The primary objective of this study is to evaluate the effect of Samelisant on excessive daytime sleepiness (EDS) after 12 weeks of treatment. In addition, the study aims to assess its effectiveness in influencing the weekly frequency of cataplexy episodes (sudden bouts of muscle weakness) that occur while the individual remains conscious. Other objectives include examining the impact of Samelisant on attention and alertness, overall quality of life, the spectrum of narcolepsy symptoms, and daily functioning, as well as evaluating its safety profile.
Body mass index ranging from 18 to 45 kg/m2 (both inclusive).
Narcolepsy with or without cataplexy (Narcolepsy Type 1 [NT1] or Narcolepsy Type 2 [NT2]) based on the International Classification of Sleep Disorders 3-TR/ Diagnostic and Statistical Manual of Mental Disorders (DSM-5-TR) criteria for the diagnosis of narcolepsy.
For NT1 only, current continuing presence of cataplexy as defined by participant report for the last 3 months and have average of ≥4 weekly cataplexy events during the last 2 weeks of the washout period.
At the screening Visit and the Baseline Visit, participants who are not on treatment for EDS must have ESS scores ≥12 (as assessed with a look-back period of 1 week).
Median habitual wake-up time after 9 am as assessed by sleep diary, habitual sleep time of <6 h and median habitual bedtime past 1 am, as determined by sleep diary entries.
Use of any investigational therapy within the 30-day period (or 5 half-lives, whichever is longer) prior to enrollment.
History of (within past 3 months) or current substance use disorder involving illicit drugs, alcohol, or marijuana, as per DSM-5-TR criteria. Alcohol and/or recreational drugs use within 24 hours of study visits is strictly prohibited.
Excessive caffeine (defined as >600 mg/day) use at least 1 week prior to Baseline assessments and during the study.