Improvement in Sleep Latency With Extended-Release Once-Nightly Sodium Oxybate for the Treatment of Adults With Narcolepsy: Analysis From the Phase 3 REST-ON Clinical Trial

Background In the REST-ON clinical trial (NCT02720744), mean sleep latency on the Maintenance of Wakefulness Test (MWT) was significantly improved with extended-release once-nightly sodium oxybate (ON-SXB) vs placebo (P<0.001) in participants with narcolepsy. This post hoc analysis assessed response to treatment and improvement in excessive daytime sleepiness. Methods Participants with narcolepsy aged ≥16 years were randomized 1:1 to receive ON-SXB (4.5 g, week 1; 6 g, weeks 2–3; 7.5 g, weeks 3–8; and 9 g, weeks 9–13) or placebo. Mean sleep latency on the MWT was measured across 5 trials of ≤30 minutes each. Post hoc assessments included percentage of participants whose sleep latency improved ≥5, ≥10, ≥15, and ≥20 minutes and with a mean sleep latency of 30 minutes. Results Significantly more participants receiving ON-SXB vs placebo experienced increased mean sleep latency ≥5 minutes (all doses P<0.001), ≥10 minutes (all doses P<0.001), ≥15 minutes (6 and 7.5 g, P<0.001; 9 g, P<0.01), and ≥20 minutes (6 g, P<0.01; 7.5 g, P<0.001; 9 g, P<0.05). More participants receiving ON-SXB had mean sleep latency of 30 minutes vs placebo (6 g, 5.7% vs 0%, respectively [P<0.05]; 7.5 g, 10.5% vs 1.3% [P<0.05]; 9 g, 13.2% vs 5.1% [P=0.143]). Conclusions Significantly more participants who received ON-SXB experienced increased mean sleep latency ≥5 to ≥20 minutes; at the 2 highest doses, >10% remained awake for the entirety of the MWT. ON-SXB offers a once-at-bedtime treatment option for adults with narcolepsy.