calcium, magnesium, potassium, and sodium oxybates

General information

• Class: Adjunctive therapy
• Common US brands: Xywav
• Typical dose range: Narcolepsy (adults): start 4.5 g per night in two doses (2.25 g at bedtime and 2.25 g 2.5–4 hours later). Titrate by 1.5 g per night at weekly intervals to an effective range of 6–9 g per night; doses above 9 g per night or single doses above 6 g are not recommended (label).
• Therapeutic drug monitoring not routinely recommended.
• Last reviewed: 2026-02-22

Dosing & forms

• Forms/strengths: Oral solution: 0.5 g/mL total salts (equivalent to 0.413 g/mL of oxybate) (label).
• Frequency: Narcolepsy (adults): start 4.5 g per night in two doses (2.25 g at bedtime and 2.25 g 2.5–4 hours later). Titrate by 1.5 g per night at weekly intervals to an effective range of 6–9 g per night; doses above 9 g per night or single doses above 6 g are not recommended (label).
• Typical range: Narcolepsy (adults): start 4.5 g per night in two doses (2.25 g at bedtime and 2.25 g 2.5–4 hours later). Titrate by 1.5 g per night at weekly intervals to an effective range of 6–9 g per night; doses above 9 g per night or single doses above 6 g are not recommended (label).

Mechanism (brief)

Nighttime CNS depressant (oxybate/GHB; lower-sodium oxybate salts) indicated for cataplexy or excessive daytime sleepiness in narcolepsy (patients 7+), and for idiopathic hypersomnia in adults; Schedule III with boxed warning for respiratory depression and abuse/misuse and dispensed under a REMS (label).

Metabolism & Half‑life

• Metabolism: Non-CYP metabolism (GHB metabolic pathways) (label).
• Half‑life: Single-dose mean 0.66 h

Therapeutic Drug Monitoring (TDM)

Recommended: No

Monitoring highlights

• Respiratory risk and CNS depressant co-medication review (label/clinical).
• Safe storage and misuse/diversion monitoring consistent with REMS (label/clinical).
• Nighttime fall risk assessment and environment planning (clinical).
• Mood and neuropsychiatric symptom monitoring (label/clinical).
• Hepatic impairment assessment for dosing and safety (label).
• Review of interaction with divalproex/valproate if co-prescribed and confirm dose reduction (label/clinical).

Sources

• XYWAV (calcium, magnesium, potassium, and sodium oxybates) oral solution prescribing information — DailyMed (2025)
• Treatment of central disorders of hypersomnolence: an American Academy of Sleep Medicine clinical practice guideline — Journal of Clinical Sleep Medicine (2021)
• Treatment of central disorders of hypersomnolence: an American Academy of Sleep Medicine systematic review, meta-analysis, and GRADE assessment — Journal of Clinical Sleep Medicine (2021)
• Efficacy and safety of calcium, magnesium, potassium, and sodium oxybates (lower-sodium oxybate [LXB]; JZP-258) in a placebo-controlled, double-blind, randomized withdrawal study in adults with narcolepsy with cataplexy — Sleep (2020)
• Calcium, Magnesium, Potassium, and Sodium Oxybates Oral Solution: A Lower-Sodium Alternative for Cataplexy or Excessive Daytime Sleepiness Associated with Narcolepsy — Nature and Science of Sleep (2022)