AzTrials
AzTrials

Idiopathic HypersomniaPhase 4NCT05875974

A Study to Investigate the Effect of XYWAV on Sleepiness, Polysomnography, and Functional Outcomes in Participants With Idiopathic Hypersomnia or Narcolepsy

A Phase 4 study testing JZP258 (XYWAV) in people with Idiopathic Hypersomnia and Narcolepsy, run by Jazz Pharmaceuticals at 32 sites in 2 countries.

Completed

Finished. The study has ended and is not enrolling. Results may be posted on the official record.

Official record
Search all trials

Trial summary

This study will assess the safety and efficacy of JZP258 (XYWAV) on sleepiness, polysomnography, and functional outcomes in patients with idiopathic hypersomnia (IH) or narcolepsy. Read more about this study

Who is it for?
Ages 18 to 75 years
Conditions the study is for
Idiopathic Hypersomnia, Narcolepsy
What is being tested?
JZP258 (XYWAV)
Type of treatment
Pill or oral medicine
Could I receive a placebo?
No, everyone receives an active treatment
How many people
199 participants
Where
32 sitesin 2 countries
Study dates
27 Jul 2023to 13 Mar 2025
Phase
Phase 4
Are there results?
Yes, posted in the registrySummary in the doctors' view

Key requirements

Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.

  • Ages 18 to 75 years
  • All sexes
  • No healthy volunteers
  • Adult, Older adult

Who may be able to join

  • Is 18 to 75 years of age (inclusive) at the time of signing the informed consent form (ICF)
  • Has a primary diagnosis of IH meeting International Classification of Sleep Disorders, Third Edition (ICSD-3) criteria or narcolepsy (Type 1 or Type 2) meeting ICSD-3 or Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-V) criteria.
  • If not currently taking oxybate medication, has clinically significant symptoms of Excessive daytime sleepiness (EDS) with an ESS score > 10 at Screening Visit 1. If currently taking oxybate medication, has an ESS score > 10 at the Baseline Visit 2 polysomnography (after washout period). Note: Not applicable for participants entering the Narcolepsy >9-gram cohort (see additional criteria below for the Narcolepsy >9-gram cohort).
  • If currently treated with anticataplectics and/or alerting agents, has been taking the same dosage for at least 1 month prior to Screening Visit 1 and has no current plans to adjust the dosage during the study period. Note: Alerting agents refer to either traditional stimulants (eg, amphetamines, methylphenidates) or wake-promoting agents (eg, modafinil, pitolisant, solriamfetol).
  • Additional Inclusion Criteria for Participants in the Exploratory Narcolepsy >9-Gram Cohort
  • Is on a current treatment regimen including XYWAV at a dosage of 9 grams

Who cannot join

  • Shows evidence of a previous untreated or inadequately treated sleep disorder considered by the investigator to negatively impact the conduct of the study, including sleep-disordered breathing, parasomnias, circadian rhythm sleep disorders, or restless legs syndrome determined by a previous sleep-laboratory diagnosis or interview utilizing modules of the Diagnostic Interview for Sleep Patterns and Disorders.
  • Shows evidence of untreated or inadequately treated sleep-disordered breathing during Baseline Visit 2 polysomnography defined as an Apnea/Hypopnea Index (AHI) > 10, using the US Centers for Medicare and Medicaid Services rules (CMS.gov).
  • Has a history or presence of any unstable or clinically significant medical condition (chronic pain condition that may impact sleep), behavioral or psychiatric disorder (including active suicidal ideation or current or past [within 1 year] major depressive episode), or history or presence of another neurologic disorder or surgical history that might affect the participant's safety and/or interfere with the conduct of the study, in the opinion of the investigator.
  • Has recently taken (ie, within 1 month prior to screening), is taking, or plans to take any of the following:
  • A substance or medication contraindicated with XYWAV use, ie. specifically alcohol and sedative hypnotics
  • A medication with a known drug-drug interaction with XYWAV
Show all 11Show fewer
  • A medication that may have similar EEG effects to XYWAV
  • Medications known to have clinically significant CNS sedative effects
  • Other medications, natural health products, or substances from which the participant experiences clinically significant sedation
  • Additional Exclusion Criterion for Participants in the Exploratory Narcolepsy >9-Gram Cohort
  • Any past or current medical conditions or experience that, in the investigator's clinical judgment, would preclude further increases in the current oxybate medication dosage beyond 9 grams

Trial locations and contacts

32 sites in 2 countries.

