Sodium oxybate

Mechanism of action

Sodium oxybate is gamma-hydroxybutyrate (GHB), a natural metabolite of GABA. How it helps narcolepsy is not known; its effects are thought to come through GABA-B receptors during the night, with less cataplexy and less daytime sleepiness as a result.

1. Taken at bedtime; GHB acts on GABA-B receptors
2. A second dose follows later in the night
3. Fewer cataplexy attacks and less daytime sleepiness

Indications

• Cataplexy and excessive daytime sleepiness in narcolepsy Narcolepsy →

Adverse effects

Common

• Nausea and vomiting
• Dizziness and somnolence
• Bed-wetting
• Tremor

Contraindications

• Alcohol or sedative hypnotics
• Succinic semialdehyde dehydrogenase deficiency

Key interactions

Alcohol, sedative hypnotics, opioids and other CNS depressants

Deep sedation and respiratory depression

Divalproex (valproate)

Higher GHB exposure; the starting dose is reduced

What is monitored

• Breathing during sleep, especially with sleep apnoea or lung disease
• Mood, suicidal thoughts and night-time behaviour
• Sodium intake in heart failure, hypertension or kidney disease

Administration and safety

• Dispensed only through a restricted (REMS) programme in the United States
• The solution is diluted and prepared before bedtime; two doses are taken in bed during the night
• First dose well after the last meal, because food lowers its effect
• Controlled medicine (Schedule III); illicit GHB is a drug of abuse

Pregnancy and breastfeeding

Human data are inadequate; it passes into breast milk.

Nursing care

• Ask about alcohol, sedatives, sleep apnoea and depression before starting
• Teach to take each dose in bed and lie down right away
• Teach to avoid driving and hazardous tasks for several hours after a dose
• Store it locked away from others

Pharmacokinetics

Absorption

Rapid, about 88% bioavailable; food delays it and lowers peak levels

Metabolism

Mainly to carbon dioxide and water through the Krebs cycle

Half-life

Short, about half an hour to one hour

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Connections

← Back to the class: Wake-promoting agents and narcolepsy drugs

Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.

Sources: DailyMed - SODIUM OXYBATE solution (DailyMed (U.S. National Library of Medicine), 2026); ATCDDD - ATC/DDD Index (WHO Collaborating Centre for Drug Statistics Methodology, 2026).

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Representative model, for educational purposes only.