Mixed-salt oxybates

XYWAV

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Mixed-salt oxybates ballicule: receptor binding, kinetics and half-life diagram — Mechanism of action: Mixed-salt oxybates ballicule

Mixed-salt oxybates XYWAV mascot mnemonic cartoon — Visual mnemonic: Mixed-salt oxybates mascot

What it isMixed-salt GHB and GABA-B agonist (XYWAV, 2020); narcolepsy with cataplexy or sleepiness, and idiopathic hypersomnia.

Why this oneIt contains ~92% less sodium than Xyrem and is the only drug approved for idiopathic hypersomnia (2021).

What limits itProfound CNS and respiratory depression makes alcohol, sedatives, and unsupervised access dangerous; dispensing is restricted.

Mixed-salt oxybates molecular structure (skeletal formula) — Molecular structure: Mixed-salt oxybates

FDA-approved for

narcolepsy (cataplexy/EDS) (2020)
idiopathic hypersomnia (2021)

FDA label

Read the full label on DailyMed ↗

BOXED WARNING CNS depression; abuse and misuse (XYWAV and XYREM REMS)

FDA dosing	Population	Start	Target	Max
Cataplexy or excessive daytime sleepiness in narcolepsy	Adults	4.5 g/night divided into two nightly doses	6–9 g/night	9 g/night
Cataplexy or excessive daytime sleepiness in narcolepsy	Pediatric 7+ y	Weight-based, divided into two nightly doses		Weight-based (≥45 kg: 9 g/night)
Idiopathic hypersomnia	Adults	≤4.5 g/night divided (twice nightly) or ≤3 g (once nightly)		9 g/night (twice nightly) / 6 g (once nightly)

Titration Increase by ≤1.5 g/night per week

Renal Undefined

Hepatic Reduce starting dose by one-half

Doses >9 g/night or single doses >6 g have not been studied

Instructions

Take at least 2 h after eating
Dilute each dose with ~1/4 cup (60 mL) water; take in bed and lie down immediately
First dose at bedtime, second dose 2.5–4 h later
Prepared doses must be consumed within 24 h

Available strengths

sol 0.5 g/mL (oxybate equivalents)

Contraindications

In combination with sedative hypnotics
In combination with alcohol
Patients with succinic semialdehyde dehydrogenase deficiency

Cautions

CNS/respiratory depression
Depression and suicidality
Confusion, anxiety, and other psychiatric reactions
Parasomnias (sleepwalking)
Sleep-disordered breathing

Adverse reactions

Nausea
Headache
Dizziness
Anxiety
Insomnia
Decreased appetite
Hyperhidrosis
Vomiting
Diarrhea
Dry mouth
Parasomnia
Somnolence
Enuresis (pediatric)

Pregnancy No adequate human data; animal data suggest possible fetal harm

Lactation GHB excreted in human milk; insufficient data on breastfed infant

Cost

Mixed-salt oxybates (XYWAV)

Strength		#/mo	generic $/unit	CostPlus
0.5 g/mL	sol	per unit		not offered

NADAC is a voluntary CMS survey of what retail community pharmacies pay for the drugs they stock. Mixed-salt oxybates is dispensed outside retail pharmacies, so it rarely appears on surveyed invoices.

⚠ BOXED WARNINGS

CNS depression
Abuse and misuse

Classes and tags

Clinical profile

Therapeutic safety burden4 / 4

Overdose danger4 / 4

Weight-gain liability0 / 4

Sedation liability3 / 4

QT / Torsades0 / 4

Direct muscarinic antagonism0 / 4

Embryofetal risk2 / 4

Legacy pregnancy categoryC

Defining liabilityPotentially fatal respiratory depression and misuse risk

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Memory aids: interaction avatars

no kinetic interactions

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