32 sites in 2 countries

United States29 sites

  • Abington Neurological Associates, LTD

    Abington, Pennsylvania, 19001

  • NeuroTrials Research, Inc.

    Atlanta, Georgia, 30328

  • FutureSearch Trials of Neurology

    Austin, Texas, 78731

  • Sleep Disorders Center of Alabama

    Birmingham, Alabama, 35213

  • Meris Clinical Research, LLC

    Brandon, Florida, 33511

  • St. Lukes Hospital Medical Center

    Chesterfield, Missouri, 63017

  • CTI Clinical Research Center

    Cincinnati, Ohio, 45212

  • Intrepid Research

    Cincinnati, Ohio, 45245

  • Cleveland Clinic Main Campus - Clinical Research Unit

    Cleveland, Ohio, 44195

  • Bogan Sleep Consultants, LLC

    Columbia, South Carolina, 29201

  • Ohio Sleep Medicine and Neuroscience Institute

    Dublin, Ohio, 43017

  • Clinical Research of Gastonia

    Gastonia, North Carolina, 28054

  • Comprehensive Sleep Medicine Associates

    Houston, Texas, 77030

  • Stern Research Partners, LLC

    Huntersville, North Carolina, 28078

  • Amnova Clinical Research

    Irvine, California, 92604

  • Long Beach Research Institute

    Lakewood, California, 90805

  • Santa Monica Clinical Trials

    Los Angeles, California, 90025

  • PharmaDev Clinical Research Institute, LLC

    Miami, Florida, 33176

  • Neurocare, Inc., dba Neurocare Center for Research

    Newtown, Massachusetts, 02459

  • Stanford School of Medicine

    Redwood City, California, 94063

  • Centricity Research Rincon - DBA IACT Health Southeast Lung Associates Research

    Rincon, Georgia, 31326

  • Sleep Therapy & Research Center

    San Antonio, Texas, 78229

  • TriValley Sleep Center

    San Ramon, California, 94583

  • SDS Clinical Trials, Inc.

    Santa Ana, California, 92705

  • Perseverance Research Center, LLC

    Scottsdale, Arizona, 85253

  • Geisinger Clinic

    Scranton, Pennsylvania, 18510

  • Clinical Neurophysiology Services, P.C.

    Sterling Heights, Michigan, 48314

  • Tricoastal Narcolepsy and Sleep Disorders Center

    Sugar Land, Texas, 77479

  • Florida Hospital for Children

    Winter Park, Florida, 32789

Other trials in United States

Canada3 sites

  • Heritage Medical Research Clinic, University of Calgary

    Calgary, Alberta, T2N 4Z6

  • AMNDX Inc

    Markham, Ontario, L3R 1A3

  • Johda Tishon Inc

    Toronto, Ontario, M5S 3A3

Other trials in Canada

About this study

Official title: A Prospective, Open-Label, Single-Arm, Multicenter Study to Evaluate the Effect of Low-Sodium Oxybate Oral Solution (XYWAV) on Sleepiness, Polysomnography, and Functional Outcomes in Adult Participants Aged 18 to 75 Years With Idiopathic Hypersomnia or Narcolepsy

This study will assess the safety and efficacy of JZP258 (XYWAV) on sleepiness, polysomnography, and functional outcomes in patients with idiopathic hypersomnia (IH) or narcolepsy.

Read the detailed description

This prospective, multicenter, single-arm, open-label interventional study will assess the safety and efficacy of JZP258 on sleepiness, polysomnography measurements (eg, sleep stage transitions, sleep patterns, and sleep quality), daytime and nighttime symptoms, pharmacokinetics (in narcolepsy), and patient-reported outcomes that include subjective sleep quality and quality of life in patients with IH or narcolepsy.

Being tested
JZP258 (XYWAV)
Keywords
Idiopathic Hypersomnia, Narcolepsy, Excessive daytime sleepiness, Polysomnography, JZP258, XYWAV, Oxybate
Medical subject headings
Idiopathic Hypersomnia, Narcolepsy, Disorders of Excessive Somnolence

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

  • JZP258 (XYWAV)Drug

    Narcolepsy Cohort: Initiate dosage per XYWAV label and titrate to effect.

    IH Cohort: Initiate dosage per XYWAV label and titrate to effect.

    Exploratory Narcolepsy >9-Gram Cohort: XYWAV titrated to a dosage of >9 to 12 grams.

