Phase 3 Study of Pitolisant for Excessive Daytime Sleepiness in Narcolepsy Patients

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What is this study about?

narcolepsy is a rare neurological disorder that causes sudden sleep attacks and persistent tiredness during the day. The trial examines the investigational medication HBS-301, given as an oral tablet, and compares it with an inactive tablet (placebo) that looks the same.

The purpose of the study is to evaluate whether the medication can reduce excessive daytime sleepiness in people with the condition. Participants are randomly assigned to receive either the active drug or the placebo during a double‑blind phase, meaning neither the participants nor the study staff know which treatment is being taken. After this period, all participants may enter an open‑label extension where everyone receives the active medication, with regular visits to monitor safety and symptom changes over several months.

1 enrollment

after you agree to join the study you receive a participant number and a copy of the study information.

2 screening

you undergo medical checks to confirm that you have narcolepsy and meet all eligibility criteria for the trial.

3 baseline assessments

your level of excessive daytime sleepiness is measured using the epworth sleepiness scale (ess) questionnaire and the multiple sleep latency test (mwt). these results serve as the starting point for later comparisons.

4 randomization

you are randomly assigned to receive either oral pitolisant tablets or identical placebo tablets. the tablets are round, enteric‑coated and may appear beige to light brown, blue‑green, or blue‑violet depending on the batch, but they look the same to you.

5 titration period

you begin taking one tablet each day. during this period the study team may adjust the amount of medication to reach a target dose; the exact dose and unit are defined by the study protocol and are not disclosed here. the titration continues until the target dose is achieved.

6 double‑blind treatment period

you continue taking the assigned tablet daily while remaining unaware of whether it contains pitolisant or placebo. scheduled visits are held during this period to repeat the ess questionnaire, the mwt, and other safety checks.

7 end of double‑blind period

final assessments are performed at the conclusion of the double‑blind treatment period. these include the ess, the mwt, and additional evaluations to determine any changes in sleepiness and overall safety.

8 open‑label extension

if you choose to continue, you enter an open‑label extension where all participants receive active pitolisant tablets. the same daily dosing schedule is followed and regular follow‑up visits continue to monitor effectiveness and safety.

Who Can Join the Study?

You must be able to give voluntary, written informed consent, meaning you understand the study and sign a document agreeing to participate.
You must have a documented diagnosis of narcolepsy type 1 (NT1) or type 2 (NT2) according to the International Classification of Sleep Disorders (ICSD‑3 or ICSD‑3‑TR), and you must have either a low hypocretin level (a brain chemical that is low in narcolepsy) or a sleep study called polysomnography (PSG) with a multiple sleep latency test (MSLT) performed within the past 10 years.
You must be male or female and at least 18 years old at the time of screening.
You must meet the study’s required clinical criteria, referred to as CCI.
You must meet the study’s required clinical criteria, referred to as CCI.
If you are taking any allowed long‑term medication or supplement (including certain antidepressants or wake‑promoting drugs), the dose must have been stable for at least 3 months before screening and must stay the same during the double‑blind treatment period; you may not use any “as‑needed” (PRN) medicines that could affect daytime sleepiness, such as oxybates, stimulants, modafinil, or armodafinil.
If you are being treated for obstructive sleep apnea (OSA) or other breathing problems during sleep, you must use your prescribed medical device (like a CPAP machine) or oral appliance as instructed and continue using it throughout the study.
If you are a female who could become pregnant, you must have a negative blood (serum) pregnancy test at screening and a negative urine pregnancy test at baseline, and you must agree to avoid pregnancy by staying abstinent or using a highly effective non‑hormonal birth‑control method while taking the study drug and for 30 days after the last dose. If you use hormonal birth control, you must also use a highly effective non‑hormonal method during this time. A female of childbearing potential is defined as someone who has started menstruating, has an intact uterus and at least one ovary, and is less than one year post‑menopause. Male participants who are not sterile (not vasectomized or medically azoospermic) must also agree to abstain or use an effective method of contraception while receiving the study drug and for 30 days after the final dose.
The investigator must believe that you are capable of understanding the study requirements and can follow the instructions for taking the oral study medication.

Who Cannot Join the Study?

