Efficacy of Lower-Sodium Oxybate in Participants With Idiopathic Hypersomnia: Results From the Open-label Treatment Phase of a Clinical Study

Abstract: Introduction: Idiopathic hypersomnia is characterized by excessive daytime sleepiness, sleep inertia, and in some patients, long sleep time; these symptoms may partially overlap with psychiatric disorders. This post hoc analysis evaluated efficacy of lower-sodium oxybate (LXB; Xywav®) in participants with idiopathic hypersomnia either taking alerting agents or treatment naive at study entry. Methods: Adults (aged 18–75 years) with idiopathic hypersomnia took LXB treatment in the open-label titration and optimization period (OLT; 10–14 weeks) and 2-week, open-label, stable-dose period (SDP) of a phase 3 clinical trial (NCT03533114). Epworth Sleepiness Scale (ESS), Idiopathic Hypersomnia Severity Scale (IHSS), and Patient Global Impression of Change (PGIc) were assessed at baseline and weeks 1, 4, and 8 of the OLT, end of OLT, and end of SDP. Results: The modified intent-to-treat population included 109 participants (n=62 taking alerting agents; n=47 treatment naive). At baseline, mean (SD) ESS scores were similar between groups (alerting agents, 16.1 [3.0]; treatment naive, 16.6 [2.6]), as were IHSS scores (alerting agents, 32.6 [7.2]; treatment naive, 32.3 [7.8]). Clinical improvement was seen in both groups. At the end of open-label treatment, mean (SD) ESS scores were 6.5 (4.2) and 5.7 (3.8) in participants taking alerting agents and treatment-naive participants, respectively; mean IHSS scores were 15.8 (8.6) and 14.8 (8.3), respectively. Most participants reported improvement (alerting agents, 100%; treatment naive, 97.9%) on the PGIc at end of open-label treatment. Conclusions: Most participants with idiopathic hypersomnia demonstrated improvement of symptoms with LXB regardless of whether other concurrent treatments were present.Short Description: The efficacy of lower-sodium oxybate during open-label titration and optimization and stable dosing was assessed in participants with idiopathic hypersomnia during a phase 3 clinical trial. Participants were grouped by treatment at study entry (taking alerting agents or treatment naive). Epworth Sleepiness Scale and Idiopathic Hypersomnia Severity Scale scores improved similarly across groups. Most participants in both groups reported improvement on the Patient Global Impression of Change.Name of Sponsoring Organization(s): Jazz Pharmaceuticals