Study groups in NCT05875974
Study groupRoleWhat they receive
JZP258ExperimentalParticipants will self-administer an oral dose of JZP258 (XYWAV) as per label and titrate to an optimal dosage for each participant.
Receives: Drug: JZP258 (XYWAV)

What is being measured

The primary outcome is the main question the study is designed to answer.

  1. Change From Baseline in Epworth Sleepiness Scale (ESS) Total Score in Participants With IH and Narcolepsy Treated With XYWAV

    The ESS total score (the sum of 8 item scores, each 0 to 3) can range from 0 to 24. Higher ESS total scores are associated with higher sleep propensity in daily life, also referred to as "daytime sleepiness."

    Measured: Baseline up to End of Treatment (approximately 10-36 weeks)

Secondary outcomes (10)

  1. Change From Baseline in Idiopathic Hypersomnia Severity Scale (IHSS) Total Score in Participants With IH Treated With XYWAV

    The IHSS is a 14-item self-reported instrument that assesses the severity and functional consequences of IH symptoms. Questions capture symptoms of excessive sleepiness, sleep inertia, and long sleep duration. IHSS total scores range from 0 to 50 with higher score indicating worse clinical outcome.

    Measured: Baseline up to End of Treatment (approximately 10-21 weeks)

  2. Change From Baseline in Number of Stage Shifts of Sleep in Participants With Narcolepsy Treated With XYWAV

    Stage shifts of sleep are defined as the count of transitions of bouts of sleep from deeper to lighter stages of sleep/wake (ie from N3/N2/N1/REM to wake and from N3/N2/REM to N1).

    Measured: Baseline up to End of Treatment (approximately 10-36 weeks)

  3. Change From Baseline in Duration of Sleep Stages in Participants With Narcolepsy Treated With XYWAV

    Duration of sleep stages is measured in minutes (ie N1/N2/N3/REM) and is recorded from sleep onset to awakening during the nocturnal polysomnograph.

    Measured: Baseline up to End of Treatment (approximately 10-36 weeks)

  4. Change From Baseline in Number of Nocturnal Awakenings and Nocturnal Arousals in Participants With Narcolepsy Treated With XYWAV

    Measured: Baseline up to End of Treatment (approximately 10-36 weeks)

  5. Change From Baseline in Percentage of Sleep Stages in Participants With Narcolepsy Treated With XYWAV

    The percentage of sleep stages is measured as minutes of each sleep stage (N3/N2/N1/REM) per hour of sleep time from sleep onset to awakening in the nocturnal polysomnograph.

    Measured: Baseline up to End of Treatment (approximately 10-36 weeks)

  6. Patient Global Impression of Change (PGI-C) in Participants With IH and Narcolepsy Treated With XYWAV (Overall, Sleep Inertia, and Fatigue)

    The PGI-C is a single-item 7-point, Likert-type scale for rating change in disease or symptom severity. Responses for each question ranged from 1 (very much improved) to 7 (very much worse) relative to baseline. Participants rated the change from baseline in their overall (IH or narcolepsy) symptoms, sleep inertia (difficulty waking in the morning), and fatigue (extreme tiredness resulting from mental or physical exertion).

    Measured: End of Treatment (approximately 10-36 weeks)

  7. Level of Rested or Refreshed Upon Awakening in Participants With IH and Narcolepsy Treated With XYWAV (Sleep Diary)

    The participant was asked "How rested or refreshed did you feel when you woke up for the day?"

    Measured: Baseline up to End of Treatment (approximately 10-36 weeks)

  8. Patient Global Impression of Severity (PGI-S) Score in Participants With IH and Narcolepsy Treated With XYWAV (Overall, Sleep Inertia, and Fatigue)

    The PGI-S is a single-item, 7-point, Likert-type scale for rating disease or symptom severity. Responses ranged from 0 (not present) to 7 (extremely severe). Participants rated the severity of their overall (IH or narcolepsy) symptoms, sleep inertia, and fatigue. Higher scores indicate worse clinical outcome.

    Measured: Baseline up to End of Treatment (approximately 10-36 weeks)

  9. Pharmacokinetic Parameter Maximum Plasma Concentration (Cmax) In a Subset of Participants With Narcolepsy Treated With XYWAV

    Blood samples were processed to obtain plasma samples and then analyzed for oxybate concentrations using a validated bioanalytical method.

    Measured: PK: Predose, 0.5 hour, 0.75 hour, 1 hour, 1.5 hour post-first dose and post-second dose, 6 hour post-first dose, 8 hour post-first dose

  10. Pharmacokinetic Parameter Area Under the Concentration-Time Curve From Time 0 to Infinity (AUC0-inf) In a Subset of Participants With Narcolepsy Treated With XYWAV

    Blood samples were processed to obtain plasma samples and then analyzed for oxybate concentrations using a validated bioanalytical method.

