Nov 08, 2022

Aculys Pharma initiates a phase 3 clinical study of the histamine H3 receptor antagonist/inverse agonist pitolisant in patients with narcolepsy in Japan

Aculys Pharma, Inc. (“Aculys Pharma” Headquarters: Minato-ku, Tokyo; Representative Director and CEO: Kazunari Tsunaba), a company focused on the development and commercialization of new innovative drugs in the fields of neurology and psychiatry, announced that it has initiated a phase 3 clinical study of the histamine H3 receptor antagonist/inverse agonist pitolisant for the treatment of narcolepsy in Japan.

This phase 3 study consists of a multi-institutional double-blind, randomized, placebo-controlled, parallel group-comparison study (Part 1) and an open-label long-term treatment study (Part 2) to assess the efficacy and safety of pitolisant. Please visit the following site for detailed information on the study.


Pitolisant was developed by Bioprojet. Aculys Pharma has obtained an exclusive license to develop and commercialize it in Japan.

Patients often start suffering from the symptoms of narcolepsy in childhood, adolescence or young adulthood, but aren’t diagnosed to have it until much later due to misdiagnosis, low symptom awareness, or other reasons: The delay in diagnosis is a global challenge.1 The causes and pathophysiology of narcolepsy are largely unknown. In healthy people, neurotransmitters in the brain, such as orexin and histamine, help maintain the regular cycle of daytime wakefulness and nighttime sleep (REM and non-REM sleep), while in patients with narcolepsy, this sleep-wake cycle becomes irregular.2 Due to this irregular sleep-wake cycle, patients with narcolepsy suddenly, and against their will, fall asleep or have difficulty maintaining concentration while engaged in school or work. Some patients also have cataplexy attacks, which are a sudden loss of muscle tone of the whole body or certain voluntary muscles that are triggered by strong emotions, hypnagogic hallucinations (a hallucination that occurs right before falling asleep), and sleep paralysis (“old hag” syndrome). Different patients have different patterns and severity of symptoms, but these symptoms significantly affect the lifestyles of patients, who often face severe challenges in education or employment.3

Aculys Pharma is committed to bringing this drug to patients with narcolepsy in Japan as early as possible and aims to help achieve a society where people with narcolepsy and their family members live their lives to the fullest potential.

About pitolisant

Pitolisant is an antagonist/inverse agonist that selectively binds to the histamine H3 receptor, an autoreceptor located in the presynaptic region of the histamine-containing neurons in the human brain that plays a critical role in regulating sleep and wake rhythm. The drug was created by Paris-based Bioprojet and was approved by the European Medicines Agency (EMA) for the treatment of “narcolepsy with or without cataplexy” in 2016 and for the treatment of “excessive daytime sleepiness associated with obstructive sleep apnea syndrome (OSAS)” in 2021. In the United States, the drug was approved by the Food and Drug Administration (FDA) for the treatment of “excessive daytime sleepiness associated with narcolepsy” in 2019 and “cataplexy associated with narcolepsy” in 2020 and has been available in the clinical setting.

About Aculys Pharma, Inc.

Aculys Pharma is a biopharmaceutical company focused on the development and commercialization of innovations in the fields of neurology and psychiatry. Its corporate name was created from the philosophy of serving as a “Catalyst to Access.” Aiming to act as a bridge for innovative medical care in the field of neuropsychiatry, Aculys Pharma develops and commercializes novel pharmaceuticals and provides innovations for better medical care to patients, their families, healthcare professionals, and society.

Company name: Aculys Pharma, Inc.
Address: 2-14-4 Kitaaoyama, Minato-ku, Tokyo, Japan
Representative: Kazunari Tsunaba
Established: January 2021

Information concerning pharmaceutical products (compound under development) contained herein is not intended as advertising or as medical advice but intended for disclosure of management information.


1 Thorpy MJ, Krieger AC. Delayed diagnosis of narcolepsy: characterization and impact. 2014 May;15(5):502-7.

2 Scammell TE. Narcolepsy. NEJM. 2015;373:2654-2662.

3 Scammell TE, Jackson AC, Franks NP, Wisden W, Dauvilliers Y. Histamine: neural circuits and new medications. Sleep. 2019 Jan 1;42(1):zsy183.