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Low-sodium oxybate (LXB) treatment improved daytime sleepiness in patients with idiopathic hypersomnia (IH), according to results from a placebo-controlled, double-blind, randomized phase 3 clinical trial presented during the American Academy of Neurology 2021 Annual Virtual Meeting, Nov. until April 22, 2021.
Patients (N = 154) with IH were recruited for this study. They received LXB Xywav, which contains 92% less sodium than Xyrem, for a 10-14 week open titration and optimization phase. After titration, patients were randomly assigned to continue LXB or to receive placebo for 2 weeks. The study researchers rated patients using the Epworth Sleepiness Scale (ESS), the patient’s global impression of change, and the IH severity scale.
The patient has an average age of 40 years (standard deviation) [SD], ± 14) years, 68% were women, and the mean baseline ESS was 16 (SD, ± 3.6 points). After the titration period, the average LXB dose was optimized to 6.0 ± 1.6 g / night.
After the titration period, patients who were randomly switched to placebo had a significant deterioration in ESS scores (mean least squares difference: -6.51; 95% CI: -7.99 to -5.03 ; P <0.0001). Similarly, the IH severity scale scores were worse among placebo recipients (estimated mean difference: -12.00; 95% CI: -15.0 to -8.0; P <0.0001). The global impression of change in the patient was 88.1% in the placebo cohort and 21.4% in the treatment group (P <0.0001).
The most common adverse events of nausea (21.4%), headache (16.2%), dizziness (11.7%), vomiting (10.4%) and anxiety (10.4%) were less than a quarter the study participant reports. The study researchers observed a total of 4 serious adverse events (syncope, rhabdomyolysis, nephrolithiasis / pyelonephritis, and non-cardiac chest pain) but found that these were not associated with LXB treatment.
This study may have been limited by the short duration of the double-blind treatment.
The study’s authors concluded that LXB significantly improved excessive daytime sleepiness, general IH symptoms, and self-reported global changes in patients with IH. Xywav therapy was associated with a low risk of side effects.
Disclosure: Several authors have declared their affiliations with the industry. For a full list of details, see the original article.
Dauvilliers Y., Arnulf I., Foldvary-Schaefer N. et al. Efficacy and Safety of Low 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 Annual Virtual Meeting; 17.-22. April 2021.