The goal of this clinical trial is to see how NLS-2 (mazindol extended-release) works on symptoms of narcolepsy, including cataplexy and excessive daytime sleepiness.

Approximately 48 participants will take part in the study across the United States.

The study treatment (NLS-2 or placebo) will be administered for 8 weeks. After this treatment period, the participant may have the option to participate in a separate long-term extension study during which all participants will be treated with NLS-2.

This is a Phase 3, double-blind, placebo-controlled, multicenter, randomized, parallel-group clinical trial. The primary goal of this study is to assess the efficacy and safety of NLS-2 (mazindol extended-release) tablets in treating Narcolepsy Type 1. The trial aims to determine the effects of NLS-2 on the improvement of narcolepsy symptoms, including cataplexy frequency and excessive daytime sleepiness.

Participants in this trial will receive either NLS-2 or a placebo for 8 weeks. The treatment assignment will be concealed from both the participant and the investigator throughout the trial (unless there is an urgent medical need).

Approximately 48 patients will be enrolled at multiple clinical sites across the United States. Following the completion of the trial, participants may be given the option to enroll in a separate long-term extension trial where all participants will receive NLS-2 treatment.

Key Inclusion Criteria:

• Adults ≥ 18 years of age at the time of signing the informed consent.
• Documented primary diagnosis of Narcolepsy Type 1 (NT1) according to the International Classification of Sleep Disorders-Third Edition (ICSD-3) criteria.
• Willing and able to safely discontinue all prohibited medications, including medications for the treatment of narcolepsy.
• Body Mass Index (BMI) within the range of 18 - 40 kg/m2 (inclusive).

Key Exclusion Criteria:

• Any other (besides narcolepsy) clinically relevant medical, behavioral, or psychiatric disorder that is associated with excessive daytime sleepiness or cataplexy.
• History of myocardial infarction or significant cardiovascular disease, structural cardiac abnormalities, cardiomyopathy, congestive heart failure, cardiac arrhythmias, coronary artery disease, cerebrovascular disease (transient ischemic attack or stroke), or any other significant cardiac problem.
• History of long QT Syndrome or Torsades de Pointes, or an immediate family history of sudden cardiac death.
• History of pulmonary hypertension and/or valvulopathy.
• History of epilepsy, convulsions, or seizures (excluding early childhood febrile seizures).
• Significant history of head injury or head trauma.
• Recent or active suicidal ideation or behavior
• Current, or within the past year, diagnosis of substance abuse or dependence disorder (SUD) including alcohol abuse.
• Narrow-angle glaucoma.
• Severe renal or hepatic insufficiency.
• Occupation that requires variable or nighttime shift work.