily.

04

Who can participate

Ages eligible
2 Years and older
Sexes eligible
All
Accepts healthy volunteers
No

Eligibility criteria

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 to provide written and assent (if applicable) prior to initiation of any study related procedures.

  3. Clinical diagnosis of DS. Participants must have seizures which are not completely controlled 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 associated with 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 drug or device \<90 days prior to Screening or plans to participate in another drug or device trial at any time during the study.
  3. Seizures secondary to illicit drug (this includes concomitant use of tetrahydrocannabinol [THC] and nonprescription cannabidiol preparations) or alcohol use, infection, neoplasm, demyelinating disease, degenerative neurological disease, or central nervous system disease deemed progressive, metabolic illness, or progressive 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 prior to Screening.
Terms in these criteria, in plain language(2)

Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.

Informed consent

Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.

You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.

Investigational drug or device

A drug or device being studied in a clinical trial.

It may be new, or already approved and being studied for another use, dose or form. Criteria often leave out people who took part in another study of one within a recent period, commonly 30 days or five half-lives.

05

Study design

Phase
Phase 3
Primary purpose
Treatment
Allocation
Randomized
Intervention model
Parallel assignment
Masking
Triple (Participant, Care provider, Investigator)
Enrollment
150 participants (estimated)

Study arms

  • Experimental
    Double-blind Phase: Clemizole HCl

    Participants will receive clemizole HCl twice a day (BID).

    Drug: Clemizole HCl

  • Placebo comparator
    Double-blind Phase: Placebo

    Participants will receive matching placebo BID.

    Drug: Placebo

  • Experimental
    OLE Phase: Clemizole HCl

    Participants will receive clemizole HCL BID.

    Drug: Clemizole HCl

Interventions

  • DrugClemizole HCl

    Clemizole HCl will be administered as an oral solution.

    Also known as: EPX-100

  • DrugPlacebo

    Flavor- and color-matching placebo will be administered as an oral solution.

06

What researchers measure

Primary outcomes

  1. Percent Change in Countable Motor Seizures Per 28 Days (CMS-28) in the Titration Plus Maintenance Periods Relative to Baseline

    Time frame: From Baseline up to Week 16

  2. European Union: Percent Change in CMS-28 in the Maintenance Period Relative to Baseline

    Time frame: From Baseline up to Week 16

Secondary outcomes

  1. Percentage of Participants with >=50% reduction in CMS-28 Relative to Baseline

    Time frame: From Baseline up to Week 16

  2. Number of Countable Motor Seizure-free Days Relative to Baseline

    Time frame: From Baseline up to Week 16

  3. Clinical Global Impression of Improvement - Clinician (CGII-C) Score

    Time frame: Week 16

  4. Clinical Global Impression of Improvement - Participant/Caregiver (CGII-P) Score

    Time frame: Week 16

  5. Percent Change in All Seizures Relative to Baseline

    Time frame: From Baseline up to Week 16

  6. Incidence of Rescue Anti-epileptic Drug (AED) Use Relative to Baseline

    Time frame: From Baseline up to Week 16

  7. Number of Participants with Treatment-Emergent Adverse Events (TEAEs)

    Time frame: From Baseline up to Week 18

07

Study locations

57 of 86 sites recruiting
08

References and documents

Individual participant data

Plan to share: No

No publications or documents are linked to this record.

09

Timeline

1 registry update since Sep 25, 2026
ElapsedEstimatedEstimated, not yet reachedSimilar studies: half by the dot; the band is the middle halfHalf of similar studies reached it by the dot; the band is the middle half, from a quarter to three quarters

Started Sep 2020 (actual). Primary completion is estimated for Apr 2027, 79 months after the start.

Of 15 phase 3 interventional studies under Epilepsies, Myoclonic, half reached primary completion within 35 months of starting (the median), counting those still running; a quarter within 27 and three quarters within 72. This study's planned 79 months is above that.

How these figures are worked out, and which studies are left out of them.

