Abstract
Introduction
Idiopathic hypersomnia (IH) is a rare central hypersomnolence disorder. In a randomized, controlled study of lower-sodium oxybate (LXB; Xywav™) in adults with IH (NCT03533114), significant differences for LXB compared with placebo were observed in Epworth Sleepiness Scale (ESS; primary efficacy endpoint), self-reported Patient Global Impression of Change (PGIc), and IH Severity Scale (IHSS; key secondary endpoints). In this clinical study, investigators were permitted to initiate LXB dosing on a once-nightly or twice-nightly regimen.
Methods
Eligible participants aged 18–75 years began LXB treatment, administered once or twice nightly during an open-label treatment/titration and optimization period (OLTTOP; 10–14 weeks); dose amount/regimen could be adjusted during this period. Participants next entered a 2-week, open-label, stable-dose period (SDP), then were randomized to placebo or to continue LXB treatment during a 2-week, double-blind, randomized withdrawal period (DBRWP). P values are nominal for this exploratory analysis.
Results
Of 154 enrolled participants, 40 (26%) initiated LXB treatment on a once-nightly regimen. In the efficacy population (n=115), 27 participants were on a once-nightly regimen during SDP (48.1% of whom initiated treatment once nightly during OLTTOP) and 88 participants were on a twice-nightly regimen during SDP (86.4% of whom initiated treatment twice nightly during OLTTOP). During SDP, median (min, max) LXB total dose was 4.5 (2.5, 6) g/night (once-nightly group) and 7.5 (4.5, 9) g/night (twice-nightly group). ESS scores worsened in participants randomized to placebo vs those continuing LXB in the once-nightly group (n=11 and n=15, respectively; LS mean difference [95% CI]: −4.93 [−7.41, −2.46]; P=0.0004) and twice-nightly group (n=47 and n=41, respectively; LS mean difference [95% CI]: −7.44 [−9.15, −5.72]; P<0.0001). Worsening was also observed in PGIc (once-nightly: 81.8% [placebo] vs 26.7% [LXB]; P=0.0077; twice-nightly: 89.4% [placebo] vs 19.5% [LXB]; P<0.0001) and IHSS score (estimated median difference [95% CI], once-nightly: −9.00 [−16.0, −3.0]; P=0.0028; twice-nightly: −12.00 [−15.0, −8.0]; P<0.0001). Common adverse events included nausea (21.4%), headache (16.2%), anxiety (14.9%), dizziness (11.7%), insomnia (11.7%), and vomiting (10.4%).
Conclusion
The efficacy and safety of LXB in IH were demonstrated for both once-nightly and twice-nightly regimens. The majority of participants initiated and remained on a twice-nightly regimen.
Support (if any)
Jazz Pharmaceuticals
Cerebrospinal fluid monoamine levels in central hypersomnolence disorders
