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.
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.
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%).
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.
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Sodium oxybate (SO) is an effective treatment for patients with narcolepsy; however, currently available SO formulations require twice-nightly dosing. The purpose of this study was to evaluate efficacy and safety of FT218, an investigational once-nightly controlled-release SO formulation, for the treatment of excessive daytime sleepiness and cataplexy in patients with narcolepsy types 1 (NT1) and 2 (NT2).
This was a randomized, double-blind, placebo-controlled, multicenter study in patients with narcolepsy ≥16 years old. Patients were randomized 1:1 to receive FT218 or matching placebo: 4.5 g/night for 1 week, 6.0 g/night for 2 weeks, 7.5 g/night for 5 weeks, and 9.0 g/night for 5 weeks (maximum treatment duration, 13 weeks). Coprimary endpoints were mean sleep latency (minutes) on maintenance of wakefulness test (MWT), Clinical Global Impression-Improvement (CGI-I) of sleepiness, and weekly number of cataplexy attacks (NCAs; NT1 only).
A total of 212 patients were randomized and received study treatment (FT218, n=107; placebo, n=105). FT218 showed significant (P<0.001) improvement vs placebo in mean sleep latency on MWT for all evaluated doses; LS mean difference (minutes) between FT218 and placebo was 6.13 at 9.0 g (week 13), 6.21 at 7.5 g (week 8), and 4.98 at 6.0 g (week 3). A higher proportion of patients receiving FT218 were much/very much improved on CGI-I vs placebo (72% vs 31.6% at 9.0 g; 62.6% vs 22.8% at 7.5 g; and 40.1% vs 6.1% at 6.0 g; all P<0.001). LS mean difference between FT218 and placebo in mean weekly NCAs was significant (P<0.001) for all doses: −6.65 at 9.0 g, −6.27 at 7.5 g, and −4.83 at 6.0 g. The most common adverse reactions were nausea, vomiting, headache, dizziness, enuresis, and decreased appetite.
All evaluated doses of FT218 showed significant improvement vs placebo in mean sleep latency on MWT, CGI-I, and weekly NCAs. FT218 was generally well tolerated and the most common adverse events were consistent with known side effects of SO.
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