Registered
Jul 6, 2020
First posted
Jul 8, 2020
StartActual
Sep 15, 2020
Primary completionEst.
Apr 2027
CompletionEst.
May 2029
Last update
Oct 29, 2026
What these dates mean
Start.
When the first participant enrolled; while estimated, when the study expects to open to recruitment.
Primary completion.
When the last participant was examined or treated to collect data for the study's main question, its primary outcome. A study that stopped early gives the date its data collection stopped.
Completion.
When the last participant's last visit took place, for every outcome, secondary ones and side effects included: the end of the study. Often later than primary completion, sometimes the same day.
Actual and Est.
Actual means the registry says the date has happened. Est. (estimated) is a date the sponsor plans or expects. It can still move, and the sponsor is expected to change it to actual once it has passed.
Sites
18 sites added — first site in China. 3 sites changed recruiting status (2 now completed, 1 now recruiting)
Show 3 sites
  • KLES Dr Prabhakar Kore Hospital and Medical Research Centre · Belagavi, IndiaNot yet recruiting→Recruiting
  • Great Ormond Street Hospital For Children · London, United KingdomActive, not recruiting→Completed
  • Sheffield Children's Hospital · Sheffield, United KingdomActive, not recruiting→Completed
Show 18 added (18 China)
  • Beijing Children's Hospital, Capital Medical University - PIN · Beijing, China
  • Peking University First Hospital - Daxing Campus · Beijing, China
  • Children's Hospital of Chongqing Medical University · Chongqing, China
  • The Second Affiliated Hospital of Guangzhou Medical University · Guangzhou, China
  • Shenzhen Children's Hospital · Shenzhen, China
  • The Affiliated Hospital of Guizhou Medical University · Guiyang, China
  • Wuhan Children's Hospital · Wuhan, China
  • Hunan Children's Hospital · Changsha, China
  • Xiangya Hospital Central South University · Changsha, China
  • Xuzhou Children's Hospital · Xuzhou, China
  • Jiangxi Provincial Children's Hospital - Donghu Campus · Nanchang, China
  • The First Hospital of Jilin University · Changchun, China
  • The Second Affiliated Hospital of Xi'an Jiaotong University · Xi'an, China
  • Qilu Hospital of Shandong University · Jinan, China
  • Children's Hospital of Shanghai - Ludinglu Campus · Shanghai, China
  • West China Second University Hospital, Sichuan University - Huaxi Campus · Chengdu, China
  • Chengdu Women's and Children's Central Hospital · Chengdu, China
  • The Children's Hospital Zhejiang University School of Medicine - Hubin Campus · Hangzhou, China
Oct 29, 2026
Interventions
Arm changed Double-blind clemizole HCl→Double-blind Phase: Clemizole HCl; Placebo→Double-blind Phase: Placebo; Open-label clemizole HCl→OLE Phase: Clemizole HCl
Oct 29, 2026
Primary outcomes
1 edited, 1 time frame changed, 1 description edited
What changed in the outcomes
  • EditedEuropean Union: Percent Change in Countable Motor Seizures Per CMS-28 Days in the Maintenance Period Relative to BaselineTime frame: From maintenance period Baseline (Day 29) up to Day 85 → From Baseline up to Week 16
  • Time framePercent Change in Countable Motor Seizures Per 28 Days (CMS-28) in the Titration Plus Maintenance Periods Relative to BaselineFrom Baseline Period (Day 1) up to 16 weeks → From Baseline up to Week 16
  • DescriptionPercent Change in Countable Motor Seizures Per 28 Days (CMS-28) in the Titration Plus Maintenance Periods Relative to Baseline: how it is measured was reworded
Oct 29, 2026
Secondary outcomes
5 edited, 2 time frame changed, 5 removed, 2 description edited
What changed in the outcomes
  • EditedProportionPercentage of Participants with >=50% reduction in Countable Motor Seizures Per CMS-28 Days in the Titration Plus Maintenance Periods Relative to BaselineTime frame: From Baseline Period (Day 1) up to 16 weeks → From Baseline up to Week 16
  • EditedNumber of Countable Motor Seizure-free Days in the Titration Plus Maintenance Periods Relative to BaselineTime frame: From Baseline Period (Day 1) up to 16 weeks → From Baseline up to Week 16
