Sodium oxybate (Xyrem®): A new and effective treatment for narcolepsy with cataplexy

Abstract

Sodium oxybate (SXB; Xyrem®) is the sodium salt of gamma hydroxybutyric acid (GHB). SXB has been approved in the United States for the treatment of cataplexy and excessive daytime sleepiness (EDS) in patients with narcolepsy and in the European Union for the treatment of narcolepsy with cataplexy. Randomized clinical trials have shown that SXB is highly effective in reducing the frequency of cataplexy and in reducing EDS in patients with narcolepsy. In addition, SXB improved sleep architecture by increasing delta power and the duration of slow-wave sleep and by reducing nocturnal awakenings in patients with narcolepsy with cataplexy. Global function and health-related quality of life were also improved by SXB. The majority of the above effects are dose-related. SXB is administered orally after mixing with water. It is rapidly absorbed and eliminated with a mean elimination half-life of 30-60 min, and its duration of action is 2-4 h. Therefore, SXB must be administered twice during the night to consolidate 6-8 h of nocturnal sleep. In general, SXB is well tolerated, and the most commonly reported adverse events are nausea, vomiting, dizziness, and urinary incontinence. SXB is a drug with potential for misuse and abuse. In addition, SXB has a narrow safety margin with a risk of toxicity. Therefore, strict riskmanagement strategies and rigorous adherence to the titration schedule are essential.