You have excessive daytime sleepiness caused by another medical condition (known as hypersomnia).
You have taken the medication pitolisant recently, within the time it takes for the drug to leave your body.
You have participated in another clinical trial that used a new medication, device, or therapy within the past 30 days or until that medication is cleared from your body.
You have a mental‑health condition such as depression that is not stable (symptoms or medicines have not been steady for at least three months).
You have ever been diagnosed with bipolar disorder or psychosis.
You have acute or chronic liver disease, or moderate to severe liver impairment (the liver is the organ that processes medicines and toxins).
Your kidney function test called eGFR (estimated glomerular filtration rate) is below 60 mL/min, indicating reduced kidney performance.
Your screening laboratory tests show one or more results that are considered clinically significant problems.
You have a medical history that raises the risk of dangerous heart rhythm problems (proarrhythmia), such as a recent heart attack, heart failure, or abnormal heart rhythms.
You have a known history of long QT syndrome or a serious abnormality on an electrocardiogram (ECG), such as a recent heart attack (myocardial infarction) or a clinically significant arrhythmia (irregular heartbeat).
You have a family member who died suddenly, died without explanation, or died from a primary heart rhythm problem that may be linked to a prolonged QT interval.
Your corrected QT interval (QTcF) measured on an ECG is greater than 450 milliseconds, which indicates a potential heart rhythm risk.
You currently have, or had within the past year, a substance use disorder (including alcohol or caffeine dependence) as defined by the DSM‑V.
You have surgery planned during the screening, baseline, or double‑blind treatment periods of the study.
You have taken any prohibited medication within five half‑lives before screening. Prohibited drugs include strong CYP3A4 inducers, centrally acting H1‑receptor antagonists, non‑benzodiazepine sleep medicines, and medicines that lengthen the QT interval.
You have taken a medication “as needed” (PRN) that could affect daytime sleepiness—such as oxybates, stimulants, modafinil, or armodafinil—within five half‑lives before screening.
Your urine drug test is positive for substances that are not prescribed by a healthcare professional for a medical condition.
You are considered at significant risk for suicide based on your history, a psychiatric evaluation, the investigator’s judgment, or a positive response to suicide‑related questions, or you have had any suicidal behavior in the past 12 months.
You have a history of seizures (episodes of uncontrolled electrical activity in the brain).
You are currently breastfeeding or plan to breastfeed during the study period.
The investigator judges you unsuitable for the study because of unstable or uncontrolled medical conditions (including psychiatric, neurological, or gastrointestinal issues), surgeries that could affect drug absorption, or any condition that could pose a health risk or interfere with study results.
You do not have the required national health insurance coverage when local regulations require it.

Where you can join this trial?

Verified and Recommended Sites

No sites found in this category

Verified Sites

Site Name	City	Country	Status
Katholieke Universiteit te Leuven	Leuven	Belgium

Other Sites

Site Name	City	Country
Centre Hospitalier Regional De La Citadelle	Liege	Belgium
Somni bene Institut fuer medizinische Forschung und Schlafmedizin Schwerin GmbH	Schwerin	Germany
Hospital Universitario Hm Puerta Del Sur	Mostoles	Spain
Hkzfcacb Clrplu Dd Bjvtgbuun	Barcelona	Spain
Cczekir Uznlgeizxbmtqpievmmq Bzefto Ktr	Berlin	Germany
Klfusyxm djg Uubugeapvusd Mgzgzcpi Atg	Munich	Germany
Ujbsvwxclz Oy Aapxcyq	Edegem	Belgium
Uptishyrelhq Zourtemwzs Gdtk	Gent	Belgium
Hhncecsh Uwzhctfvjoqrn Da Lw Rhlkyy	Alzira	Spain

Trial status

Country	Status	Recruitment Start
Belgium	Not yet recruiting	01.09.2026
Germany	Not yet recruiting	01.09.2026
Spain	Not yet recruiting	01.09.2026

Trial locations

Investigated Drugs:

Pitolisant

Pitolisant is an oral tablet taken by mouth. It works by blocking a brain chemical that keeps you awake, helping to reduce excessive daytime sleepiness in people with narcolepsy. In this study the medicine is being tested to see how well it improves alertness and safety compared with a placebo.

Narcolepsy – Narcolepsy is a chronic neurological disorder that causes overwhelming daytime sleepiness and sudden attacks of sleep. It often begins in adolescence or early adulthood and may be accompanied by cataplexy, sleep paralysis, and vivid dreams. The condition results from loss of brain cells that produce a chemical called hypocretin, which helps regulate wakefulness. Symptoms typically appear gradually and can become more frequent over time. Episodes of excessive sleepiness may occur multiple times a day and can interfere with daily activities. The core features tend to persist throughout life.

Trial ID:

2025-523821-17-00

Protocol code:

HBS-301-CL-301

Trial Phase:

Therapeutic confirmatory (Phase III)

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Phase 3 Study of Pitolisant for Excessive Daytime Sleepiness in Narcolepsy Patients

What is this study about?

Who Can Join the Study?

Who Cannot Join the Study?