  • EditedPercent Change in All Seizures in the Titration Plus Maintenance Periods Relative to BaselineTime frame: From Baseline Period (Day 1) up to 16 weeks → From Baseline up to Week 16
  • EditedIncidence of Rescue Anti-epileptic Drug (AED) Use in the Titration Plus Maintenance Periods Relative to BaselineTime frame: From Baseline Period (Day 1) up to 16 weeks → From Baseline up to Week 16
  • EditedIncidenceNumber of Participants with Treatment-Emergent Adverse Events (TEAEs)Time frame: From the first dose administration of study drug up to end of the study, approximately up to 172 weeks → From Baseline up to Week 18
  • RemovedEuropean Union: Proportion of Participants with >=50% reduction in Countable Motor Seizures Per 28 Days in the Maintenance Period Relative to BaselineTime frame: From maintenance period Baseline (Day 29) up to Day 85
  • RemovedEuropean Union: Number of Countable Motor Seizure-free Days in the Maintenance Period Relative to BaselineTime frame: From maintenance period Baseline (Day 29) up to Day 85
  • RemovedPercent Change in All Seizures in the Maintenance Period Relative to BaselineTime frame: From maintenance period Baseline (Day 29) up to Day 85
  • RemovedIncidence of Rescue Anti-epileptic Drug Use in the Maintenance Period Relative to BaselineTime frame: From maintenance period Baseline (Day 29) up to Day 85
  • RemovedUnited States FDA: Proportion of Participants with >=50% Reduction in the Countable Motor Seizures Per 28 Days in the Maintenance Period Relative to BaselineTime frame: From maintenance period Baseline (Day 29) up to Day 85
  • Time frameClinical Global Impression of Improvement - Clinician (CGII-C) ScoreDay 85 → Week 16
  • Time frameClinical Global Impression of Improvement - Participant/Caregiver (CGII-P) ScoreDay 85 → Week 16
  • DescriptionClinical Global Impression of Improvement - Clinician (CGII-C) Score: how it is measured was reworded
  • DescriptionClinical Global Impression of Improvement - Participant/Caregiver (CGII-P) Score: how it is measured was reworded
Oct 29, 2026
Show all 1 update
  1. Oct 29, 2026
    18 sites added — first site in China. 3 sites changed recruiting status (2 now completed, 1 now recruiting)
    Show 3 sites
    • KLES Dr Prabhakar Kore Hospital and Medical Research Centre · Belagavi, IndiaNot yet recruiting→Recruiting
    • Great Ormond Street Hospital For Children · London, United KingdomActive, not recruiting→Completed
    • Sheffield Children's Hospital · Sheffield, United KingdomActive, not recruiting→Completed
    Show 18 added (18 China)
    • Beijing Children's Hospital, Capital Medical University - PIN · Beijing, China
    • Peking University First Hospital - Daxing Campus · Beijing, China
    • Children's Hospital of Chongqing Medical University · Chongqing, China
    • The Second Affiliated Hospital of Guangzhou Medical University · Guangzhou, China
    • Shenzhen Children's Hospital · Shenzhen, China
    • The Affiliated Hospital of Guizhou Medical University · Guiyang, China
    • Wuhan Children's Hospital · Wuhan, China
    • Hunan Children's Hospital · Changsha, China
    • Xiangya Hospital Central South University · Changsha, China
    • Xuzhou Children's Hospital · Xuzhou, China
    • Jiangxi Provincial Children's Hospital - Donghu Campus · Nanchang, China
    • The First Hospital of Jilin University · Changchun, China
    • The Second Affiliated Hospital of Xi'an Jiaotong University · Xi'an, China
    • Qilu Hospital of Shandong University · Jinan, China
    • Children's Hospital of Shanghai - Ludinglu Campus · Shanghai, China
    • West China Second University Hospital, Sichuan University - Huaxi Campus · Chengdu, China
    • Chengdu Women's and Children's Central Hospital · Chengdu, China
    • The Children's Hospital Zhejiang University School of Medicine - Hubin Campus · Hangzhou, China
    Primary outcomes 1 edited, 1 time frame changed, 1 description edited
    What changed in the outcomes
    • EditedEuropean Union: Percent Change in Countable Motor Seizures Per CMS-28 Days in the Maintenance Period Relative to BaselineTime frame: From maintenance period Baseline (Day 29) up to Day 85 → From Baseline up to Week 16
