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A study to evaluate the effectiveness and safety of clemizole hydrochloride as an additional treatment for patients with Lennox-Gastaut syndrome

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What is this trial about?

A plain-language summary of the goals, design and what participants do

This study aims to evaluate the efficacy of clemizole hydrochloride compared with a placebo in individuals living with Lennox-Gastaut Syndrome. This condition is a rare type of epilepsy, which is a neurological disorder characterized by recurrent, unprovoked seizures. The research focuses on whether adding the study medication to existing treatments can help manage the symptoms associated with this syndrome.

Participants will be assigned to receive either clemizole hydrochloride in the form of an oral solution or a placebo. The study is designed as a double-blind trial, meaning that neither the participants nor the researchers will know which substance is being administered during the process. The course of the study involves different stages, including a period where the dose is gradually adjusted, followed by a maintenance period where the treatment is continued.

The research process

The trial runs in 2 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Participation in the <b>double-blind period</b>

    You will receive either clemizole hydrochloride, which is an oral solution (liquid medicine taken by mouth), or a placebo, which is a substance that contains no active medicine.

    The double-blind nature of this stage means that neither you nor the medical staff will know which medicine is being administered.

  2. Step 2

    <b>titration</b> and <b>maintenance phase</b>

    This stage consists of two parts: the titration phase, where the dose is adjusted, and the maintenance phase, where the dose is kept steady.

    The goal is to observe the effects of the clemizole hydrochloride or the placebo on seizures (sudden, uncontrolled electrical disturbances in the brain) and disability levels related to lennox-gastaut syndrome.

Who can join the trial?

16 criteria

  • Both males and females who are between 2 and 55 years old at the start of the study can participate.
  • The participant, a parent, or a legal guardian must be willing and able to keep a detailed daily seizure diary, which is a written record of when seizures happen.
  • The participant must be willing and able to take the study drug, which is provided in a suspension (a liquid medicine that must be shaken before use), exactly as instructed.
  • Women who are capable of becoming pregnant must use an approved form of birth control (methods used to prevent pregnancy) and must have a negative pregnancy test during the initial visits.
  • Women who cannot become pregnant due to menopause (the time in life when periods stop) or surgery must have this documented in their medical history.
  • Pregnant women are not allowed to join the study.
  • If the participant follows a ketogenic diet (a special high-fat, low-carbohydrate diet), it must have been used consistently for at least 4 weeks before the study begins and must stay the same during the main part of the study.
  • The participant or their legal representative must provide written informed consent, which means they have been fully told about the study's risks and benefits and agree to participate in writing.
  • A diagnosis of Lennox-Gastaut Syndrome (LGS) is required, which must include evidence of major motor seizures (seizures that cause physical movement), specific patterns on an electroencephalogram (an EEG, which is a test that records electrical activity in the brain), abnormal cognitive development (delays in learning or thinking skills), and the start of seizures by age 11 or younger.
  • The participant must have had a specific number of countable seizures (seizures that can be clearly identified and recorded) every month for the 2 months before the study, including tonic or tonic/atonic seizures (types of seizures involving muscle stiffness or sudden loss of muscle tone).
  • The participant must continue to have a required number of major motor seizures after the first screening visit.
  • A medical expert at The Epilepsy Consortium must review all medical documents, such as neuroimaging (pictures of the brain like MRI or CT scans) and seizure records, to confirm the diagnosis and approve participation.
  • If the participant has a vagus nerve stimulator (a small device implanted in the body that sends electrical pulses to the brain to help control seizures), it must have been implanted at least 6 months ago, the settings must have been stable for 3 months, and the battery must be expected to last through the main study period.
  • The participant must have experienced a lack of seizure control even after trying at least one or more anti-seizure medications (ASMs) at the correct dose for an appropriate amount of time.
  • The participant must be on a stable routine of 4 or fewer anti-seizure medications for at least 30 days before the study begins, with no planned changes to the dose during the study.
  • The participant must be in generally good health.

Who cannot join the trial?

18 criteria

  • You cannot participate if you have a known allergy or have used clemizole HCl before.
  • You cannot participate if your electrocardiogram (ECG), which is a test that records the electrical activity of your heart, shows a QT interval (the time it takes for your heart muscle to recharge between beats) that is longer than 450 milliseconds.
  • You cannot participate if you have a history of long QT syndrome (a condition where the heart's electrical system takes too long to recharge) or any serious arrhythmia (an irregular heartbeat).
  • You cannot participate if a family member has a history of sudden cardiac death (unexplained or unexpected heart failure) or heart rhythm problems related to a long QT interval.
  • You cannot participate if your seizures are caused by illegal drugs, alcohol, infections, tumors, diseases that damage the protective covering of nerves, or changes in the central nervous system.
  • You cannot participate if you have had an episode where you stopped breathing or had no oxygen to the brain (an anoxic episode) that required life-saving help within the last 6 months.
  • You cannot participate if you have changed the dose of your long-term medications in the last 30 days.
  • You cannot participate if you are planning to have epilepsy surgery or if you had this surgery within the last 6 months.
  • You cannot participate if you are taking medications that affect cytochrome P450 (CYP) 3A4, which is a specific enzyme in the body that helps break down many drugs.
  • You cannot participate if you are taking or have previously taken lorcaserin.
  • You cannot participate if you are taking fenfluramine or have taken it in the last 3 months without a heart ultrasound to prove you do not have valvular heart disease (problems with the heart's valves) or pulmonary arterial hypertension (high blood pressure in the lungs) caused by the drug.
  • You cannot participate if you test positive for THC (the main ingredient in marijuana) during your first visit.
  • You cannot participate if you use THC or non-prescription cannabidiol (CBD) products.
  • You cannot participate if you are unwilling to stop eating grapefruits, drinking grapefruit juice, or eating Seville oranges.
  • You cannot participate if you have used other experimental drugs or medical devices in the last 90 days or plan to join another study during this trial.
  • You cannot participate if the doctor decides you are not suitable due to unstable medical conditions, such as uncontrolled mental health or nerve-related issues, that could make the study unsafe or the results inaccurate.
  • You cannot participate if you have a high risk of suicide based on your medical history, a psychiatric exam, or specific screening questions.
  • You cannot participate if you have hepatic impairment, which means your liver is not working properly, unless it is very mild and approved by the medical monitor.
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Investigated drugs

Clemizole is an oral liquid medication being tested to see if it can help reduce seizures in people living with Lennox-Gastaut Syndrome when used alongside their current treatments.

What is already known about the treatment

  • Clemizole Hydrochloride

    This medication is taken as a liquid solution by mouth. It is currently being studied as an extra treatment to help manage seizures in people with a rare brain disorder called Lennox-Gastaut Syndrome. The drug works by blocking certain receptors in the body that trigger allergic reactions and by calming down overactive nerve cells in the brain to reduce seizure activity. It is classified as an antihistamine that also has effects on the nervous system.

  • Clemizole Hydrochloride placebo

    This is an inactive liquid solution taken by mouth that looks and tastes like the actual medicine. It contains no active ingredients and is used in clinical trials to serve as a baseline for comparison. It does not have any therapeutic effects or specific mechanism of action in the body.

Investigated diseases

Lennox-Gastaut Syndrome - This is a rare type of epilepsy that typically begins in early childhood. It is characterized by multiple types of seizures that occur frequently. As the condition progresses, the seizures often become more difficult to control. It can also lead to various forms of cognitive impairment and behavioral challenges.
Trial detailsLast updated 2 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2025-522552-20-00Protocol codeEPX-100-003Estimated enrolment260 patientsSponsorEpygenix Therapeutics Inc.

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