Xywav (calcium, magnesium, potassium, and sodium oxybates)

Reviewed by: HU Medical Review Board | Last reviewed: January 2022 | Last updated: December 2022

Xywav® (calcium, magnesium, potassium, and sodium oxybates) is approved by the US Food and Drug Administration (FDA) for the treatment of narcolepsy and idiopathic hypersomnia.1

Xywav is approved for use in people at least 7 years old who have narcolepsy with cataplexy (sudden loss of muscle tone) or excessive daytime sleepiness. It is also approved for adults with idiopathic hypersomnia.1

What are the ingredients in Xywav?

The active ingredients in Xywav include:1

  • Calcium oxybate
  • Magnesium oxybate
  • Potassium oxybate
  • Sodium oxybate (gamma-hydroxybutyrate)

How does Xywav work?

Xywav is a depressant (sedative) of the central nervous system (CNS). The exact way Xywav works to help people with narcolepsy is unknown. The ingredients in Xywav are made by the body when it breaks down GABA (gamma-aminobutyric acid). GABA is a chemical that is made naturally in the brain.1

What are the possible side effects?

The most common side effects of Xywav in adults include:1

  • Headache
  • Dizziness
  • Nausea, vomiting, or decreased appetite
  • Anxiety
  • Heavy sweating
  • Insomnia
  • Dry mouth
  • Parasomnias, such as:
    • Abnormal dreams
    • Abnormal sleep during the rapid eye movement (REM) stage
    • Sleep paralysis
    • Sleep talking
  • Fatigue
  • Tremor

The most common side effects of Xywav in children include:1

  • Nausea or vomiting
  • Bedwetting
  • Headache
  • Decreased appetite or weight loss
  • Dizziness
  • Sleepwalking

Xywav has a boxed warning, the strictest warning from the FDA. It has this warning because:1

  • It depresses the CNS and may cause breathing problems, fainting, confusion, and death.
  • It has the potential for serious misuse or abuse due to its active ingredients.

These are not all the possible side effects of Xywav. Talk to your doctor about what to expect when taking Xywav. You also should call your doctor if you have any changes that concern you when taking Xywav.

Other things to know

Because of the potential risks of CNS depression and abuse and misuse, Xywav is only available through a restricted program called the Xywav REMS. REMS stands for Risk Evaluation and Mitigation Strategy.1

There are strict safety measures under the REMS program, including:1

  • Doctors who prescribe the drug must be specially certified.
  • The drug is only available through specially certified pharmacies.
  • It is not available from retail pharmacies.
  • The drug is only given to people who are registered in the REMS program and trained in its safe use.

Serious side effects and medical problems can occur if Xywav is taken with any other CNS depressants. These include:1

If you are taking any of these, talk with your doctor before starting Xywav. Signs of serious CNS depression include:1

  • Trouble breathing
  • Severe drowsiness
  • Fainting
  • Low blood pressure

Xywav can make a person severely drowsy. People taking Xywav should not do anything that requires them to be fully awake within 6 hours of taking the drug. This includes driving, operating machinery, or flying an airplane. People should be regularly screened for depression and thoughts of self-harm when taking this drug.1

Talk with your doctor if you notice signs of mood changes. Seek immediate medical attention if you have thoughts of harming yourself or others.

Xywav is not safe to take when pregnant or breastfeeding. Doctors do not know if it is safe for people ages 65 and older. People with liver damage should take lower doses of Xywav.1

Before beginning treatment for narcolepsy, tell your doctor about all your health conditions and any other drugs, vitamins, or supplements you are taking. This includes over-the-counter drugs.

For more information, read the full prescribing information of Xywav.

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