Lower-Sodium Oxybate is Safe, Effective for Idiopathic Hypersomnia

Phase 3 trial data published in The Lancet Neurology confirm lower-sodium oxybate can safely improve symptoms of idiopathic hypersomnia.

Lower-sodium oxybate became the first The US Food and Drug Administration (FDA) approved treatment for adult idiopathic hypersomnia in August 2021.

Through this phase 3, multicenter, placebo-controlled, double-blind, randomized withdrawal study on patients aged 18-75 with idiopathic hypersomnia, researchers aimed to assess the efficacy and safety of lower-sodium oxybate as a treatment for idiopathic hypersomnia in adults.

A total of 154 participants enrolled between November 27, 2018 and March 6, 2020 received lower-sodium oxybate once or twice nightly for an open label titration and optimization period, which was followed by a 2-week open-label, stable-dose period. Following this, 115 participants were randomized 1:1 to receive lower-sodium oxybate or placebo.

Change in the Epworth Sleepiness Scale (ESS) was the primary endpoint for efficacy while researchers used the safety population to assess adverse events.

“To maintain masking of treatment assignment, placebo and lower-sodium oxybate oral solutions were matched in volume, appearance, and taste. During the double-blind, randomised withdrawal period, participants and investigators were unaware of treatment assignments,” wrote Yves Dauvilliers, MD, Sleep and Wake Disorders Centre, Department of Neurology, Gui de Chauliac Hospital, Montpellier, France, and co-researchers.

Participants receiving placebo(n=59) had increasing (or worsening) ESS scores during the double-blind, randomized withdrawal period. For patients receiving lower-sodium oxybate(n=56), ESS scores remained stable.

Nausea (22%), headache(18%), dizziness(12%), anxiety(11%) and vomiting(11%) were the most common treatment-emergent adverse events.

“Lower-sodium oxybate treatment resulted in a clinically meaningful improvement in idiopathic hypersomnia symptoms, with an overall safety profile consistent with that reported for narcolepsy,” concluded Dr Dauvilliers et al.

Reference

Dauvilliers Y, Arnulf I, Foldvary-Schaefer N, et al. Safety and efficacy of lower-sodium oxybate in adults with idiopathic hypersomnia: a phase 3, placebo-controlled, double-blind, randomised withdrawal study. Lancet Neurol. 2022;21(1):53-65. doi:10.1016/S1474-4422(21)00368-9