Treatment with lower-sodium oxybate (LXB) improved daytime sleepiness among patients with idiopathic hypersomnia (IH) according to results of a phase 3, placebo-controlled, double-blind, randomized clinical trial, to be presented during the American Academy of Neurology 2021 Virtual Annual Meeting, to be held April 17 to 22, 2021.

Patients (N=154) with IH were recruited for this study. They were given LXB Xywav, which has 92% less sodium than Xyrem, for a 10-14 week open-label titration and optimization stage. Following titration, patients were randomly assigned to continue on LXB or receive a placebo for 2 weeks. Study researchers assessed patients by Epworth Sleepiness Scale (ESS), Patient Global Impression of Change, and IH Severity Scale.

Patients has a mean age of 40 (standard deviation [SD], ±14) years, 68% were women, and average baseline ESS score was 16 (SD, ±3.6 points). After the titration period, the average dose of LXB was optimized as 6.0±1.6 grams/night.

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Following the titration period, significant worsening of ESS scores were observed among patients randomly assigned to switch to a placebo (least squares mean difference, -6.51; 95% CI, -7.99 to -5.03; P <.0001). Similarly, IH Severity Scale scores were poorer among the placebo recipients (estimated median difference, -12.00; 95% CI, -15.0 to -8.0; P <.0001). Patient Global Impression of Change was 88.1% among the placebo cohort and 21.4% for the treatment group (P <.0001).

The common adverse events of nausea (21.4%), headache (16.2%), dizziness (11.7%), vomiting (10.4%), and anxiety (10.4%) were reported by fewer than a quarter of study participants. Study researchers observed a total of 4 serious adverse events (syncope, rhabdomyolysis, nephrolithiasis/pyelonephritis, and non-cardiac chest pain), but determined these were not associated with the LXB treatment.

This study may have been limited by its short double-blind treatment duration.

The study authors concluded LXB significantly improved excessive daytime sleepiness, overall IH symptoms, and self-reported global change among patients with IH. Xywav therapy was associated with little risk for adverse effects.

Disclosure: Multiple authors declared affiliations with industry. Please refer to the original article for a full list of disclosures.


Dauvilliers Y, Arnulf I, Foldvary-Schaefer N, et al. Efficacy and safety of lower-sodium oxybate in a phase 3, placebo-controlled, double-blind, randomized withdrawal study in adult participants with idiopathic hypersomnia. Presented at: American Academy of Neurology 2021 Virtual Annual Meeting; April 17-22, 2021.

This article originally appeared on Neurology Advisor