A Double-blind, Randomized, Placebo Controlled, Two Arm Multi-center Study to Assess the Efficacy and Safety of a Once Nightly Formulation of Sodium Oxybate for Extended-Release Oral Suspension (FT218) for the Treatment of Excessive Daytime Sleepiness and Cataplexy in Subjects with Narcolepsy

1. Male or female subjects 18 years of age or older;2. Willing and able to give written informed consent for study participation.
3. Documented evidence of a diagnosis of NT1 or NT2 as, in part, determined by an overnight PSG and next-day MSLT with 2 or more SOREMPs with mean sleep latency in the pathological range ie, < 8 minutes or meeting the NT1 or the NT2 as defined by the International Classification of Sleep Disorders -3 criteria.;4. Current continuing presence of EDS as defined by subject report for the last 3 months and an ESS > 10;5. For NT1 only, current continuing presence of cataplexy as defined by subject report for the last 3 months;6. Subjects may use concomitant stimulants, but must comply with the following:;a. They must be on a stable dose of stimulants for at least 3 weeks prior to starting the screening process for this study; AND;b. They must use the same stimulant regimen throughout the entire study period, including during screening and post treatment periods;c. They must discontinue all anti cataplexy drugs;7. Female subjects who:;a. Are postmenopausal for at least 1 year before the screening visit;b. Are surgically sterile, OR;c. If of childbearing potential agree to practice at least one highly effective method of contraception, from the time of the signing of informed consent through the last dose of study drug and for 30 days
after dosing stops (1 ovulatory cycle), or complete abstinence during the study if in line with the preferred and usual lifestyle of the subject.;8. Willing and able to comply with all study mandated requirements and procedures for the duration of the clinical study;9. Willing to adhere to all study restrictions including: ;a. Willingness to comply with the requirement to remain in bed for a minimum of 6 hours after taking the study drug;b. Adherence to concomitant drug washout requirements, as applicable, for the duration of the clinical study. ;c. Willing to refrain from operating a car or heavy machinery if determined necessary by the investigator or willingness to refrain from operating a car or heavy machinery for at least 6 hours after taking the nightly dose of FT218;d. Willing to abstain from alcohol for the duration of the clinical study;e. If a smoker, willing to abstain from smoking at night from approximately 9 pm to 7 am for the duration of the clinical study;10. Evidence of adequate support for the duration of the study, including transportation to and from the study site if needed;To be eligible for inclusion, subjects must satisfy all of the following criteria at the Visit 3 dosing visit:;1. Written informed consent obtained during the screening assessment visit;2. Still eligible as per requirements in Protocol Section 8.3.2;3. Compliance with drug washout requirements;4. Compliance in completing the study screening/baseline Sleep and Symptom Daily Diary. Compliance is defined as completing the diary at least 4 times in each of the screening weeks.;5. Confirmation of EDS as defined by all of the following;a. Baseline ESS score > 10 points; AND;b. Baseline MWT mean sleep latency < 11 minutes following baseline PSG and as confirmed by the central scoring laboratory.;6. For NT1 only, current continuing presence of cataplexy as defined by an average of 8 reported cataplexy attacks per week in the screening/baseline Sleep and Symptom Daily Diary;7. Women of childbearing potential must have a negative serum pregnancy test at screening and a negative urine test within 7 days prior to treatment.

Subjects will be excluded from the study if one or more of the following criteria are applicable: ;1. Any prior use of sodium oxybate;2. Current use of sodium valproate;3. Any use of the following prohibited medications for the duration of the
clinical study: (Section 8.4.8.1)
a. Anticonvulsants
b. Clonidine
c. SSRIs and serotonin and norepinephrine re-uptake inhibitors (SNRIs)
d. MAOIs
e. TCAs
f. Sedative Antihistamines
g. Antipsychotics
h. Tramadol
i. Benzodiazepines
j. Barbiturates
k. Alcohol and CNS depressants
l. Gamma hydroxybutyrate (GHB) dehydrogenase inhibitors
m. Topiramate
n. Opioids
o. Other experimental medications designed to treat narcolepsy, cataplexy or any other condition;4. Treatment with any investigational products within 3 months before study enrollment;5. Any drug known to affect sleep-wake function. Concomitant stimulant use is permitted. ;6. A diagnosis of sleep apnea or any other sleep disorder known to cause EDS as determined by PSG and sleep ;history, including any PSG results indicating an apnea-hypopnea index (AHI) >= 15;7. The presence of any unstable or clinically significant medical and psychiatric disorders (as determined by medical or psychiatric history, physical examination, and/or clinical laboratory test) which in the opinion of the investigator may either put the subject at risk by participation in the study, or may influence the results of the study;8. Subjects with a previous history or current ideation of suicide attempt;9. Subjects who have a history of drug or alcohol use that, in the opinion of the investigator would interfere with study subject safety and adherence to study requirements;10. Required commercial or equivalent driving during the study period;11. An occupation that requires variable shift work or routine night shifts;12. Any travel across more than 3 time zones during the course of the study;13. Consuming more than 14 standard alcoholic drinks per week, on average, before participating in the clinical research study;14. Smoking during the night (approximately between 9 pm and 7 am) during the course of the study;15. Female subjects who are lactating or have a positive pregnancy test. Females of reproductive potential not willing or able to employ at least one highly effective method of contraception to prevent pregnancy for the duration of the study and for 30 days after dosing stops (1 ovulatory
cycle) or complete abstinence during the study if in line with the preferred and usual lifestyle of the stubjects.;16. Any current malignancy and/or any history of malignancy within last 3 years;17. A history of seizure disorder, head trauma, or past invasive intracranial surgery;18. Subjects with severe chronic obstructive pulmonary disease. Subjects with mild to moderate chronic obstructive pulmonary disease and assessed as stable by the principal investigator (PI) are eligible;19. Principal investigator judgement on other underlying respiratory and/or other underlying condition or disorder that would potentiate risk of respiratory or CNS depression with concomitant use of sodium oxybate;20. Known hepatitis B surface antigen-positive status or known or suspected active hepatitis C infection;21. Known human immunodeficiency virus infection or acquired immunodeficiency syndrome related illness;22. Scheduled for procedures requiring general anesthesia during the study;23. Known contraindication/allergy/sensitivity/intolerance to the study drug, sodium oxybate, or the inactive ;ingredients of FT218 or placebo;24. Atrial fibrillation or an abnormal electrocardiogram (ECG) demonstrating clinically significant dysrhythmia(s);25. Recent myocardial infarction or coronary revascularization (less than 3 months);26. Uncontrolled hypertension;27. Known succinic semi-aldehyde dehydrogenase deficiency ;28. Moderately or severely altered blood chemistry as defined by any one of the following:;a. A Cockcroft-Gault calculated creatinine clearance < 60 mL/min; OR ;b. Liver function tests more than twice the upper limit of normal; OR;c. Serum bilirubin more than 1.5 times the upper limit of normal;29. Subjects with a medical diagnosis of major depression as defined by
the DSM-V Criteria for Major Depressive Disorder (MDD).