    • Time framePercent Change in Countable Motor Seizures Per 28 Days (CMS-28) in the Titration Plus Maintenance Periods Relative to BaselineFrom Baseline Period (Day 1) up to 16 weeks → From Baseline up to Week 16
    • DescriptionPercent Change in Countable Motor Seizures Per 28 Days (CMS-28) in the Titration Plus Maintenance Periods Relative to Baseline: how it is measured was reworded
    Secondary outcomes 5 edited, 2 time frame changed, 5 removed, 2 description edited
    What changed in the outcomes
    • EditedProportionPercentage of Participants with >=50% reduction in Countable Motor Seizures Per CMS-28 Days in the Titration Plus Maintenance Periods Relative to BaselineTime frame: From Baseline Period (Day 1) up to 16 weeks → From Baseline up to Week 16
    • EditedNumber of Countable Motor Seizure-free Days in the Titration Plus Maintenance Periods Relative to BaselineTime frame: From Baseline Period (Day 1) up to 16 weeks → From Baseline up to Week 16
    • EditedPercent Change in All Seizures in the Titration Plus Maintenance Periods Relative to BaselineTime frame: From Baseline Period (Day 1) up to 16 weeks → From Baseline up to Week 16
    • EditedIncidence of Rescue Anti-epileptic Drug (AED) Use in the Titration Plus Maintenance Periods Relative to BaselineTime frame: From Baseline Period (Day 1) up to 16 weeks → From Baseline up to Week 16
    • EditedIncidenceNumber of Participants with Treatment-Emergent Adverse Events (TEAEs)Time frame: From the first dose administration of study drug up to end of the study, approximately up to 172 weeks → From Baseline up to Week 18
    • RemovedEuropean Union: Proportion of Participants with >=50% reduction in Countable Motor Seizures Per 28 Days in the Maintenance Period Relative to BaselineTime frame: From maintenance period Baseline (Day 29) up to Day 85
    • RemovedEuropean Union: Number of Countable Motor Seizure-free Days in the Maintenance Period Relative to BaselineTime frame: From maintenance period Baseline (Day 29) up to Day 85
    • RemovedPercent Change in All Seizures in the Maintenance Period Relative to BaselineTime frame: From maintenance period Baseline (Day 29) up to Day 85
    • RemovedIncidence of Rescue Anti-epileptic Drug Use in the Maintenance Period Relative to BaselineTime frame: From maintenance period Baseline (Day 29) up to Day 85
    • RemovedUnited States FDA: Proportion of Participants with >=50% Reduction in the Countable Motor Seizures Per 28 Days in the Maintenance Period Relative to BaselineTime frame: From maintenance period Baseline (Day 29) up to Day 85
    • Time frameClinical Global Impression of Improvement - Clinician (CGII-C) ScoreDay 85 → Week 16
    • Time frameClinical Global Impression of Improvement - Participant/Caregiver (CGII-P) ScoreDay 85 → Week 16
    • DescriptionClinical Global Impression of Improvement - Clinician (CGII-C) Score: how it is measured was reworded
    • DescriptionClinical Global Impression of Improvement - Participant/Caregiver (CGII-P) Score: how it is measured was reworded
    Interventions Arm changed Double-blind clemizole HCl→Double-blind Phase: Clemizole HCl; Placebo→Double-blind Phase: Placebo; Open-label clemizole HCl→OLE Phase: Clemizole HCl
    + 3 other changes: verification date, description and criteria formatting

From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗

10

Registry details

Key details

Study ID
NCT04462770
Lead sponsor
Epygenix
Collaborators
Harmony Biosciences Management, Inc.
Responsible party
Sponsor
First posted
Jul 8, 2020
Start date
Sep 15, 2020
Primary completion
Apr 2027 (estimated)
Completion
May 2029 (estimated)
Last update
Oct 29, 2026

Study contacts

Krystle Rapchak
Contact
clinicaltrials@harmonybiosciences.com
+1 (312) 847-1289
Eric Bauer
Contact
clinicaltrials@harmonybiosciences.com
Amit Ray, MD
study director · Harmony Biosciences Management, Inc.

Oversight

Data monitoring committee
Yes
FDA-regulated drug
Yes
FDA-regulated device
No
View the source record on ClinicalTrials.gov ↗

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Studies of the drug tested here: Clemizole hydrochloride

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