Xywav for Idiopathic Hypersomnia Receives Priority Review and sNDA Acceptance

In a news release from April 2021, biopharmaceutical company Jazz Pharmaceuticals, Inc. (“Jazz”) shared that the FDA accepted its supplemental New Drug Application (sNDA) for review in relation to Xywav, an orally-administered treatment for patients with idiopathic hypersomnia. Alongside this acceptance, Xywav also received Priority Review status.


Also known as JZP-258, Xywav is an oral oxybate lower-sodium solution. Although the drug is still considered investigational in relation to idiopathic hypersomnia, Xywav is approved for the treatment of narcolepsy, cataplexy, and excessive daytime sleepiness in patients aged 7 or older. In the past, Xywav received Fast Track designation from the FDA.

Its current sNDA and Priority Review status hinge on data from a Phase 3 clinical trial evaluating the safety, efficacy, and tolerability of Xywav in adult patients with idiopathic hypersomnia. The results were recently shared during the 2021 AAN Annual Meeting. Ultimately, Xywav significantly improved idiopathic hypersomnia symptoms and patient quality of life (QOL).

While Xywav was relatively safe and well-tolerated, some associated side effects do exist. These include:

  • Headache
  • Nausea and vomiting
  • Bedwetting (in children)
  • Unintended weight loss
  • Appetite loss
  • Anxiety
  • Dizziness
  • Diarrhea
  • Hyperhidrosis (excessive sweating)
  • Parasomnia

If you or someone you know is taking Xywav and experiences any of the following serious side effects, please visit a doctor immediately:

  • Difficulty breathing
    • Note: This may include slowed breathing or sleep apnea.
  • Low blood pressure
  • Fainting
  • Excessive drowsiness
  • Sleepwalking
  • Mental health changes
    • Note: This may include depression and anxiety, self-harming behavior, unusual or disturbing thoughts, or hallucinations.
  • Coma

Idiopathic Hypersomnia

Unlike narcolepsy or cataplexy, doctors do not know the cause of idiopathic hypersomnia, a rare sleep disorder. In fact, that is even in the name: “idiopathic” means without a known cause. However, researchers are currently attempting to determine what causes this excessive daytime sleepiness. Currently, the condition is thought to have a neurological cause. Because of this, idiopathic hypersomnia is considered primary hypersomnia, meaning it occurs without any other medical problems. This sometimes debilitating disorder prevents people from feeling refreshed, even after a long night’s sleep. Thus, patients may have difficulty completing or participating in everyday tasks. Typically, symptom onset occurs when patients are teenagers or young adults. Symptoms include:

  • Anxiety or depression
  • Irritability
  • Chronic excessive daytime sleepiness
  • Restlessness
  • Appetite loss
  • Sleeping for 9+ hours
  • “Sleep drunkenness,” characterized by confusion, the need for long naps, and difficulty waking
  • Random and immediate need for sleep

Learn more about idiopathic hypersomnia.

Jessica Lynn

Jessica Lynn

Jessica Lynn has an educational background in writing and marketing. She firmly believes in the power of writing in amplifying voices, and looks forward to doing so for the rare disease community.

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