    Measured: PK: Predose, 0.5 hour, 0.75 hour, 1 hour, 1.5 hour post-first dose and post-second dose, 6 hour post-first dose, 8 hour post-first dose

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

  1. First posted25 May 2023
  2. Study start27 Jul 2023
  3. Primary completion13 Mar 2025
  4. Study completion13 Mar 2025

Resources

More details

For doctors and researchers: how the study is designed, who runs it, and its registry IDs.

Study design
Study type
Interventional
Phase
Phase 4
Primary purpose
Treatment
Allocation
Not applicable
Intervention model
Single group
Masking
None (open label)
Enrolment
199 participants (actual)
IDs, dates and publications
ClinicalTrials.gov ID
NCT05875974
Sponsor's protocol ID
JZP258-407
Status last verified
Aug 2026
First submitted
16 May 2023
Last updated
27 Aug 2026
Data monitoring committee
No
FDA-regulated drug
Yes
FDA-regulated device
No
Individual data sharing
No

Publications

  • Simmons JH, Schneider LD, Ruoff CM, Plante DT, Nichols DA, Steininger TL, Whalen M, Kirby MT, Dai J, Cairns A, Bogan RK. Symptom improvement with dosing above 9 g of low-sodium oxybate: effectiveness and safety in participants with narcolepsy in the DUET study. J Clin Sleep Med. 2026 Oct 15;22(1):198. doi: 10.1007/s44470-026-00193-6.

    PubMed 42881322

  • Schneider LD, Ruoff CM, Plante DT, Nichols DA, Steininger TL, Fuller DS, Kirby MT, Akerman S, Alexander JK, Whalen M, Cairns A. Effectiveness and Safety of Low-Sodium Oxybate in Participants with Narcolepsy: Primary Results from the DUET Study. Neurol Ther. 2026 Aug;15(4):1613-1641. doi: 10.1007/s40120-026-00921-3. Epub 2026 Apr 30.

    PubMed 42060037

  • Plante DT, Cairns A, Schneider LD, Nichols DA, Steininger TL, Fuller DS, Kirby MT, Akerman S, Alexander JK, Whalen M, Ruoff CM. Effectiveness and Safety of Low-Sodium Oxybate in Participants with Idiopathic Hypersomnia: Primary Results from the DUET Study. CNS Drugs. 2026 Jun;40(6):803-822. doi: 10.1007/s40263-025-01262-9. Epub 2026 Mar 14.

    PubMed 41831073

Questions about this trial

What is this clinical trial studying?

A Phase 4 study testing JZP258 (XYWAV) in people with Idiopathic Hypersomnia and Narcolepsy, run by Jazz Pharmaceuticals at 32 sites in 2 countries.

The full registered description is in the About this study section and the official record.

Who may be eligible to take part?

The sponsor lists 6 inclusion and 11 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.

Is this clinical trial currently recruiting?

The record says: finished, as of the sponsor's last update on 27 Aug 2026. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 32 sites in United States, Canada. Whether a site is taking part right now should be confirmed with that site. See every site.

What are the possible benefits and risks?

They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.

What does this phase mean?

Phase 4 studies take place after a treatment is approved, to learn more about its long-term benefits and risks in everyday use.

Not every study follows the same path, and some studies (observational studies, device studies) have no phase.

Are results available for this study?

Yes. Results are posted in the registry (first posted 27 Aug 2026). A summary is in the For doctors view, and the full results are on ClinicalTrials.gov.

How can a doctor refer a patient or contact the research team?

The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.

What does the primary outcome measure?

Change From Baseline in Epworth Sleepiness Scale (ESS) Total Score in Participants With IH and Narcolepsy Treated With XYWAV (time frame: Baseline up to End of Treatment (approximately 10-36 weeks)). It is what the study was designed to measure, not a finding.

Where can I read the original study information?

On the ClinicalTrials.gov record for NCT05875974, which also lists 3 linked publications.

Does a listing mean the treatment is approved or proven to work?

No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.

How often is this information updated?

AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 27 Aug 2026.

AzTrials uses cookies for analytics and advertising. You can accept or reject them; the site works either way. Privacy Policy.

Free account

Keep searching with a free account

You’ve used your 3 free searches for this session. Log in or create a free AzTrials account to keep searching clinical trials and save the ones you want to follow.

Create a free accountLog in