Harmony Biosciences Holdings, Inc. announced that the U.S. Food and Drug Administration (FDA) has accepted an Investigational New Drug (IND) application for pitolisant for the treatment of idiopathic hypersomnia (IH). Harmony is planning to initiate a Phase 3 clinical trial to evaluate the safety and efficacy of pitolisant in adult patients with IH in the first half of 2022. IH is a rare and chronic neurological disease that is characterized by excessive daytime sleepiness (EDS) despite sufficient or even long sleep time. People living with IH experience significant EDS along with the symptoms of sleep inertia (prolonged difficulty waking up from sleep) and 'brain fog' (impaired cognition, attention, and alertness). Based on insurance claims data, the number of patients diagnosed with IH in the US ranges from 30,000 ? 40,000. Pitolisant is marketed as WAKIX? in the U.S. for the treatment of EDS or cataplexy in adult patients with narcolepsy. Harmony is also evaluating pitolisant for the treatment of EDS and other symptoms in patients with Prader-Willi syndrome, and for the treatment of EDS and other non-muscular symptoms in adult patients with type 1 myotonic dystrophy. About Idiopathic Hypersomnia: Idiopathic Hypersomnia (IH) is a rare and chronic neurological disease that is characterized by excessive daytime sleepiness (EDS) despite sufficient or even long sleep time. EDS in IH cannot be alleviated by naps, longer sleep or more efficient sleep. People living with IH experience significant EDS along with the symptoms of sleep inertia (prolonged difficulty waking up from sleep) and 'brain fog' (impaired cognition, attention, and alertness). The cause of IH is unknown, but it is likely due to alterations in areas of the brain that stabilize states of sleep and wakefulness. IH is one of the central disorders of hypersomnolence and, like narcolepsy, is a debilitating sleep disorder that can result in significant disruption in daily functioning. About WAKIX? (pitolisant) Tablets: WAKIX, a first-in-class medication, is approved by the U.S. Food and Drug Administration for the treatment of excessive daytime sleepiness or cataplexy in adult patients with narcolepsy and has been commercially available in the U.S. since Fourth Quarter 2019. It was granted orphan drug designation for the treatment of narcolepsy in 2010, and breakthrough therapy designation for the treatment of cataplexy in 2018. WAKIX is a selective histamine 3 (H3) receptor antagonist/inverse agonist. The mechanism of action of WAKIX is unclear; however, its efficacy could be mediated through its activity at H3 receptors, thereby increasing the synthesis and release of histamine, a wake promoting neurotransmitter. WAKIX was designed and developed by Bioprojet (France). Harmony has an exclusive license from Bioprojet to develop, manufacture and commercialize pitolisant in the United States.