Sodium oxybate
This page is a reference summary of published evidence and regulatory documents. It is not a substitute for individual medical advice, and it is not a recommendation to take or avoid any medicine.
Medically reviewed by Dr. Sofia Lindqvist, · Last reviewed 11 August 2026
Sodium oxybate, sold as Xyrem, is a central nervous system depressant taken at night rather than a wakefulness agent taken in the morning. It occupies an unusual position in narcolepsy treatment, and it is here because it is one of the FDA-approved treatments for the condition.
On this page
How it differs from everything else here
Night
when it is taken
2
doses per night, original form
C-III
US control status
Restricted
distribution programme
Every other drug on this site promotes wakefulness during the day. Sodium oxybate improves the quality of sleep at night, and daytime alertness improves as a downstream consequence.
Dose at bedtime
and again 2.5–4 h later
Deeper, consolidated sleep
Less cataplexy
Better daytime alertness
The indirect route: the drug acts overnight, and the daytime benefit is a second-order effect.
The two-dose schedule is not a detail. It requires waking in the night to take the second dose, which is the practical objection patients raise most often.
Approved uses
Sodium oxybate is approved for cataplexy and excessive daytime sleepiness in narcolepsy. Historically it has been the primary FDA-approved treatment for cataplexy specifically — the sudden loss of muscle tone that modafinil and solriamfetol do not touch.
Formulations
Several formulations exist, and the differences between them are mostly about sodium load and dosing burden.
| Product | What it is | Why it exists |
|---|---|---|
| Xyrem | Original sodium oxybate | The reference product |
| Xywav | Lower-sodium mixed salts: calcium, magnesium, potassium and sodium oxybates | Developed to reduce the daily sodium load |
| Lumryz | Once-nightly extended-release oxybate | Removes the middle-of-the-night second dose |
Restricted distribution
Not a standard pharmacy medicine
Because of its abuse potential and its profile as a central nervous system depressant, sodium oxybate is available only through a restricted distribution programme with certified prescribers and pharmacies. It cannot be filled at a retail pharmacy.
Product labelling also discourages getting out of bed after any oxybate dose, because of the depth of sedation.
Why it is on this site
Sodium oxybate is rarely what someone researching modafinil is looking for. It is included because a reference on narcolepsy pharmacology that omits the primary cataplexy treatment is incomplete, and because patients with narcolepsy type 1 often end up on a combination that includes it.
Why is sodium oxybate taken twice in one night?
Its effect is short. The original formulations are dosed at bedtime and again two and a half to four hours later, which means setting an alarm. The once-nightly extended-release formulation was developed to remove that second dose.
Is it a wakefulness drug?
No. It is a central nervous system depressant taken at night. Daytime alertness improves as a consequence of better-consolidated sleep, not because the drug is stimulating.
Can it be filled at a normal pharmacy?
No. It is available only through a restricted distribution programme with certified prescribers and a certified pharmacy.