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 study about?

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.

Who Can Join the Study?

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 Study?

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.

Where you can join this trial?

Verified and Recommended Sites

No sites found in this category

Verified Sites

Site Name	City	Country
Hospital Universitario De Navarra	Pamplona	Spain
Spitalul Clinic De Psihiatrie Prof.Dr.Alexandru Obregia	Bucharest	Romania
Spitalul Clinic de Copii “Dr. Victor Gomoiu”	Bucharest	Romania

Other Sites

Site Name	City	Country
ASST Fatebenefratelli Sacco	Milan	Italy
IRCCS Istituto Giannina Gaslini	Genoa	Italy
Azienda Ospedaliera Universitaria Meyer IRCCS	Florence	Italy
Fondazione Istituto Neurologico Nazionale Casimiro Mondino	Pavia	Italy
Centrum Medyczne Plejady Magdalena Celinska Loewenhoff Michal Zolnowski sp.k.	Cracow	Poland
Clinical Best Solutions Sp. z o.o. S.K.	Lublin	Poland
Centrul National Clinic De Recuperare Neuropsihomotorie Copii Dr. Nicolae Robanescu	Bucharest	Romania
University Of Debrecen	Debrecen	Hungary
Spitalul Clinic De Urgenta Pentru Copii Sfanta Maria Iasi	Iasi	Romania
Neurosphera Sp. z o.o.	Warsaw	Poland
Fakultni Nemocnice Brno	Brno	Czechia
Semmelweis University	Budapest	Hungary
IRCCS Ospedale Policlinico San Martino	Genoa	Italy
Spitalul Universitar De Urgenta Bucuresti	Bucharest	Romania
Istituto Neurologico Mediterraneo Neuromed S.p.A.	Pozzilli	Italy
Uniwersytecki Szpital Kliniczny W Poznaniu	Poznan	Poland
University Of Pecs	Pecs	Hungary
Ospedale Pediatrico Bambino Gesu’	Rome	Italy
Fondazione I.R.C.C.S. Istituto Neurologico Besta	Milan	Italy
Centrum Medyczne Saska Kępa	Warsaw	Poland
Fdlhqfkn nhqwkdqld Mqbup a Hhrhakh	Prague	Czechia
Hzukswyl Dm Lk Smxfh Cgkc I Saoi Pvv	Barcelona	Spain
Ujkbduvdoi Mnftm Gdnqyhy Od Cfqnsymcu	Catanzaro	Italy
Hpxcdjxg Vdnv dqbboctk	Barcelona	Spain
Csanym dh Nuuoyduykz Awsiuonn	Sevilla	Spain
Prsymve Cmknit Wwtdsap sny z ohcn	Wroclaw	Poland

Trial status

Country	Status	Recruitment Start
Czechia	Not yet recruiting	20.05.2026
Hungary	Not yet recruiting	20.05.2026
Italy	Recruiting	20.05.2026
Poland	Recruiting	20.05.2026
Romania	Not yet recruiting	20.05.2026
Spain	Recruiting	20.05.2026

Trial locations

Investigated drugs:

Clemizole Hydrochloride

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.

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 ID:

2025-522552-20-00

Protocol code:

EPX-100-003

NCT ID:

NCT05066217

Trial Phase:

Therapeutic confirmatory (Phase III)

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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

What is this study about?

Who Can Join the Study?

Who Cannot Join the Study?