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Study on Blood Pressure Changes in Narcolepsy Patients Switching from High-Sodium Oxybate to JZP258 (Oxybate Mixed-Salt Formulation)

Verified siteInvestigationalNo placebo
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What is this trial about?

A plain-language summary of the goals, design and what participants do

This clinical trial is focused on studying the effects of switching medications in people with narcolepsy, a sleep disorder that causes excessive daytime sleepiness and sudden sleep attacks. The study involves changing from a high-sodium version of a medication called oxybate to a new formulation known as XYWAV. XYWAV is an oral solution that contains a mix of different salts, including sodium, calcium, magnesium, and potassium oxybate. The purpose of the study is to evaluate how this switch affects blood pressure in participants.

Participants in the study will first be assessed to establish their baseline blood pressure. They will then switch from their current high-sodium oxybate medication to XYWAV. Throughout the study, participants will have their blood pressure monitored regularly to observe any changes. The study aims to understand how the new medication formulation impacts blood pressure over a 24-hour period, including during the day and night.

The study is designed to last for several months, during which participants will continue to take the new medication as directed. The results will help determine if XYWAV is a suitable alternative for managing narcolepsy while potentially offering benefits related to blood pressure management. Participants will be closely monitored by healthcare professionals to ensure their safety and well-being throughout the study.

The research process

The trial runs in 6 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Joining the study

    Upon joining the study, participants are required to have a documented diagnosis of narcolepsy, either Type 1 or Type 2, according to specific medical criteria.

    Participants must be between 18 and 70 years old and have been taking a high-sodium oxybate medication, such as XYREM, at a dose of 6 to 9 grams per night for at least six weeks before the study begins.

  2. Step 2

    Initial assessment

    Participants undergo an initial assessment to measure blood pressure. The average systolic blood pressure (SBP) should be between 130 and 155 mm Hg, and the diastolic blood pressure (DBP) should not exceed 95 mm Hg.

    Blood pressure measurements are taken using a device provided by the study sponsor.

  3. Step 3

    Medication switch

    Participants switch from their current high-sodium oxybate medication to a new medication called XYWAV, which is an oral solution containing sodium oxybate, calcium oxybate, magnesium oxybate, and potassium oxybate.

    The switch aims to evaluate changes in blood pressure over a 24-hour period.

  4. Step 4

    Medication administration

    Participants take the new medication, XYWAV, orally as directed. The dosage and frequency are determined based on the participant's previous medication regimen and medical advice.

  5. Step 5

    Ongoing monitoring

    Throughout the study, participants' blood pressure is monitored regularly to assess any changes from the baseline measurements.

    Participants are required to maintain stable doses of any other medications they are taking, including stimulants, alerting agents, or antihypertensive therapies, unless advised otherwise by their healthcare provider.

  6. Step 6

    End of treatment visit

    At the end of the treatment period, participants attend a final visit to evaluate the change in their 24-hour average systolic blood pressure.

    Additional assessments may include changes in daytime, nighttime, and seated resting blood pressure.

Who can join the trial?

8 criteria

  • Participants must be between 18 and 70 years old when they sign the consent form.
  • Participants need to have a documented diagnosis of narcolepsy, which is a sleep disorder, either Type 1 or Type 2, according to specific medical guidelines.
  • Participants must have been taking a high-sodium oxybate medication, like XYREM, at a dose of 6 to 9 grams per night, with two doses each night, for at least 6 weeks before the study starts.
  • If participants are using stimulants or medications that affect blood pressure, they must have been on the same dose for at least 2 months before the study and agree to continue the same dose during the study.
  • If participants are taking medications for high blood pressure, they must keep the same dose throughout the study unless their doctor advises otherwise.
  • Participants' average systolic blood pressure (SBP), which is the top number in a blood pressure reading, must be between 130 and 155 mm Hg. Participants with difficult-to-control high blood pressure are not eligible.
  • Participants' average diastolic blood pressure (DBP), which is the bottom number in a blood pressure reading, must not be higher than 95 mm Hg. Participants with difficult-to-control high blood pressure are not eligible.
  • Participants can be male or female. Female participants must not be pregnant or breastfeeding. They must either be unable to have children or use a highly effective birth control method during the study and for at least 7 days after the last dose of the study medication. They must also have a negative pregnancy test before starting the study.

Who cannot join the trial?

8 criteria

  • Participants who do not have a diagnosis of narcolepsy. Narcolepsy is a sleep disorder that causes excessive daytime sleepiness and sudden sleep attacks.
  • Participants who are not within the specified age range for the study.
  • Participants who are not able to switch from their current medication to the study medication.
  • Participants who have medical conditions that could interfere with the study or pose a risk to their health.
  • Participants who are pregnant or breastfeeding.
  • Participants who are unable to follow the study procedures or attend study visits.
  • Participants who have a history of substance abuse or dependence.
  • Participants who are currently participating in another clinical trial.
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Investigated drugs

  • High-Sodium Oxybate

    is a medication used to treat narcolepsy, a sleep disorder that causes excessive daytime sleepiness and sudden attacks of sleep. In this trial, participants are switching from this medication to another treatment to evaluate its effects on blood pressure.

  • XYWAV

    is a medication being tested in this trial as an alternative to high-sodium oxybate for people with narcolepsy. The study aims to see how switching to XYWAV affects blood pressure over a 24-hour period.

What is already known about the treatment

XYWAV – XYWAV is administered orally in liquid form, typically taken at night. It is currently recognized in medical literature as a treatment for narcolepsy, particularly for patients who need to switch from high-sodium oxybate. The main therapeutic indication for XYWAV is to manage excessive daytime sleepiness and cataplexy in narcolepsy. At the molecular level, it works by modulating neurotransmitter activity in the brain, although the exact mechanism is not fully understood. XYWAV is classified pharmacologically as a central nervous system depressant.

Investigated diseases

Narcolepsy – Narcolepsy is a chronic sleep disorder characterized by overwhelming daytime drowsiness and sudden attacks of sleep. People with narcolepsy often find it difficult to stay awake for long periods, regardless of the circumstances. This condition can significantly disrupt daily routines. It is often accompanied by cataplexy, which is a sudden loss of muscle tone triggered by strong emotions. Narcolepsy is believed to be caused by a deficiency of a brain chemical called hypocretin, which helps regulate wakefulness. Symptoms typically begin in childhood or adolescence and can persist throughout life.
Trial detailsLast updated 7 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2023-504892-25-00Estimated enrolment121 patientsSponsorJazz Pharmaceuticals PLC

sourced from the EU Clinical Trials Register and site verification

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